MAX4554, MAX4555, MAX4556

MAX4554, MAX4555, MAX4556

19-1358; Rev 0; 4/98

Force-Sense Switches

General Description

The MAX4554/MAX4555/MAX4556 are CMOS analog ICs configured as force-sense switches for Kelvin sensing in automated test equipment (ATE). Each part contains high-current, low-resistance switches for forcing current, and higher resistance switches for sensing a voltage or switching guard signals. The MAX4554 contains two force switches, two sense switches, and two guard switches configured as two triple-pole/single-throw

(3PST) normally open (NO) switches. The MAX4555 contains four independent single-pole/single-throw (SPST) normally closed (NC) switches, two force switches, and two sense switches. The MAX4556 contains three independent single-pole/double-throw (SPDT) switches, of which one is a force switch and two are sense switches.

These devices operate from a single supply of +9V to

+40V or dual supplies of ±4.5V to ±20V. On-resistance

(6

Ω max) is matched between switches to 1

Ω max.

Each switch can handle Rail-to-Rail

® analog signals.

The off-leakage current is only 0.25nA at +25°C and

2.5nA at +85°C. The MAX4554 is also fully specified for

+20V and -10V operation.

All digital inputs have +0.8V and +2.4V logic thresholds, ensuring both TTL- and CMOS-logic compatibility.

Automated Test Equipment (ATE)

Applications

Calibrators

Precision Power Supplies

Automatic Calibration Circuits

Asymmetric Digital Subscriber Line (ADSL) with Loopback

Features

6

Force Signal Paths (±15V Supplies)

1

Force Signal Matching (±15V Supplies)

60

Sense-Guard Signal Paths (±15V Supplies)

8

Sense-Guard Signal Matching (±15V Supplies)

Rail-to-Rail Signal Handling

Break-Before-Make Switching (MAX4556)

t

ON and t

OFF

= 275ns (±15V Supplies)

Low 1µA Power Consumption

>2kV ESD Protection per Method 3015.7

TTL/CMOS-Compatible Inputs

Ordering Information

PART

MAX4554

CPE

MAX4554CSE

MAX4554C/D

MAX4554EPE

MAX4554ESE

TEMP. RANGE

0°C to +70°C

0°C to +70°C

0°C to +70°C

-40°C to +85°C

-40°C to +85°C

PIN-PACKAGE

16 Plastic DIP

16 Narrow SO

Dice*

16 Plastic DIP

16 Narrow SO

Ordering Information continued at end of data sheet.

* Contact factory for availability.

Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.

Pin Configurations/Functional Diagrams/Truth Tables

TOP VIEW

MAX4554

NOG1 1

NOS1 2

NOF1* 3

V4

GND 5

NOF2* 6

NOS2 7

NOG2 8

16 COMG

15 COMS

14 COMF*

13 V+

12 VL

11 IN1

10 IN2

9 EN

MAX4554

EN

IN1 IN2

COMG COMS COMF*

1 X X OFF OFF OFF

0

0

0

0

0

0

1

1

0

1

0

1

OFF

NOG2

NOG1

NOG1

&

NOG2

OFF

NOS2

NOS1

NOS1

&

NOS2

OFF

NOF2*

NOF1*

NOF1*

&

NOF2*

NOTE: SWITCH POSITIONS SHOWN WITH IN_ = LOW

*INDICATES HIGH-CURRENT, LOW-RESISTANCE FORCE SWITCH

X = DON’T CARE

MAX4555/MAX4556 shown at end of data sheet.

DIP/SO

________________________________________________________________

Maxim Integrated Products

1

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.

Force-Sense Switches

ABSOLUTE MAXIMUM RATINGS

(Voltages referenced to GND)

V+ ...........................................................................-0.3V to +44V

V- ............................................................................-25V to +0.3V

V+ to V-...................................................................-0.3V to +44V

All Other Pins (Note 1) ..........................(V- - 0.3V) to (V+ + 0.3V)

Continuous Current into Force Terminals .......................±100mA

Continuous Current into Any Other Terminal....................±30mA

Peak Current into Force Terminals

(pulsed at 1ms, 10% duty cycle).................................±300mA

Peak Current into Any Other Terminal

(pulsed at 1ms, 10% duty cycle).................................±100mA

ESD per Method 3015.7 ..................................................>2000V

Continuous Power Dissipation (T

A

= +70°C)

Plastic DIP (derate 10.53mW/°C above +70°C) ...........842mW

Narrow SO (derate 8.7mW/°C above +70°C) ...............696mW

Operating Temperature Ranges

MAX455_C_ E ......................................................0°C to +70°C

MAX455_E_ E ...................................................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10sec) .............................+300°C

Note 1:

Signals on analog or digital pins exceeding V+ or V- are clamped by internal diodes. Limit forward diode current to maximum current rating.

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

ELECTRICAL CHARACTERISTICS—MAX4554 (+20V, -10V Supplies)

(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS PARAMETER SYMBOL

6

ANALOG SWITCH (FORCE)

Analog Signal Range

V

COMF

,

V

NOF_

(Note 3) C, E VV+ V

On-Resistance R

ON

V

COMF

= 10V, I

COMF

= 10mA

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NOF_ Off-Leakage Current

R

ON

R

FLAT(ON)

I

NOF_(OFF)

V

COMF

= 10V, I

COMF

= 10mA

V

COMF

= +5V, 0V, -5V;

I

COMF

= 10mA

V+ = 22V, V- = -11V,

±

V

COMF

= ±10V, V

NOF_

= 10V

COMF Off-Leakage Current I

COMF(OFF)

V+ = 22V, V- = -11V,

V

COMF

= ±10V, V

NOF_

±

COMF On-Leakage Current I

COMF(ON)

V+ = 22V, V- = -11V,

V

COMF

= ±10V

Charge Injection Q

60

ANALOG SWITCH (SENSE-GUARD)

V

COMF

= 0, Figure 13

Analog Signal Range

V

COMS

,

V

COMG

,

V

NOS_

,

V

NOG_

(Note 3)

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

C, E

-0.25

-2.5

-0.5

-2.5

-0.5

-10

V-

3.5

0.4

0.5

0.03

0.03

0.06

80

2.5

0.5

2.5

0.5

10

6

7

1

1.5

1.5

2.0

0.25

V+

Ω nA nA nA pC

V

On-Resistance

On-Resistance Match

(Note 4)

R

ON

R

ON

V

COM_

= 10V, I

COM_

= 1mA

V

COM_

= 10V, I

COM_

= 1mA

+25°C

C, E

+25°C

C, E

34

5

60

70

8

10

2 _______________________________________________________________________________________

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4554 (+20V, -10V Supplies) (continued)

(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

On-Resistance Flatness

(Note 5)

NOS_, NOG_ Off-Leakage

Current

COMS, COMG Off-Leakage

Current

COMS, COMG On-Leakage

Current

Charge Injection

LOGIC INPUT

IN_, EN Input Logic

Threshold High

IN_, EN Input Logic

Threshold Low

IN_,

EN Input Current Logic

High or Low

R

FLAT(ON)

I

NOS_(OFF)

,

I

NOG_(OFF)

I

COMS(OFF)

,

I

COMG(OFF)

I

COMS(ON)

,

I

COMG(ON)

Q

V

IN_H

,

V

ENH

V

IN_L

,

V

ENL

I

IN_H

, I

IN_L

,

I

ENH

, I

ENL

V

COM_

= +5V, 0V, -5V;

I

COM_

= 10mA

V+ = 22V; V- = -11V; V

COM_

= ±10V;

V

NOS_,

V

NOG_

= ±10V

V+ = 22V; V- = -11V; V

COM_

= ±10V;

V

NOS_,

V

NOG_

= ±10V

V+ = 22V, V- = -11V, V

COM_

= ±10V

V

COM_

= 0, Figure 13

V

IN_

= V

EN

= 0 or VL

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

C, E

-0.25

-2.5

-0.25

-2.5

-0.5

-5.0

0.8

-0.5

3.5

0.02

0.02

0.04

6

1.6

1.6

0.03

9

10

0.25

2.5

0.25

2.5

0.5

5.0

2.4

0.5

Ω nA nA nA pC

V

V

µA

Turn-On Time (Force)

