General Description Features

General Description Features

MAX7322

EVALUATION KIT AVAILABLE

I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

General Description

The MAX7322 2-wire serial-interfaced peripheral features four push-pull outputs and four input ports with selectable internal pullups. Input ports are overvoltage protected to

+6V and feature transition detection with interrupt output.

The four input ports are continuously monitored for state changes (transition detection). The interrupt is latched, allowing detection of transient changes. Any combination of inputs can be selected using the interrupt mask to assert the open-drain INT output. When the MAX7322 is subsequently accessed through the serial interface, any pending interrupt is cleared.

The four push-pull outputs are rated to sink 20mA, and are capable of driving LEDs.

The RST input clears the serial interface, terminating any

I

2

C communication to or from the MAX7322.

The MAX7322 uses two address inputs with four-level logic to allow 16 I

2

C slave addresses. The slave address also sets the power-up default logic state for the four output ports, and enables or disables internal 40kΩ pullups for the input ports.

The MAX7322 is one device in a family of pin-compatible port expanders with a choice of input ports, open-drain I/O ports, and push-pull output ports (see Table 1).

The MAX7322 is available in 16-pin QSOP and TQFN packages, and is specified over the -40°C to +125°C automotive temperature range.

Applications

● Cell Phones

● SAN/NAS

● Servers

Pin Configurations

TOP VIEW

12

SDA 13

11

● Notebooks

● Satellite Radio

10 9

V+ 14

MAX7322

AD0 15

RST 16

+

1

*EP

2 3 4

8

7

I5

I4

6

GND

5 I3

TQFN

(3mm x 3mm)

Pin Configurations continued at end of data sheet.

Features

● 400kHz I

2

C Serial Interface

● +1.71V to +5.5V Operation Voltage

● 4 Push-Pull Output Ports Rated at 20mA Sink

Current

● 4 Input Ports with Maskable, Latching Transition

Detection

● Input Ports are Overvoltage Protected to +6V

● Transient Changes are Latched, Allowing

Detection Between Read Operations

● INT Output Alerts Change on Any Selection of Inputs

● AD0 and AD2 Inputs Select from 16 Slave Addresses

● Low 0.6µA (typ) Standby Current

● -40°C to +125°C Operating Temperature Range

Ordering Information

PART TEMP RANGE PIN-PACKAGE

TOP

MARK

— MAX7322AEE+ -40°C to +125°C 16 QSOP

MAX7322ATE+ -40°C to +125°C

16 TQFN-EP*

(3mm x 3mm)

+Denotes a lead(Pb)-free/RoHS-compliant package.

*EP = Exposed pad.

ADD

Selector Guide

PART INPUTS INTERRUPT

OPEN-

DRAIN

OUTPUTS

MAX7319 8

MAX7320 —

MAX7321 Up to 8

MAX7322 4

MAX7323 Up to 4

MAX7328 Up to 8

MAX7329 Up to 8

Yes

Yes

Up to 8

Up to 4

Up to 8

Up to 8

PUSH-PULL

OUTPUTS

4

8

4

Typical Application Circuit and Functional Diagram appear at end of data sheet.

19-3787; Rev 2; 5/14

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Absolute Maximum Ratings

(All voltages referenced to GND.)

Supply Voltage V+ ...................................................-0.3V to +6V

SCL, SDA, AD0, AD2, RST, INT, I2–I5 ...................-0.3V to +6V

O0, O1, O6, O7 ............................................... -0.3 to V+ + 0.3V

O0, O1, O6, O7 Output Current .......................................±25mA

SDA Sink Current .............................................................. 10mA

INT Sink Current.................................................................10mA

Total V+ Current .................................................................50mA

Total GND Current ...........................................................100mA

Continuous Power Dissipation (T

A

= +70°C)

QSOP (derate 8.3mW/°C above +70°C) .....................667mW

TQFN (derate 15.6mW/°C above +70°C)..................1250mW

Operating Temperature Range ......................... -40°C to +125°C

Junction Temperature ......................................................+150°C

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

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

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.