Turn-On Time

(Sense-Guard)

Turn-Off Time (Force)

Turn-Off Time

(Sense-Guard)

Enable Time On

Enable Time Off

NOF_ Off-Capacitance

NOS_, NOG_

Off-Capacitance

COMF Off-Capacitance

COMS, COMG

Off-Capacitance

COMF On-Capacitance

COMS, COMG

On-Capacitance

Total Harmonic Distortion

(Force)

Off Isolation (Force) t

ON t

ON t

OFF t

OFF t

EN t

EN

C

OFF

C

OFF

C

OFF

C

OFF

C

ON

C

ON

THD

V

ISO

V

COMF

= 3V, R

L

= 300

,

Figure 10

V

COMS,

V

COMG

= 10V; R

L

= 1k

;

Figure 10

V

COMF

= 3V, R

L

= 300

,

Figure 10

V

COMS,

V

COMG

= 10V; R

L

= 1k

;

Figure 10

V

COM_

= 10V, Figure 11

V

COM_

= 10V, Figure 11

V

NOF

= GND, f = 1MHz, Figure 14

V

NOS_,

V

NOG_

= GND; f = 1MHz;

Figure 14

V

COMF

= GND, f = 1MHz, Figure 14

V

COMS,

V

COMG

= GND; f = 1MHz;

Figure 14

V

COMF

= GND, f = 1MHz, Figure 14

V

COMS,

V

COMG

= GND; f = 1MHz;

Figure 14

R

IN_

= 50

, R

OUT

= 50

, f = 1MHz,

V

COM_

= 100mV

RMS

, Figure 15

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

+25°C

+25°C

+25°C

+25°C

+25°C

+25°C

+25°C

150

150

130

130

375

170

22

7

50

15

130

30

0.007

-30

300

350

300

350

300

350

300

350

500

600

275

350 ns ns ns ns ns pF pF pF pF ns pF pF

% dB

_______________________________________________________________________________________ 3

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4554 (+20V, -10V Supplies) (continued)

(V+ = +20V, V- = -10V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

POWER SUPPLY

Power-Supply Range V+, VL, VV

V+ Supply Current

V- Supply Current

VL Supply Current

Ground Current

I+

I-

I

L+

I

GND

VL

4.5V

V+ = 22V; V- = -11V;

V

EN,

V

IN_

= 0 or VL

V+ = 22V; V- = -11V;

V

EN,

V

IN_

= 0 or VL

V+ = 22V; V- = -11V;

V

EN,

V

IN_

= 0 or VL

V+ = 22V; V- = -11V;

V

EN,

V

IN_

= 0 or VL

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

±4.5

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

±20

1.0

5.0

1.0

5.0

1.0

5.0

1.0

5.0

µA

µA

µA

µA

ELECTRICAL CHARACTERISTICS—MAX4554 (±15V Supplies)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

6

ANALOG SWITCH (FORCE)

Analog Signal Range

V

COMF

,

V

NOF_

(Note 3) C, E VV+ V

On-Resistance R

ON

V

COMF

= ±10V, I

COMF

= 10mA

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NOF_ Off-Leakage Current

COMF Off-Leakage Current

R

ON

R

FLAT(ON)

I

NOF_(OFF)

I

COMF(OFF)

V

COMF

= ±10V, I

COMF

= 10mA

V

COMF

= +5V, 0V, -5V;

I

COMF

= 10mA

V+ = 16.5V, V- = -16.5V,

±

V

COMF

= ±10V, V

NOF_

= 10V

V+ = 16.5V, V- = -16.5V,

V

COMF

= ±10V, V

NOF_

±

COMF On-Leakage Current I

COMF(ON)

Charge Injection Q

60

ANALOG SWITCH (SENSE-GUARD)

V+ = 16.5V, V- = -16.5V,

V

COMF

= ±10V

V

COMF

= 0, Figure 13

Analog Signal Range

V

COMS

,

V

COMG

,

V

NOS_

,

V

NOG_

(Note 3)

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

-0.25

-2.5

-0.5

-5.0

-0.5

-10

V-

4

0.5

0.1

0.03

0.03

0.06

100

1.5

0.25

2.5

0.5

5.0

0.5

10

6

7

1

1.5

1

V+

Ω nA nA nA pC

V

On-Resistance R

ON

V

COM_

= ±10V, I

COM_

= 1mA

+25°C

C, E

38 60

70

4 _______________________________________________________________________________________

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4554 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

MIN MAX

PARAMETER SYMBOL CONDITIONS T

A

TYP

(Note 2)

5

UNITS

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

R

R

ON

FLAT(ON)

NOS_, NOG Off-Leakage

Current

COMS, COMG Off-Leakage

Current

COMS, COMG On-Leakage

Current

Charge Injection

LOGIC INPUT

IN_, EN Input Logic

Threshold High

I

I

I

I

I

I

NOS_(OFF)

NOG_(OFF)

COMS(OFF)

COMG(OFF)

COMS(ON)

COMG(ON)

Q

,

,

,

V

IN_H

,

V

ENH

IN_, EN Input Logic

Threshold Low

V

IN_L

,

V

ENL

IN_, EN Input Current Logic

High or Low

I

IN_H

, I

IN_L

,

I

ENH

, I

ENL

SWITCH DYNAMIC CHARACTERISTICS

V

COM_

= ±10V, I

COM_

= 1mA

V

COM_

= +5V, 0V, -5V; I

COM_

= 1mA

V+ = 16.5V; V- = -16.5V;

V

COM_

= ±10V; V

NOS_,

V

NOG_

±

V+ = 16.5V; V- = -16.5V;

±

V

COM_

= ±10V; V

NOS_,

V

NOG_

= 10V

V+ = 16.5V, V- = -16.5V,

V

COM_

= ±10V

V

COM_

= 0, Figure 13

V

EN

= 0 or VL

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

C, E

-0.25

-2.5

-0.25

-2.5

-0.5

-5.0

0.8

-0.5

1.5

0.01

0.01

0.02

4

1.6

1.6

0.03

9

10

5

6

0.25

2.5

0.25

2.5

0.5

5.0

2.4

0.5

Ω nA nA nA pC

V

V

µA

Turn-On Time (Force)

Turn-On Time

(Sense-Guard)

Turn-Off Time (Force)

Turn-Off Time

(Sense-Guard)

Enable Time On

Enable Time Off

NOF_ Off-Capacitance

NOS_, NOG_

Off-Capacitance

COMF Off-Capacitance

COMS, COMG

Off-Capacitance t

ON t

ON t

OFF t

OFF t

EN t

EN

C

OFF

C

OFF

C

OFF

C

OFF

V

COM_

= ±10V, R

L

= 300

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

,

Figure 10

V

COM_

= ±10V, R

L

= 300

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

,

Figure 10

V

COM_

= ±10V, R

L

= 300

,

Figure 11

V

COM_

= ±10V, R

L

= 300

,

Figure 11

V

NOF

= GND, f = 1MHz, Figure 14

V

NOS_,

V

NOG_

= GND; f = 1MHz;

Figure 14

V

COMF

= GND, f = 1MHz, Figure 14

V

COMS_,

V

COMG

_= GND; f = 1MHz;

Figure 14

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

+25°C

+25°C

+25°C

135

135

170

135

310

170

22

9

29

9

325

225

275

500

600

300

400

275

325

225

275

275 ns ns ns ns ns ns pF pF pF pF

_______________________________________________________________________________________ 5

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4554 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

COMF On-Capacitance

COMS, COMG

On-Capacitance

Total Harmonic Distortion

(Force)

C

ON

C

ON

THD

V

COMF

= GND, f = 1MHz,

Figure 14

V

COMS,

V

COMG_

= GND; f = 1MHz;

Figure 14

+25°C

+25°C

+25°C

107

29

0.007

pF pF

%

Off Isolation (Force) V

ISO

R

IN_

= 50

, R

OUT

= 50

, f = 1MHz,

V

COM_

= 100mV

RMS

, Figure 15

+25°C -30 dB

POWER SUPPLY

Power-Supply Range V+, VL, V-

V

V+ Supply Current

V- Supply Current

VL Supply Current

Ground Current

I+

I-

I

L+

I

GND

VL

4.5V

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

±4.5

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

0.001

0.001

0.001

±20

1.0

5.0

1.0

5.0

1.0

5.0

1.0

5.0

µA

µA

µA

µA

ELECTRICAL CHARACTERISTICS—MAX4555 (±15V Supplies)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