DC Electrical Characteristics

(V+ = +1.71V to +5.5V, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T

A

= +25°C.) (Note 1)

PARAMETER

Operating Supply Voltage

Power-On Reset Voltage

Standby Current

(Interface Idle)

Supply Current

(Interface Running)

Input High Voltage

SDA, SCL, AD0, AD2, RST, I2–I5

Input Low Voltage

SDA, SCL, AD0, AD2, RST, I2–I5

Input Leakage Current

SDA, SCL, AD0, AD2, RST, I2–I5

Input Capacitance

SDA, SCL, AD0, AD2, RST, I2–I5

SYMBOL

V

+

V

POR

V+ falling

I

STB

I

+

V

IH

V

IL

I

IH

, I

IL

CONDITIONS

SCL and SDA and other digital inputs at V+ f

SCL

= 400kHz; other digital inputs at V+

V+ < 1.8V

V+ ≥ 1.8V

V+ < 1.8V

V+ ≥ 1.8V

SDA, SCL, AD0, AD2, RST, at V+ or

GND, internal pullup disabled

MIN

1.71

0.8 x V+

0.7 x V+

-0.2

TYP

0.6

23

10

MAX

5.50

1.6

1.5

55

0.2 x V+

0.3 x V+

+0.2

UNITS

V

V

µA

µA

V

V

µA pF

Output Low Voltage

O0, O1, O6, O7

Output High Voltage

O0, O1, O6, O7

Output Low Voltage SDA

Output Low Voltage INT

Port Input Pullup Resistor

V

V

OL

OH

V+ = +1.71V, I

SINK

= 5mA

V+ = +2.5V, I

SINK

= 10mA

V+ = +3.3V, I

SINK

= 15mA

V+ = +5V, I

SINK

= 20mA

V+ = +1.71V, I

SOURCE

= 2mA

V+ = +2.5V, I

SOURCE

= 5mA

V+ = +3.3V, I

SOURCE

= 5mA

V+ = +5V, I

SOURCE

= 10mA

V

OLSDA

I

SINK

= 6mA

V

OLINT

I

SINK

= 5mA

R

PU

90 180

110 210

130

140

V+ - 250 V+ - 30

230

250

V+ - 360 V+ - 70

V+ - 260 V+ - 100

V+ - 360 V+ - 120

25

130

40

250

250

55 mV mV mV mV kW www.maximintegrated.com

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2

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Port and Interrupt

INT

Timing Characteristics

(V+ = +1.71V to +5.5V, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T

A

= +25°C.) (Note 1)

PARAMETER

Port Output Data Valid

Port Input Setup Time

Port Input Hold Time

INT Input Data Valid Time

INT Reset Delay Time from STOP

INT Reset Delay Time from

Acknowledge

SYMBOL

t

PPV t

PSU t

PH t

IV t

IP t

IR

C

L

≤ 100pF

C

L

≤ 100pF

C

L

≤ 100pF

C

L

≤ 100pF

C

L

≤ 100pF

C

L

≤ 100pF

CONDITIONS MIN

0

4

TYP MAX

4

4

4

4

UNITS

µs

µs

µs

µs

µs

µs

Timing Characteristics

(V+ = +1.71V to +5.5V, T

A

= -40°C to +125°C, unless otherwise noted. Typical values are at V+ = +3.3V, T

A

= +25°C.) (Note 1)

PARAMETER

Serial-Clock Frequency

Bus Free Time Between a STOP and a START Condition

Hold Time (Repeated) START

Condition

Repeated START Condition Setup

Time

STOP Condition Setup Time

Data Hold Time

Data Setup Time

SCL Clock Low Period

SCL Clock High Period

Rise Time of Both SDA and SCL

Signals, Receiving

Fall Time of Both SDA and SCL

Signals, Receiving

Fall Time of SDA, Transmitting

Pulse Width of Spike Suppressed

SYMBOL

f

SCL t

BUF t

HD, STA t

SU, STA t

SU, STO t

HD, DAT

(Note 2) t

SU, DAT t

LOW t

HIGH t

R t

F t

F,TX t

SP

(Notes 3, 4)

(Notes 3, 4)

(Notes 3, 4)

(Note 5)

CONDITIONS MIN

1.3

0.6

0.6

0.6

100

1.3

0.7

TYP

20 +

0.1C

b

20 +

0.1C

b

20 +

0.1C

b

50

MAX

400

0.9

300

300

250

UNITS

kHz

µs

µs

µs ns ns ns ns

µs

µs ns

µs

µs

Capacitive Load for Each Bus Line C b

(Note 3) 400 pF

RST Pulse Width t

W

500 ns

RST Rising to START Condition

Setup Time t

RST

1 µs

Note 1: All parameters are tested at T

A

= +25°C. Specifications over temperature are guaranteed by design.

Note 2: A master device must provide a hold time of at least 300ns for the SDA signal (referred to V

IL

of the SCL signal) in order to bridge the undefined region of SCL’s falling edge.

Note 3: Guaranteed by design.

Note 4: C b

= total capacitance of one bus line in pF. t

R

and t

F

measured between 0.3 x V+ and 0.7 x V+ with I

Note 5: Input filters on the SDA and SCL inputs suppress noise spikes less than 50ns.

SINK

≤ 6mA.

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Maxim Integrated │

3

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Typical Operating Characteristics

(T

A

= +25°C, unless otherwise noted.)

STANDBY CURRENT vs. TEMPERATURE

1.4

1.2

1.0

0.8

2.0

1.8

1.6

V+ = +2.5V

V+ = +3.3V

f

SCL

= 0kHz

V+ = +5.0V

0.6

0.4

0.2

0

-40

V+ = +1.71V

-25 -10 5 20 35 50 65 80 95 110 125

TEMPERATURE ( °C)

60

50

SUPPLY CURRENT vs. TEMPERATURE

f

SCL

= 400kHz

V+ = +5.0V

40

30

V+ = +3.3V

20

V+ = +2.5V

10

V+ = +1.71V

0

-40 -25 -10 5 20 35 50 65 80 95 110 125

TEMPERATURE ( °C)

OUTPUT VOLTAGE LOW vs. TEMPERATURE

0.40

0.35

0.30

0.25

0.20

0.15

I

V+ = +3.3V

SINK

= 15mA

I

V+ = +5.0V

SINK

= 20mA

0.10

0.05

I

V+ = +1.71V

SINK

= 5mA

I

V+ = +2.5V

SINK

= 10mA

0

-40 -25 -10 5 20 35 50 65 80 95 110 125

TEMPERATURE (

°

C)

6

5

4

3

OUTPUT VOLTAGE HIGH vs. TEMPERATURE

I

V+ = +5.0V

SOURCE

= 10mA

I

V+ = +3.3V

SOURCE

= 5mA

2

1

I

V+ = +1.71V

SOURCE

= 2mA

I

V+ = +2.5V

SOURCE

= 5mA

0

-40 -25 -10 5 20 35 50 65 80 95 110 125

TEMPERATURE (

°

C)

Pin Description

PIN

QSOP TQFN

NAME FUNCTION

1, 3 15, 1 AD0, AD2

Address Inputs. Select device slave address with AD0 and AD2. Connect AD0 and AD2 to either GND, V+, SCL, or SDA to give four logic combinations (see Table 2).

2 16 RST Reset Input. Active Low. Drive RST low to clear the 2-wire interface.

4, 5, 11, 12, 2, 3, 9, 10 O0, O1, O6, O7 Push-Pull Output Ports

6, 7, 9, 10 4, 5, 7, 8

8 6

I2–I5

GND

Input Ports. I2 to I5 are CMOS-logic inputs protected to +6V.

Ground

13

14

15

16

11

12

13

14

EP

INT

SCL

SDA

V+

EP

Interrupt Output, Active Low. INT is an open-drain output.

I

2

C-Compatible Serial-Clock Input

I

2

C-Compatible Serial-Data I/O

Positive Supply Voltage. Bypass V+ to GND with a ceramic capacitor of at least 0.047µF.

Exposed Pad. Connect exposed pad to GND.

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Maxim Integrated │

4

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Detailed Description

MAX7319–MAX7329 Family Comparison

The MAX7319–MAX7323 family consists of five pin- compatible, eight-port expanders. Each version is

MAX7329 are industry-standard parts.

optimized for different applications. The MAX7328 and

The MAX7324–MAX7327 family consists of four pin- compatible, 16-port expanders that integrate the func-tions of the MAX7320 and one of either MAX7319,

MAX7321, MAX7322, or MAX7323.

Functional Overview

The MAX7322 is a general-purpose port expander operating from +1.71V to +5.5V supply that provides four push-pull output ports with 20mA sink, 10mA source drive capability, and four input ports that are overvoltage protected to +6V independent of supply voltage. The

MAX7322 is rated to sink a total of 100mA and source a total of 50mA from all four combined outputs.

The MAX7322 is set to one of 16 I

2

C slave addresses

(0x60 to 0x6F) using address inputs AD2 and AD0, and is accessed over an I

2

C serial interface up to 400kHz.

The RST input clears the serial interface in case of a bus lockup, terminating any serial transaction to or from the MAX7322.