6

ANALOG SWITCH (FORCE)

Analog Signal Range V

COM_

, V

NO_

(Note 3)

On-Resistance

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NC_ Off-Leakage Current

COM_ Off-Leakage Current

COM_ On-Leakage Current

Charge Injection

R

ON

R

ON

R

FLAT(ON)

I

NC_(OFF)

I

COM_(OFF)

I

COM_(ON)

Q

V

COM_

= ±10V, I

COM_

= 10mA

V

COM_

= ±10V, I

COM_

= 10mA

V

COM_

= +5V, 0V, -5V;

I

COM_

= 10mA

V+ = 16.5V, V- = -16.5V,

V

COM_

= ±10V, V

NO_

±

V+ = 16.5V, V- = -16.5V,

V

COM_

= ±10V, V

NO_

±

V+ = 16.5V, V- = -16.5V,

V

COM_

= ±10V

V

COM_

= 0, Figure 13

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

V-

-0.25

-2.5

-0.5

-5.0

-0.5

-10

3.8

0.3

0.05

0.03

0.03

0.06

100

V+

6

7

1

1.5

1

1.5

0.25

2.5

0.5

5.0

0.5

10

V

Ω nA nA nA pC

6 _______________________________________________________________________________________

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4555 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL

30

ANALOG SWITCH (SENSE-GUARD)

Analog Signal Range V

COM_

, V

NO_

(Note 3)

CONDITIONS T

A

MIN

V-

TYP

(Note 2)

MAX

UNITS

V

On-Resistance R

ON

V

COM_

= ±10V, I

COM_

= 10mA

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NC_ Off-Leakage Current

COM_ Off-Leakage Current

COM_ On-Leakage Current

R

ON

R

FLAT(ON)

I

NC_(OFF)

I

COM_(OFF)

I

NC_(ON)

V

COM_

= ±10V, I

COM_

= 10mA

V

COM_

= +5V, 0V, -5V;

I

COM_

= 10mA

V+ = 16.5V, V- = -16.5V,

±

V

COM_

= ±10V, V

NO_

= 10V

V+ = 16.5V, V- = -16.5V,

±

V

COM_

= ±10V, V

NO_

= 10V

V+ = 16.5V, V- = -16.5V,

V

NC_

= ±10V

V

COM_

= 0, Figure 13 Charge Injection

LOGIC INPUT

IN_ Input Logic Threshold

High

IN_ Input Logic Threshold

Low

V

V

Q

IN_H

IN_L

IN_ Input Current Logic

High or Low

I

IN_H

,

I

IN_L

SWITCH DYNAMIC CHARACTERISTICS

V

IN_

= 0.8V or 2.4V

Turn-On Time (Force)

Turn-On Time

(Sense-Guard)

Turn-Off Time (Force)

Turn-Off Time

(Sense-Guard)

COM_ Off-Capacitance

(Force)

COM_ On-Capacitance

(Sense-Guard)

COM_ On-Capacitance

(Force)

COM_ Off-Capacitance

(Sense-Guard) t

ON t

ON t

OFF t

OFF

C

OFF

C

ON

C

ON

C

OFF

V

COM_

= ±3V, R

L

= 300

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

,

Figure 10

V

COM_

= ±3V, R

L

= 300

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

,

Figure 10

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

C, E

+25°C

+25°C

+25°C

+25°C

-0.3

-2.5

-0.3

-2.5

-0.6

-5.0

0.8

-0.5

15

0.6

0.6

0.01

0.01

0.02

4

1.6

1.6

0.03

155

125

190

125

29

9

107

29

275

325

225

275

275

325

225

275

V+

30

45

4

5

5

6

0.3

2.5

0.3

2.5

0.6

5.0

2.4

0.5

Ω nA nA nA pC

V

V

µA ns ns ns ns pF pF pF pF

_______________________________________________________________________________________ 7

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4555 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

NC_ Off-Capacitance

(Force)

NC_ Off-Capacitance

(Sense-Guard)

Total Harmonic Distortion

(Force)

Off Isolation (Force)

(Note 6)

POWER SUPPLY

Power-Supply Range

C

OFF

C

OFF

THD

V

ISO

V+, VL, V-

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

V

COM_,

V

NO_

= GND; f = 1MHz;

Figure 14

R

IN

= 50

, R

OUT

= 50

, f = 1MHz,

V

COM_

= 100mV

RMS

, Figure 15

+25°C

+25°C

+25°C

+25°C

22

9

0.007

-38 pF pF

% dB

V

V+ Supply Current

V- Supply Current

VL Supply Current

Ground Current

I+

I-

I

L+

I

GND

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

V+ = 16.5V; V- = -16.5V;

V

EN,

V

IN_

= 0 or V+

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

±4.5

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

0.001

0.001

0.001

0.001

5.0

1.0

5.0

1.0

5.0

±20

1.0

5.0

1.0

µA

µA

µA

µA

ELECTRICAL CHARACTERISTICS—MAX4556 (±15V Supplies)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

6

ANALOG SWITCH (FORCE)

Analog Signal Range

V

COM1

,

V

NO1

, V

NC1

(Note 3) C, E

VV+ V

On-Resistance

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NO1, NC1 Off-Leakage

Current

COM1 Off-Leakage Current

COM1 On-Leakage Current

Charge Injection

R

ON

R

ON

R

FLAT(ON)

I

NO1(OFF)

,

I

NC1(OFF)

I

COM1(OFF)

I

COM1(ON)

Q

V

COM1

= ±10V, I

COM1

= 10mA

V

COM1

= ±10V, I

COM1

= 10mA

V

COM1

= +5V, 0V, -5V;

I

COM1

= 10mA

V+ = 16.5V; V- = -16.5V;

V

COM1

= ±10V; V

NO1,

V

NC1

±

V+ = 16.5V, V- = -16.5V,

V

COM1

= ±10V, V

NO1

±

V+ = 16.5V, V- = -16.5V,

V

COM1

= ±10V

V

COM1

= 0, Figure 13

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

-0.25

-2.5

-0.5

-5.0

-0.5

-10

3.8

0.3

0.05

0.03

0.03

0.06

100

2.5

0.5

5.0

0.5

10

6

7

1

1.5

1

1.5

0.25

Ω nA nA nA pC

8 _______________________________________________________________________________________

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4556 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

60

ANALOG SWITCH (SENSE-GUARD)

Analog Signal Range

V

COM_

,

V

NO_

, V

NC_

(Note 3) C, E VV+ V

On-Resistance

On-Resistance Match

(Note 4)

On-Resistance Flatness

(Note 5)

NO_, NC Off-Leakage

Current

COM_ Off-Leakage Current

COM_ On-Leakage Current

Charge Injection

LOGIC INPUT

IN_ Input Logic Threshold

High

IN_ Input Logic Threshold

Low

R

ON

R

ON

R

FLAT(ON)

I

NO_(OFF)

,

I

NC_(OFF)

I

COM_(OFF)

I

COM_(ON)

Q

V

IN_H

V

IN_L

V

COM_

= ±10V, I

COM_

= 10mA

V

COM_

= ±10V, I

COM_

= 10mA

V

COM_

= +5V, 0V, -5V;

I

COM_

= 10mA

V+ = 16.5V; V- = -16.5V;

V

COM_

= ±10V; V

NO_,

V

NC_

±

V+ = 16.5V; V- = -16.5V;

V

COM_

= ±10V; V

NO_,

V

NC_

±

V+ = 16.5V, V- = -16.5V,

V

COM_

= ±10V

V

COM_

= 0, Figure 13

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

C, E

-0.25

-2.5

-0.25

-2.5

-0.5

-5.0

0.8

36

5

0.6

0.01

0.01

0.02

5

1.6

1.6

6

0.25

2.5

0.25

2.5

0.5

5.0

60

70

9

10

5

2.4

Ω nA nA nA pC

V

V

IN_ Input Current Logic

High or Low

I

IN_H

,

I

IN_L

SWITCH DYNAMIC CHARACTERISTICS

V

IN_

= 0 or VL C, E -0.5

0.03

0.5

µA

Transition Time (Force)

Transition Time

(Sense-Guard)

Break-Before-Make Time

NO1, NC1 Off-Capacitance

(Force)

COM1 On-Capacitance

(Force)

NO_, NC_ Off-Capacitance

(Sense-Guard)

COM_ On-Capacitance

(Sense-Guard)

Total Harmonic Distortion

(Force) t

TRANS t

TRANS t

BBM

C

OFF

C

ON

C

OFF

C

ON

THD

V

COM_

= ±10V, R

L

= 300

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

,

Figure 10

V

COM_

= ±10V, R

L

= 1k

, Figure 12

V

NO1,

V

NC1

= GND; f = 1MHz;

Figure 14

V

COM1

= GND, f = 1MHz,

Figure 14

V

NO_,

V

NC_

= GND; f = 1MHz;

Figure 14

V

COM_

= GND, f = 1MHz,

Figure 14

+25°C

C, E

+25°C

C, E

+25°C

+25°C

+25°C

+25°C

+25°C

+25°C

1

150

125

15

21

137

7

30

0.007

250

300

225

275 ns ns ns pF pF pF pF

%

Off Isolation (Force) V

ISO

R

IN

= 50

, R

OUT

= 50

, f = 1MHz,

V

COM_

= 100mV

RMS

, Figure 15

+25°C -30 dB

_______________________________________________________________________________________ 9

Force-Sense Switches

ELECTRICAL CHARACTERISTICS—MAX4556 (±15V Supplies) (continued)

(V+ = +15V, V- = -15V, VL = 5V, GND = 0V, V

IN_H

= 2.4V, V

IN_L

= 0.8V, T

A

= T

MIN to T

MAX

, unless otherwise noted. Typical values are at T

A

= +25°C.)

PARAMETER SYMBOL CONDITIONS T

A

MIN TYP

(Note 2)

MAX

UNITS

POWER SUPPLY

Power-Supply Range V+, VL, VV

V+ Supply Current

V- Supply Current

VL Supply Current

Ground Current

I+

I-

I

L+

I

GND

VL

4.5V

V+ = 16.5V, V- = -16.5V,

V

IN_

= 0 or VL

V+ = 16.5V, V- = -16.5V,

V

IN_

= 0 or VL

V+ = 16.5V, V- = -16.5V,

V

IN_

= 0 or VL

V+ = 16.5V, V- = -16.5V,

V

IN_

= 0 or VL

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

+25°C

C, E

±4.5

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

-1.0

-5.0

0.001

0.001

0.001

0.001

±20

1.0

5.0

1.0

5.0

1.0

5.0

1.0

5.0

µA

µA

µA

µA

Note 2:

The algebraic convention is used in this data sheet; the most negative value is shown in the minimum column.

Note 3:

Guaranteed by design.

Note 4:

R

ON

=

R

ON(MAX)

-

R

ON(MIN)

.

Note 5:

Resistance flatness is defined as the difference between the maximum and the minimum value of on-resistance as measured over the specified analog signal range.

10 ______________________________________________________________________________________

Force-Sense Switches

__________________________________________Typical Operating Characteristics

(V+ = +15V, V- = -15V, GND = 0V, T

A

= +25°C, unless otherwise noted.)

40

35

30

25

20

15

10

5

0

-15

SWITCH ON-RESISTANCE vs. V

COM

(DUAL SUPPLIES)

-10

MAX4554/MAX4556

SENSE & GUARD

MAX4555 SENSE

FORCE

-5 0

V

COM

(V)

5 10 15

6

5

4

3

2

1

0

-10

MAX4554

FORCE SWITCH ON-RESISTANCE vs. V

COM

AND TEMPERATURE

-5

T

A

= +85°C

T

A

= +25°C

T

A

= -40°C

0 5

V

COM

(V)

10 15 20

60

55

50

45

40

35

30

25

20

15

10

-15

SENSE/GUARD SWITCH ON-RESISTANCE vs. V

COM

AND TEMPERATURE

-10 -5

T

A

= +85°C

T

A

= +25°C

T

A

= -40°C

0

V

COM

(V)

5 10 15

100

SWITCH ON-RESISTANCE vs. V

COM

(SINGLE +15V SUPPLY)

MAX4554/MAX4556

SENSE & GUARD

100

10

1

ON-LEAKAGE CURRENT vs. TEMPERATURE

V+ = 15V,

V- = -15V,

V

COM

= 10V

FORCE

MAX4555 SENSE

10

0.1

SENSE & GUARD

0.01

FORCE

0.001

1

0 1 2 3 4 5 6 7 8

V

COM

(V)

9 10 11 12 13 14 15

100

10

OFF-LEAKAGE CURRENT vs. TEMPERATURE

V+ = 15V,

V- = -15V,

V

NC

OR V

V

COM

±

NO

= ±10V

= 10V

1

0.1

0.01

FORCE

SENSE & GUARD

0.001

0.0001

-50 -25 0 25 50

TEMPERATURE (°C)

75 100 125

60

40

20

0

-20

-40

-10

0.0001

-50 -25 0 25 50

TEMPERATURE (°C)

75 100

MAX4554

CHARGE INJECTION vs. V

COM

(+20V, -10V SUPPLIES)

125

100

FORCE

80

-5

SENSE & GUARD

0 5

V

COM

(V)

10 15 20

______________________________________________________________________________________ 11

Force-Sense Switches

____________________________________Typical Operating Characteristics (continued)

(V+ = +15V, V- = -15V, GND = 0V, T

A

= +25°C, unless otherwise noted.)

100

80

60

40

20

0

-20

-40

-15

MAX4555/MAX4556

CHARGE INJECTION vs. V

COM

(+15V SUPPLIES)

-10

FORCE

SENSE & GUARD

-5 0

V

COM

(V)

5 10 15

100

10

A: I+ = 16.5V

B: I- = -16.5V

C: I

L

= 5.5V

SUPPLY CURRENT

vs. TEMPERATURE

500

450

400

350

300

250

200

150

100

50

0

-40

MAX4554

ON/OFF/ENABLE TIMES vs.

TEMPERATURE (+20V, -10V SUPPLIES)

t

OFF

-15 t

EN(ON) t

EN(OFF) t

ON

10 35

TEMPERATURE (°C)

60 85

6

5

180

160

140

120

100

80

60

40

20

0

-40

MAX4555/4556

ON/OFF/TRANSITION TIMES vs.

TEMPERATURE (+20V/-10V SUPPLIES)

MAX4555 t

ON

/t

OFF

MAX4556 t

TRANS

-15 10 35

TEMPERATURE (°C)

60 85

LOGIC-LEVEL THRESHOLD vs. LOAD VOLTAGE

1 4

0.1

A

0.01

B

0.001

C

0.0001

-75

-55 -50 -25

0

25 50

TEMPERATURE (°C)

75 85 100

0

-10

-20

-30

-40

-90

-100

-110

-50

-60

-70

-80

-120

FORCE SWITCH FREQUENCY RESPONSE

MAX4554/5/6-13

0.1

1

ON LOSS

OFF LOSS

ON PHASE

10

FREQUENCY (MHz)

100

30

0

-30

-60

-90

-120

-150

1000

-180

180

150

120

90

60

3

2

1

100

10

0

0 5 10

VL (V)

15 20

FORCE SWITCH TOTAL HARMONIC

DISTORTION vs. FREQUENCY

V+ = +15V

V- = -15V

5Vp-p, 600

IN & OUT

25

1

0.1

0.01

0.001

10 100 1k

FREQUENCY (Hz)

10k 100k

12 ______________________________________________________________________________________

Force-Sense Switches

Pin Description

PIN

MAX4554 MAX4555 MAX4556

1 — —

2

3*

4

5

6*

7

8

9

11, 10

2, 15*,

10*, 7

3, 14, 11, 6

4

5

1, 16, 9, 8

1, 2

14*, 15, 16

3*

4

5

6*

7, 8

9, 10, 11

NAME

NOG1

NO3, NO2

NOS1

COM1, COM2

COM3, COM4

NOF1*

NC1, NC2,

NC3, NC4

NO1*

V-

GND

NOF2*

NC1*

NOS2

NC2, NC3

NOG2

EN

IN1, IN2,

IN3, IN4

FUNCTION

Analog Guard Channel 1 Normally Open Terminal

Analog Signal Normally Open Terminals

Analog Sense Channel 1 Normally Open Terminal

Analog Signal Common Terminals. COM2 and COM3 are low-resistance (force) switches on the MAX4555. COM1 is a low-resistance

(force) switch on the MAX4556.