Table 1. MAX7319MAX7329 Family Comparison

PART

I

2

C

SLAVE

ADDRESS

INPUTS

INPUT

INTERRUPT

MASK

OPEN-

DRAIN

OUTPUTS

PUSH-

PULL

OUTPUTS

8-PORT EXPANDERS

I

2

C DATA

WRITE

I

2

C DATA

READ

MAX7319 110xxxx 8 Yes — —

<I7–I0

Interrupt mask>

APPLICATION

<I7–I0 port inputs>

<I7–I0

Transition flags>

Input-only versions:

8 input ports with programmable latching transition detection interrupt and selectable pullups.

Offers maximum versatility for automatic input monitoring. An interrupt mask selects which inputs cause an interrupt on transitions, and transition flags identify which inputs have changed (even momentarily) since the ports were last read.

MAX7320 101xxxx — — — 8

<O7–O0

Port outputs>

<O7-O0 port inputs>

Output-only versions:

8 push-pull outputs with selectable power-up default levels.

Push-pull outputs offer faster rise time than opendrain outputs, and require no pullup resistors.

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MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Table 1. MAX7319MAX7329 Family Comparison (continued)

PART

I

2

C

SLAVE

ADDRESS

INPUTS

INPUT

INTERRUPT

MASK

OPEN-

DRAIN

OUTPUTS

PUSH-

PULL

OUTPUTS

I

2

C DATA

WRITE

I

2

C DATA

READ

MAX7321 110xxxx Up to 8 — Up to 8 —

<P7–P0

Port outputs>

APPLICATION

<P7–P0 port inputs>

<P7–P0

Transition flags>

I/O versions:

8 open-drain I/O ports with latching transition detection interrupt and selectable pullups.

Open-drain outputs can level shift the logic-high state to a higher or lower voltage than V+ using external pullup resistors.

Any port can be used as an input by setting the opendrain output to logic-high.

Transition flags identify which inputs have changed

(even momentarily) since the ports were last read.

MAX7322

MAX7323

MAX7328

MAX7329

110xxxx 4

110xxxx Up to 4

0100xxx

0111xxx

Up to 8

Yes

Up to 4

Up to 8

4

4

<O7, O6 outputs,

I5–I2

Interrupt mask, O1,

O0 outputs>

<port outputs>

<P7–P0

Port outputs>

<O7, O6,

I5–I2, O1,

O0 port inputs>

<0, 0, I5–I2

Transition flags, 0, 0>

<O7, O6,

P5–P2, O1,

O0 port inputs>

<0, 0, P5–

P2

Transition flags, 0, 0>

<P7–P0 port inputs>

4 input-only, 4 output-only versions:

4 input ports with programmable latching transition detection interrupt and selectable pullups;

4 push-pull outputs with selectable power-up default levels.

4 I/O, 4 output-only versions:

4 open-drain I/O ports with latching transition detection interrupt and selectable pullups.

4 push-pull outputs with selectable power-up default levels.

8 open-drain I/O ports with nonlatching transition detection interrupt and pullups on all ports.

All ports power up as inputs

(or logic-high outputs).

Any port can be used as an input by setting the opendrain output to logic-high.

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6

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Table 1. MAX7319MAX7329 Family Comparison (continued)

PART

I

2

C

SLAVE

ADDRESS

INPUTS

INPUT

INTERRUPT

MASK

OPEN-

DRAIN

OUTPUTS

PUSH-

PULL

OUTPUTS

I

2

C DATA

WRITE

I

2

C DATA

READ

16-PORT EXPANDERS

MAX7324 8 Yes — 8 — —

MAX7325

MAX7326

MAX7327

101xxxx

And

110xxxx

Up to 8

4

Up to 4

Yes

Up to 8

Up to 4

8

12

12

APPLICATION

Software equivalent to a

MAX7320 plus a MAX7319.

Software equivalent to a

MAX7320 plus a MAX7321.

Software equivalent to a

MAX7320 plus a MAX7322.

Software equivalent to a

MAX7320 plus a MAX7323.

When the MAX7322 is read through the serial interface the actual logic levels at the ports are read back.

The four input ports offer latching transition detection functionality. All input ports are continuously monitored for changes. An input change sets 1 of 4 flag bits that identify the changed input(s). All flags are cleared upon a subsequent read or write transaction to the MAX7322.