Analog Force Channel 1 Normally Open Terminal

Analog Signal Normally Closed Pins. NC2 and NC3 are low-resistance

(force) switches.

Analog Force Signal Normally Open Terminal

Negative Analog Supply Voltage Input. Connect to GND for singlesupply operation.

Ground. Connect to digital ground. (Analog signals have no ground reference; they are limited to V+ and V-.)

Analog Force Channel 2 Normally Open Terminal

Analog Force Signal Normally Closed Terminal

Analog Sense Channel 2 Normally Open Terminal

Analog Signal Normally Closed Terminal

Analog Guard Channel 2 Normally Open Terminal

Enable Logic-Level Digital Input. Connect to GND to enable all switches.

Logic-Level Digital Inputs. See Truth Tables.

12

13

14*

15

16

12

13

12

13

VL

V+

COMF*

COMS

COMG

Logic-Level Positive Supply Input. Connect to logic (+5V) supply. Can be connected to V+ for single-supply operation.

Positive Analog Supply Voltage Input. Internally connected to substrate.

Analog Force Channel Common Terminal

Analog Sense Channel Common Terminal

Analog Guard Channel Common Terminal

* Indicates high-current, low-resistance (force) switch terminal.

Note:

NO_, NC_, and COM_ pins are identical and interchangeable. Any may be considered as an input or output; signals pass equally well in either direction.

______________________________________________________________________________________ 13

Force-Sense Switches

______________Force-Sense Philosophy

When a precise voltage must be applied to a load that draws appreciable current, the resistance of the conductors connecting the source and the load can degrade the load voltage. The resistance of the conductors forms a voltage divider with the load, so that the load voltage is lower than the source voltage. The greater the distance between the source and the load, and the greater the current or conductor resistance, the greater the degradation. The resulting signal reduction can be overcome and the signal at the load guaranteed by using a 4-wire technique known as Kelvin sensing, or force-sense.

The basic idea behind the force-sense philosophy is to use four wires, forcing a voltage or current through two high-current wires to the load, and measuring (sensing) the voltage with two separate wires that carry very low or negligible current. One of two basic configurations is used, depending on whether or not feedback is employed:

1) The sensed voltage can be completely independent of the forced voltage or current, as in the case of a

4-wire ohmmeter, where a constant current is forced through one pair of wires and the voltage at the resistor is measured by another pair.

2) The sensed voltage can be part of a feedback circuit to force the load voltage to the desired value, as in the case of a 4-wire power supply. (In rare cases, this method is also used to measure resistance; the source is forced to produce a desired voltage in the resistor, and the source current required to achieve this voltage is measured.)

In all cases, the resistance of the high-current conductors can be ignored and the sensed voltage is an accurate measure of the load (or resistor’s) voltage, despite appreciable voltage loss in the wires connecting the source and load.

There are two limitations to this scheme. First, the maximum source voltage (compliance) must be able to overcome the combined voltage loss of the load and the connecting wires. In other words, the conductors in the force circuit can have significant resistance, but there is a limit. Second, the impedance of the sensing circuit (typically a voltmeter, A/D converter, or feedback amplifier) must be very high compared to the load resistance and the sense wire resistance. These limitations are usually simple to overcome. The source compliance is usually required to be only a volt more than the load voltage, and the sense circuit usually has a multimegohm impedance. Typical 4-wire force-sense configurations are shown in Figure 1.

4-WIRE RESISTANCE MEASUREMENT (CONSTANT CURRENT)

FORCE CURRENT

VOLTAGE

MEASUREMENT

SENSE VOLTAGE

V

MEASURED

RESISTANCE

SENSE VOLTAGE

FORCE CURRENT

CURRENT SOURCE

WIRE AND TERMINAL RESISTANCE

VOLTAGE

MEASUREMENT

FEED-

BACK

V

4-WIRE POWER SUPPLY

FORCE CURRENT

SENSE VOLTAGE

SENSE VOLTAGE

FORCE CURRENT

CURRENT SOURCE

WIRE AND TERMINAL RESISTANCE

4-WIRE RESISTANCE MEASUREMENT (CONSTANT VOLTAGE)

V

FORCE VOLTAGE

FEED-

BACK

V

VOLTAGE

MEASUREMENT

VOLTAGE SOURCE

SENSE VOLTAGE

SENSE VOLTAGE

FORCE VOLTAGE

WIRE AND TERMINAL RESISTANCE

ARROWS INDICATE SIGNAL DIRECTION, NOT POLARITY

Figure 1. 4-Wire Force-Sense Measurements

14 ______________________________________________________________________________________

LOAD

MEASURED

RESISTANCE

Force-Sense Switches

__________________Guard Philosophy

When measuring a precise voltage from a high-resistance source, or when measuring a very small current or forcing it into a load, unwanted leakage currents can degrade the results. These leakage currents may exist in the insulation of wires connecting the source and the measuring device. Higher source voltages, higher source impedances, longer wires, lower currents, and higher temperatures further degrade the measurement.

The effect has both DC and low-frequency AC components; AC signals are generally capacitively coupled into the high-impedance source and wiring. The AC and DC effects are hard to separate, and are generally grouped under the designation “low-frequency noise.”

This signal degradation can be overcome and the measured signal guaranteed by using a 3-wire technique known as guarding.

A “guard,” “guard channel,” or “driven guard” is formed by adding a third wire to a 2-wire measurement. It consists of a physical barrier (generally the surrounding shield of a coaxial cable) that is actively forced to the same voltage as is being measured on its inner conductor. The forcing of the driven guard is from the output of a low-impedance buffer amplifier whose high-impedance input is connected to the source. The idea is not just to buffer or shield the signal with a low-impedance source but, by forcing the shield to the same potential as the signal, to also force the leakage currents between the signal and the outside world to extremely small values. Any unwanted leakage current from the source must first go through the coaxial-cable insulation to the shield. Since the shield is at the same potential, there is virtually no unwanted leakage current, regardless of the insulation resistance. The shield itself can have significant leakage currents to the outside world, but it is separated from the measured signal.

The physical positioning of the guard around the signal is extremely important in maintaining low leakage.

Since the guard can be at potentials far from ground, conventional coaxial cable is often replaced by triaxial cable (i.e., cable with a center conductor and two separate inner and outer shields). The signal is the center conductor, the inner shield is the guard, and the outer shield is the chassis ground. The outer shield isolates the inner driven guard from ground, physically protects the driven guard, and acts as a secondary Faraday shield for external noise.

The physical guard must be maintained continuously from the source to the measuring device, including paths on printed circuit boards, where the guard becomes extra traces surrounding the signal traces on both sides (and above and below the signal traces on multilevel boards.) This is one case where a ground plane is not appropriate. In extreme cases, such as with nano-voltmeters and femto-ammeters, printed circuit boards cannot be adequately shielded and are eliminated from the guarded signal paths altogether.

Figure 2 shows both the basic 3-wire guarded measurement and a 5-wire variation, used for balanced signals that are elevated from ground potential. The 5-wire configuration is really two 3-wire circuits sharing a common ground. Figure 2 also shows the configuration using triaxial cable.

____Force-Sense-Guard Philosophy

Force-sense measurements are combined with guarded measurements when a wide range of voltages and currents are encountered, or when voltage and current must be accurately measured or controlled simultaneously. This frequently occurs in automatic test equipment (ATE) and in some critical physical or chemical sensor applications where voltage and/or current measurements can span many decades. Two techniques are used: 8-wire and 12-wire.

8-Wire Measurements

Figure 3 shows an 8-wire guarded force-sense power supply. A precise voltage is forced to the load, and load current is sensed without interacting with the output voltage, and without unwanted leakage currents.

Separate twin-axial, or “twinax” cable is used for each of the positive and negative wires. Each cable has a twisted-pair of wires surrounded by a common shield, which is connected as the driven guard. Since the force and sense wires are at approximately the same potential, they can be protected by the same driven guard. In critical applications, two special 4-wire cables and connectors are substituted for the two twinax cables and separate ground wire. These cables add a second shield, which replaces the chassis-to-chassis ground wire and reduces noise.

Figure 3 shows current sensing with a fixed precision resistor and voltmeter, but other methods (such as op amps with feedback) are frequently employed, particularly if current limiting is required. One of the advantages of Figure 3’s circuit is that leakage in the current-sensing path has no effect on the output voltage.

The two diodes in the force-sense feedback path protect the force-sense amplifier from operating open loop if either the force or sense wires are disconnected from the load. These diodes must have both lower forward voltage and lower reverse leakage than the current being measured.

______________________________________________________________________________________ 15

Force-Sense Switches

GUARD AMPLIFIER

BASIC 3-WIRE GUARD CIRCUIT

DRIVEN GUARD

(COAX CABLE SHIELD)

BALANCED 5-WIRE GUARD CIRCUIT

GUARD AMPLIFIER

SENSE

VOLTAGE OR

CURRENT

LEAKAGE

CURRENT

VOLTAGE OR

CURRENT SOURCE

VOLTAGE OR

CURRENT SOURCE

GUARD AMPLIFIER

3-WIRE GUARD CIRCUIT USING TRIAX

TRIAX CABLE

SIGNAL

GUARD

GROUND

VOLTAGE OR

CURRENT SOURCE

LEAKAGE

CURRENT

TRIAX CABLE/CONNECTOR

CENTER WIRE

INNER SHEILD

OUTER SHEILD

SENSE

VOLTAGE OR

CURRENT

GUARD AMPLIFIER

DRIVEN GUARD

(COAX CABLE SHIELD)

LEAKAGE

CURRENT

LEAKAGE

CURRENT

DRIVEN GUARD

(COAX CABLE SHIELD)

SENSE

VOLTAGE

OR CURRENT

Figure 2. 3-Wire and 5-Wire Guarded Measurements

16 ______________________________________________________________________________________

Force-Sense Switches

8-WIRE PRECISION SOURCE-MONITOR

FORCE-SENSE AMPLIFIER

V+

CURRENT SENSE

V

V-

V+

GUARD AMPLIFIER

V-

V+

VOLTAGE SOURCE

V+

V-

LEAKAGE CURRENT

LEAKAGE CURRENT

+FORCE

+SENSE

+DRIVEN GUARD

TWINAX CABLE

LOAD

GUARD AMPLIFIER

V-

V+

V-

FORCE-SENSE AMPLIFIER

V

CURRENT SENSE

-DRIVEN GUARD

-SENSE

-FORCE

TWINAX CABLE

Figure 3. 8-Wire Guarded Force-Sense Measurements

Note that although the positive and negative circuits are identical, they are not redundant. Both are always used, even when one side of the load is grounded, because maintaining a precision output voltage requires losses in the ground leads to be corrected by a force-sense amplifier. If more than one power supply and load are operated together, and they have a common connection, this requirement becomes even more critical.

Separate 8-wire connections prevent current changes in one load from changing voltage in the other load.

12-Wire Measurements

Figure 4 shows a 12-wire circuit, which is an elaboration of the 8-wire system using separate driven guards for the force and sense wires. Four sets of triaxial cables and connectors are used. The extra wires are used for two reasons: 1) They provide better shielding by having separate chassis grounds on each cable, rather than separate ground wires external to the signal cables; 2) In test equipment, where connection changes are frequent, it is very convenient to use four triax connectors or two quadrax (dual triax) connectors for each load.

In addition, this method is slightly better for power supplies or measurements that switch between constant voltage and constant current, since separate driven guards reduce circuit capacitance. Also, when troubleshooting, it is convenient to be able to interchange force and sense leads.

______________________________________________________________________________________ 17

Force-Sense Switches

12-WIRE PRECISION SOURCE-MONITOR

+ FORCE-SENSE AMPLIFIER

V+

CURRENT SENSE

V

V-

V+

TRIAX CABLE

+FORCE

+GUARD

GROUND

V-

+ FORCE-GUARD AMPLIFIER

V+

+SENSE

GUARD AMPLIFIER

V-

TRIAX CABLE

+SENSE

+GUARD

GROUND

LEAKAGE CURRENT

LEAKAGE CURRENT

V+

VOLTAGE SOURCE

(OPTIONAL GROUND)

LOAD

V-

LEAKAGE CURRENT

V+

- SENSE-GUARD AMPLIFIER

V-

- FORCE-GUARD AMPLIFIER

V+

GROUND

- GUARD

-SENSE

TRIAX CABLE

LEAKAGE CURRENT

V+

V-

V+

V

V-

CURRENT SENSE

- FORCE-SENSE AMPLIFIER

GROUND

- GUARD

- FORCE

TRIAX CABLE

TRIAX CABLE/CONNECTOR

CENTER WIRE (FORCE/SENSE)

INNER SHEILD (GUARD)

OUTER SHEILD (GROUND)

Figure 4. 12-Wire Guarded Force-Sense Measurements

18 ______________________________________________________________________________________

Switching Guarded and

Force-Sense Signals

When a precision source or measurement must be connected sequentially to several circuits, all sense and guard connections must be switched simultaneously, and at least one of the force connections must be switched. To maintain safety and low noise levels, the ground (or chassis) connection should never be disconnected.

The force circuit switch should have low-resistance, high-current capability, but the sense and guard circuit switches require only moderate resistance and current capability. The sense and guard switches should have lower leakage than the lowest measured current.

CMOS switches should also be operated from power supplies higher than the highest circuit voltage to be switched.

_______________Detailed Description

The MAX4554/MAX4555/MAX4556 are CMOS analog

ICs configured as force-sense switches. Each part contains low-resistance switches for forcing current, and higher resistance switches for sensing a voltage or driving guard wires. Analog signals on the force, sense, or guard circuits can range from V- to V+. Each switch is completely symmetrical and signals are bidirectional; any switch terminal can be an input or output. The switches’ open or closed states are controlled by

TTL/CMOS-compatible input (IN_) pins.

The MAX4555 and MAX4556 are characterized and guaranteed only with ±15V supplies, but they can operate from a single supply up to +44V or non-symmetrical supplies with a voltage totaling less than +44V. The

MAX4554 is fully characterized for operation from ±15V supplies, and it is also fully specified for operation with

+20V and -10V supplies. A separate logic supply pin,

VL, allows operation with +5V or +3V logic, even with unusual V+ values. The negative supply pin, V-, must be connected to GND for single-supply operation.

The MAX4554 contains two force switches, two sense switches, and two guard switches configured as two

3PST switches. The two switches operate independently of one another, but they have a common connection, allowing one source to be connected simultaneously to two loads, or two sources to be connected to one load.

An enable pin, EN, turns all switches off when driven to logic high. The MAX4554 is also fully specified for operation with +20V and -10V supplies. The MAX4555 contains four independent SPDT, NC switches; two are force switches and two are sense switches. The

MAX4556 contains three independent SPDT switches; one is a force switch and two are sense switches.

Force-Sense Switches

Switch Resistances

Each IC contains four internal switches: four low-current sense-guard switches and two high-current force switches. Each sense-guard switch has an on-resistance of approximately 60

, while each force switch has an on-resistance of approximately 6

. The

MAX4555’s two low-current sense-guard switches are connected in parallel to produce lower on-resistance and allow higher current.

Power-Supply Considerations

Overview

The MAX4554/MAX4555/MAX4556’s construction is typical of most CMOS analog switches. They have four supply pins: V+, V-, VL, and GND. V+ and V- are used to drive the internal CMOS switches and set the analog voltage limits on any switch. Reverse ESD protection diodes are internally connected between each analog and digital signal pin and both V+ and V-. If any signal exceeds V+ or V-, one of these diodes will conduct. During normal operation these reverse-biased ESD diodes leak, forming the only current drawn from the signal paths.