A latching interrupt output, INT, is programmed to flag input data changes on the four input ports through an interrupt mask register. By default, data changes on any input port force INT to a logic low. The interrupt output INT and all transition flags are deasserted when the MAX7322 is next accessed through the serial interface.

Internal pullup resistors to V+ are selected by the address select inputs, AD0 and AD2. Pullups are enabled on the input ports in groups of two (see Table 2).

Output port power-up logic states are selected by the address select inputs AD0 and AD2. Ports default

(see Table 2).

to logic-high or logic-low on power-up in groups of two

Initial Power-Up

On power-up, the transition detection logic is reset, and

INT is deasserted. The interrupt mask register is set to

0x3C, enabling the interrupt output for transitions on all four input ports. The transition flags are cleared to indicate no data changes. The power-up default state of the four push-pull outputs are set according to the I

2

C slave address selection inputs, AD0 and AD2 (Table 2).

Power-On Reset (POR)

The MAX7322 contains an integral POR circuit that ensures all registers are reset to a known state on power-up. When V+ rises above V

POR

(1.6V max), the

POR circuit releases the registers and 2-wire interface for normal operation. When V+ drops to less than V defaults (Table 2).

POR

, the MAX7322 resets all register contents to the POR

RST Input

The active-low RST input operates as a reset that voids any current I

2

C transaction involving the MAX7322, reset action does not clear the interrupt output (INT).

forcing the MAX7322 into the I

2

C STOP condition. The

Standby Mode

When the serial interface is idle, the MAX7322 automatically enters standby mode, drawing minimal supply current.

Slave Address and Input Pullup

Selection/Default Logic State

Address inputs AD0 and AD2 determine the MAX7322 slave address, select which inputs have pullup resistors and set the default logic state for outputs. Pullups are enabled on the input ports in groups of two (see Table 2).

The MAX7319, MAX7321, MAX7322, and MAX7323 use a different range of slave addresses (110xxxx) than the

MAX7320 (101xxxx).

The MAX7322 slave address is determined on each I

2

C transmission, regardless of whether the transmission is actually addressing the MAX7322. The MAX7322 distinguishes whether address inputs AD2 and AD0 are connected to SDA or SCL instead of fixed logic levels

V+ or GND during this transmission. This means that the

MAX7322 slave address can be configured dynamically in the application without cycling the device supply.

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MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

On initial power-up, the MAX7322 cannot decode the address inputs AD2 and AD0 fully until the first I

2

C transmission. AD0 and AD2 initially appear to be connected to V+ or GND. This is important because the address selection determines the power-up logic state, and whether pullups are enabled. However, at power-up, the I

2

C SDA and SCL bus interface lines are high impedance at the pins of every device (master or slave) connected to the bus, including the MAX7322. This is guaranteed as part of the I

2

C specification. Therefore, address inputs AD2 and AD0 that are connected to

SDA or SCL normally appear at power-up to be connected to V+. The port selection logic uses AD0 to select whether pullups are enabled for ports I2 and I3, and to set the initial logic state for ports O0 and O1. AD2 selects whether pullups are enabled for ports I4 and I5 and sets the internal logic state for ports O6 and O7. The rule is that a logic-high, SDA, or SCL connection selects the pullups and sets the default logic state high. A logic- low deselects the pullups and sets the default logic state low (Table 2). This means that the port configuration is correct on power-up for a standard I

2

C configuration, where SDA or SCL are pulled up to V+ by the external I

2

C pullup resistors.

There are circumstances where the assumption that

SDA = SCL = V+ on power-up is not true—for example, in applications in which there is legitimate bus activity during power-up. Also, if SDA and SCL are terminated with pullup resistors to a different supply voltage than the MAX7322’s supply voltage, and if that pullup supply rises later than the MAX7322’s supply, then SDA or

SCL may appear at power-up to be connected to GND.

In such applications, use the four address combina- tions that are selected by connecting address inputs

AD2 and AD0 to V+ or GND (shown in bold in Table 2).

These selections are guaranteed to be correct at power-up, independent of SDA and SCL behavior. If one of the other 12 address combinations is used, an unexpected combination of pullups might be asserted until the first I

2

C transmission (to any device, not necessarily the MAX7322) is put on the bus, and an unexpect- ed combination of ports may initialize as logic-low outputs instead of inputs or logic-high outputs.

Port Inputs

Port inputs switch at CMOS logic levels as determined by the expander’s supply voltage, and are overvoltage tolerant to +6V, independent of the expander’s supply voltage.