Virtually all the analog leakage current comes through the ESD diodes to V+ or V-. Although the ESD diodes on a given signal pin are identical, and therefore fairly well balanced, they are reverse biased differently. Each is biased by either V+ or V- and the analog signal. This means their leakages vary as the signal varies. The difference in the two diode leakages from the signal path to the V+ and V- pins constitutes the analog-signal-path leakage current. All analog leakage current flows to the supply terminals, not to the other switch terminal. This explains how both sides of a given switch can show leakage currents of either the same or opposite polarity.

There is no connection between the analog signal paths and GND or VL. The analog signal paths consist of an N-channel and P-channel MOSFET with their sources and drains paralleled, and their gates driven out of phase to V+ and V- by the logic-level translators.

VL and GND power the internal logic and logic-level translator and set the input logic threshold. The logiclevel translator converts the logic levels to switched V+ and V- signals for driving the gates of the analog switches. This drive signal is the only connection between GND and the analog supplies. V+ and V- have

ESD-protection diodes to GND. The logic-level inputs

(IN_, and EN) have ESD protection to V+ and V-, but not to GND; therefore, the logic signal can go below

GND (as low as V-) when bipolar supplies are used.

The logic-level threshold V

IN is CMOS and TTL compatible when VL is between 4.5V and 36V (see Typical

Operating Characteristics).

______________________________________________________________________________________ 19

Force-Sense Switches

Increasing V- has no effect on the logic-level thresholds, but it does increase the drive to the internal Pchannel switches, reducing the overall switch on-resistance. V- also sets the negative limit of the analog signal voltage.

Bipolar-Supply Operation

The MAX4554/MAX4555/MAX4556 operate with bipolar supplies between ±4.5V and ±18V. However, since all factory characterization is done with ±15V supplies

(and +20V, -10V for MAX4554), operation at other supplies is not guaranteed. The V+ and V- supplies need not be symmetrical, but their sum cannot exceed the absolute maximum rating of 44V (see Absolute Maximum Ratings). VL must not exceed V+.

Single-Supply Operation

The MAX4554/MAX4555/MAX4556 operate from a single supply between +4.5V and +44V when V- is connected to GND. All of the bipolar precautions must be observed.

__________Applications Information

Switching 4-Wire

Force-Sense Circuits

Figure 5 shows how to switch a single voltage or current source between two loads using two MAX4555s. A single CMOS inverter ensures that only one switch is on at a time. On each MAX4555, switches 2 and 3 are the high-current switches, so they should be used for force circuits. By interchanging loads and sources, the circuit can be reversed to switch two sources to a single load.

Additional MAX4555s and loads or sources can be added to expand the circuit, but additional IN_ address decoding must be incorporated.

FORCE

SENSE

FEEDBACK

V

VOLTAGE/CURRENT SOURCE

SENSE

FORCE

IN

0

1

LOGIC

LOAD

2

1

IN

CMOS INVERTER

COM4

COM3

IN2

IN1

IN4

IN3

COM2

COM1

V+ V-

MAX4555

VL

NC2

NC1

COM4

COM3

IN2

IN1

IN4

IN3

COM2

COM1

V+ V-

MAX4555

VL

NC2

NC1

NC4

NC3

GND

LOAD1

LOAD2

NC4

NC3

GND

Figure 5. Using the MAX4555 to Switch 4-Wire Force-Sense Circuits from One Source to Two Loads

20 ______________________________________________________________________________________

Figure 6 shows how to switch a single voltage or current source between two loads using the MAX4554 or

MAX4556. By interchanging loads and sources, the circuits can be reversed so that they switch two sources to a single load. The two loads are electrically connected together at one point, but may be physically separated. This means that one force wire does not need to be switched, but the corresponding sense wires do.

The MAX4554 has independent 3PST, NO switches driven out of phase by an external CMOS inverter, so that one switch is on while the other is off. If both switches were turned on at the same time, both loads would be connected, and the resulting voltage at either load

Force-Sense Switches

would be close to (but not exactly equal to) the desired value; this would not cause any damage to the device.

Switching 3-Wire Guarded Circuits

Figure 7 shows how to switch a single guarded voltage or current source between two loads using the

MAX4554 or MAX4556. By interchanging loads and sources, the circuits can be reversed to switch two sources to a single load. If the loads have a common connection, the switch to that node can be eliminated.

Note that these circuits use sense (high-resistance) switches to switch the common wire. This is permissible only if the load currents are very low. If the currents are high, the common connection should not be switched unless another force switch is substituted.

FORCE

SENSE

FEEDBACK

V

SENSE

FORCE

VOLTAGE/CURRENT SOURCE

IN

0

1

LOGIC

LOAD

1

2

FORCE

SENSE

FEEDBACK

V

SENSE

FORCE

VOLTAGE/CURRENT SOURCE

IN

0

1

LOGIC

LOAD

1

2

V+ VVL

COM1

COM2

COM3

MAX4556

IN

IN1

IN2

IN3

GND

IN

FCOM

SCOM

GCOM

V+ V-

MAX4554

VL

NOF1

NOF2

NOS1

NOS2

IN1

NOG2

NOG1

GND

EN

IN2

CMOS INVERTER

NC1

NO1

NC2

NO2

NC3

NO3

LOAD2

LOAD1

LOAD2

LOAD1

Figure 6. Using the MAX4554/MAX4556 to Switch 4-Wire Force-Sense Circuits from One Source to Two Loads

______________________________________________________________________________________ 21

Force-Sense Switches

V+ VVL

GUARD AMPLIFIER

COM1

COM2

COM3

MAX4556

NC1

NO1

NC2

NO2

NC3

NO3

LOAD2

VOLTAGE OR

CURRENT SOURCE

IN

0

1

LOGIC

LOAD

1

2

IN

IN1

IN2

IN3

GND

GUARD AMPLIFIER

GCOM

FCOM

SCOM

V+ V-

MAX4554

VL

NOG1

NOG2

NOF1

NOF2

IN1

NOS1

NOS2

GND

EN

VOLTAGE OR

CURRENT SOURCE

IN

0

1

LOGIC

LOAD

1

2

IN

IN2

CMOS INVERTER

Figure 7. Using the MAX4554/MAX4556 to Switch 3-Wire Guarded Circuits from One Source to Two Loads

LOAD2

LOAD1

LOAD1

22 ______________________________________________________________________________________

Figure 8 shows how to switch a single guarded voltage or current source between two grounded loads using a

MAX4555. By interchanging loads and sources, the circuits can be reversed so that two sources are switched to a single load.

Switching 8-Wire Guarded Circuits

Figure 9 shows how to switch a single 8-wire guarded force-sense voltage or current source between two loads using two MAX4556s or two MAX4554s. By interchanging loads and sources, the circuits can be reversed so that they switch two sources to a single load. The two loads are shown isolated from each another, but if they have a common connection then the circuit must remain as shown in order to maintain accurate load voltage.

Force-Sense Switches

High-Frequency Performance

Although switching speed is restricted, once a switch is in a steady state it exhibits good RF performance. In

50

Ω systems, signal response is reasonably flat up to

50MHz (see Typical Operating Characteristics). The force switches have lower on-resistance, so their insertion loss in 50

Ω systems is lower. Above 20MHz, the on-response has several minor peaks that are highly layout dependent. The problem with high-frequency operation is not turning the switches on, but turning them off. The off-state switches act like capacitors and pass higher frequencies with less attenuation. At

10MHz, off-isolation between input or output signals is approximately -30dB in 50

Ω systems, degrading

(approximately 20dB per decade) as frequency increases. Higher circuit impedances also degrade offisolation.

GUARD AMPLIFIER

COM1

COM2

V+ V-

MAX4555

VL

NC1

NC2

COM3

COM4

IN1

IN2

IN3

IN4

NC3

NC4

GND

VOLTAGE OR

CURRENT SOURCE

IN

0

1

LOGIC

LOAD

2

1

IN

Figure 8. Using the MAX4555 to Switch 3-Wire Guarded Circuits from One Source to Two Loads

LOAD1

LOAD2

______________________________________________________________________________________ 23

Force-Sense Switches

COM1

COM2

COM3

IN1

IN2

IN IN3

IN

COMG

COMF

COMS

IN1

V+

V+

MAX4556

MAX4554

V-

V-

VL

VL

IN2

CMOS INVERTER

LOGIC

IN A,B LOAD

0

1

2

1

NOG1

NOG2

NOF1

NOF2

NOS1

NOS2

EN

GND

NC1

NO1

NC2

NO2

NC3

NO3

GND

FORCE-SENSE AMPLIFIER

V+

CURRENT SENSE

V-

V+

V-

V

GUARD AMPLIFIER

VOLTAGE SOURCE

V+

V+

V-

V+ VVL

MAX4556

COM1

COM2

COM3

INA

IN1 IN2 IN3

NC1

NC2

NC3

NO1

NO2

NO3

GND

V+

LEAKAGE

CURRENT

LEAKAGE

V-

CURRENT

VL

V-

V+

V-

FORCE-SENSE

AMPLIFIER

V+

GUARD AMPLIFIER

V

CURRENT SENSE

LOGIC

IN A,B LOAD

0

1

1

2

COM1

MAX4556

COM2

COM3

NC1

NC2

NC3

NO1

NO2

NO3

GND

INA

IN1 IN2 IN3

V+ VVL

CURRENT SENSE

V-

V+

V-

V

GUARD AMPLIFIER

VOLTAGE SOURCE

V+

V+

V-

INB

COMF

COMS

COMG

IN1

MAX4554

IN2

NC1

NC2

NC3

NO1

NO2

NO3

EN

GND

LEAKAGE

CURRENT

V+ V-

LEAKAGE

CURRENT

VL

V-

V+

V-

FORCE-SENSE

AMPLIFIER

GUARD AMPLIFIER

V

CURRENT SENSE

LOGIC

IN A,B LOAD

0

1

2

1

INB

COMG

COMS

COMF

MAX4554

IN1 IN2

NOG1

NOS1

NOF1

NOG2

NOS2

NOF2

EN

GND

TWINAX CABLE

+FORCE

+SENSE

+DRIVEN GUARD

LOAD 1

-DRIVEN GUARD

-SENSE

-FORCE

TWINAX CABLE

TWINAX CABLE

+FORCE

+SENSE

+DRIVEN GUARD

LOAD 1

-DRIVEN GUARD

-SENSE

-FORCE

TWINAX CABLE

Figure 9. Switching 8-Wire Guarded Force-Sense Measurements from One Precision Source-Monitor to Two Loads

24 ______________________________________________________________________________________

LOAD 2

LOAD 2

Force-Sense Switches

______________________________________________Test Circuits/Timing Diagrams

V+ VL

V+

VL

NO_ OR NC_

V

IN_

IN_

50

EN

MAX4554

MAX4555

MAX4556

COM_

GND

V-

V-

V+

300

V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

Figure 10. Address Transition Time

V+

VL

ADDRESS

SELECT

VL

V

EN

V+ VL

NO_

IN_

EN

MAX4554

GND

COM_

V-

50

V-

V+

300

V

OUT

35pF

V

OUT

35pF

V

IN_

VL

0V

V

OUT

V+

0V t

OFF

V

EN

VL

0V

V+

V

OUT

0V t

TRANS

50%

50%

90%

90%

90% t

ON

90% t

TRANS

V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

Figure 11. Enable Transition Time

V+ VL

V

IN_

IN_

V+

50

MAX4556

VL

NO_

NC_

COM_

GND

V-

V-

V+

300

V

OUT

35pF

V

IN_

V+

0V

V

NO_, NC_

V

OUT

50%

80% t

R

< 5ns t

F

< 5ns

0V t

OPEN

V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

Figure 12. Break-Before-Make Interval

______________________________________________________________________________________ 25

Force-Sense Switches

_________________________________Test Circuits/Timing Diagrams (continued)

V+ VL

V

IN_

IN_

V+

50

VL

NO_ OR NC_

EN

MAX4554

MAX4555

MAX4556

GND

COM_

V-

V-

C

L

1000pF

V

OUT

V

IN

V

OUT

VL

0V

V

OUT

V

OUT

IS THE MEASURED VOLTAGE DUE TO CHARGE TRANSFER

ERROR Q WHEN THE CHANNEL TURNS OFF.

Q =

V

OUT

x C

L

V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

Figure 13. Charge Injection

ADDRESS

SELECT

VL

V+ VL

V+ VL

IN_

EN

MAX4554

MAX4555

MAX4556

GND

NO_

NC_

COM_

V-

V-

1MHz

CAPACITANCE

ANALYZER

Figure 14. COM_, NO_, NC_ Capacitance

V+ 10nF

VL 10nF

ADDRESS

SELECT

VL

V+

VL

COM_

IN_

EN

MAX4554

MAX4555

MAX4556

NO_, NC_

GND V-

V

IN

V

OUT

50

MEAS.

NETWORK

ANALYZER

50

REF

OFF ISOLATION = 20 log

V

OUT

V

IN

ON LOSS = 20 log

V

OUT

V

IN

CROSSTALK = 20 log

V

OUT

V

IN

50

50

10nF

V-

MEASUREMENTS ARE STANDARDIZED AGAINST SHORT AT SOCKET TERMINALS. OFF ISOLATION IS MEASURED BETWEEN COM_ AND "OFF" NO_ OR NC_ TERMINALS.

ON LOSS IS MEASURED BETWEEN COM_ AND "ON" NO_ OR NC_ TERMINALS. CROSSTALK IS MEASURED BETWEEN COM_ TERMINALS WITH ALL SWITCHES ON.

SIGNAL DIRECTION THROUGH SWITCH IS REVERSED; WORST VALUES ARE RECORDED. V- IS CONNECTED TO GND (0V) FOR SINGLE-SUPPLY OPERATION.

Figure 15. Frequency Response, Off-Isolation, and Crosstalk

26 ______________________________________________________________________________________

Force-Sense Switches

__________Pin Configurations/Functional Diagrams/Truth Tables (continued)

TOP VIEW

MAX4555

IN1 1

COM1 2

NC1 3

V4

GND 5

NC4 6

COM4 7

IN4 8

16 IN2

15 COM2*

14 NC2*

13 V+

12 VL

11 NC3*

10 COM3

9 IN3

DIP/SO

IN_

MAX4555

SWITCH

0

1

ON

OFF

SWITCH POSITIONS SHOWN WITH IN_ = LOW

*INDICATES HIGH-CURRENT, LOW-RESISTANCE FORCE SWITCH

MAX4556

NO3 1

N02

2

NO1*

3

V4

GND 5

NC1* 6

NC2 7

NC3 8

DIP/SO

IN_

MAX4556

COM_

0

1

NC_

NO_

16 COM3

15

COM2

14

COM1*

13 V+

12 VL

11 IN1

10 IN2

9 IN3

Ordering Information (continued)

PART

MAX4555

CPE

MAX4555CSE

MAX4555C/D

MAX4555EPE

MAX4555ESE

MAX4556

CPE

MAX4556CSE

MAX4556C/D

MAX4556EPE

MAX4556ESE

* Contact factory for availability.

TEMP. RANGE

0°C to +70°C

0°C to +70°C

0°C to +70°C

-40°C to +85°C

-40°C to +85°C

0°C to +70°C

0°C to +70°C

0°C to +70°C

-40°C to +85°C

-40°C to +85°C

PIN-PACKAGE

16 Plastic DIP

16 Narrow SO

Dice*

16 Plastic DIP

16 Narrow SO

16 Plastic DIP

16 Narrow SO

Dice*

16 Plastic DIP

16 Narrow SO

______________________________________________________________________________________ 27

Force-Sense Switches

_________________________________________________________________________Chip Topographies

NOG1

MAX4554

COMG

IN1

MAX4555

IN2

NOS1

NOF1

COMS

COM1

NC1

COM2

V-

GND

COMF

V+

0.190"

(4.83mm)

V-

GND

NC2

V+

0.190"

(4.83mm)

NOF2

NOS2

VL

IN1

IN2

NC4

COM4

VL

NC3

COM3

NOG2

0.086"

(2.18mm)

EN

IN4

0.086"

(2.18mm)

IN3

NO3

MAX4556

COM3

NO2

NO1

COM2

V-

GND

COM1

V+

0.190"

(4.83mm)

VL

NC1

NC2

IN1

IN2

NC3

0.086"

(2.18mm)

IN3

TRANSISTOR COUNT: 197

SUBSTRATE IS INTERNALLY CONNECTED TO V+

28 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

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