Port Input Transition Detection

All four input ports are monitored for changes since the expander was last accessed through the serial interface. The state of the I/O ports is stored in an internal “snapshot” register for transition monitoring.

Table 2. MAX7322 Address Map

PIN

CONNECTION

AD2

SCL

SCL

SCL

SCL

SDA

SDA

SDA

SDA

GND

GND

GND

GND

V+

V+

V+

V+

DEVICE ADDRESS OUTPUTS POWER—UP DEFAULT

40kΩ INPUT PULLUPS

ENABLED

SDA

GND

V+

SCL

SDA

SCL

SDA

GND

V+

SCL

AD0 A6 A5 A4 A3 A2 A1 A0 O7 O6 I5 I4 I3 I2 O1 O0 O7 O6 I5 I4 I3 I2 O1 O0

GND 1 1 0 0 0 0 0 1 1 0 0 Y Y — —

V+

SCL

SDA

GND

V+

1

1

1

1

1

1

1

1

1

1

0

0

0

0

0

0

0

0

0

0

0

0

0

1

1

0

1

1

0

0

1

0

1

0

1

1

1

1

1

1

1

1

1

1

1

1

1

1

0

1

1

1

1

0

1

Y Y Y Y

Y Y Y Y

Y Y Y Y

Y Y — —

Y Y Y Y

1

1

1

1

1

1

1

1

1

1

0

0

0

0

0

1

1

1

0

0

0

0

0

1

1

0

0

1

1

1

0

1

0

0

1

0

0

0

1

1

0

0

0

1

1

Inputs

0

1

1

1

1

0

1

1

1

1

Y Y Y Y

Y Y Y Y

— — — —

— — Y Y

— — Y Y

1

1

1

1

1

1

1

1

1

1

0

0

0

0

0

1

1

1

1

1

0

1

1

1

1

1

0

0

1

1

1

0

1

0

1

0

1

1

1

1

0

1

1

1

1

1

0

1

1

1

1

0

1

1

1

— — Y Y

Y Y — —

Y Y Y Y

Y Y Y Y

Y Y Y Y www.maximintegrated.com

Maxim Integrated │

8

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

The snapshot is continuously compared with the actual input conditions, and if a change is detected for any port input, then an internal transition flag is set for that port, and INT is asserted to signal a state change. The four port inputs are sampled (internally latched into the snapshot register) and the old transition flags cleared during the I

2

C acknowledge of every MAX7322 read and write access. The previous port transition flags are read through the serial interface as the second byte of a 2-byte read sequence.

A long read sequence (more than 2 bytes) can be used to poll the expander continuously without the overhead of resending the slave address. If more than 2 bytes are read from the expander, the expander repeatedly returns the input port data alternating with the transition flags. The inputs are repeatedly resampled and the transition flags repeatedly reset for each pair of bytes read. All changes that occur during a long read sequence are detected and reported.

The MAX7322 includes a 4-bit interrupt mask register that selects which inputs generate an interrupt upon change. Each input’s transition flag is set when its input changes, independent of the interrupt mask register inputs and the transition flags can be polled periodically to detect less-critical events.

settings. The interrupt mask register allows the processor to be interrupted for critical events, while the

The INT output is not reasserted during a read sequence to avoid recursive reentry into an interrupt service routine. Instead, if a data change occurs that would normally cause the INT output to be set, the INT assertion is delayed until the STOP condition. INT is not reasserted upon a STOP condition if the changed input data is read before the STOP occurs. The INT logic ensures that unnecessary interrupts are not asserted, yet data changes are detected and reported no matter when the change occurs.

Transition Detection Masks

The transition detection logic incorporates a change flag and an interrupt mask bit for each of the four input ports. The four change flags can be read through the serial interface, and the 4-bit interrupt mask is set through the serial interface.

Each port’s change flag is set when that port’s input changes, and the change flag remains set even if the input returns to its original state. The port’s interrupt mask determines whether a change on that input port generates an interrupt. Enable interrupts for high- priority inputs using the interrupt mask. The interrupt allows the system to respond quickly to changes on these inputs. Poll the MAX7322 periodically to monitor less- important inputs. The change flags indicate whether a permanent or transient change has occurred on any input since the MAX7322 was last accessed.

Port Outputs

Write one byte to the MAX7322 to set the output port levels for the four push-pull outputs, and the interrupt mask for the four inputs simultaneously.

Serial Interface

Serial Addressing

The MAX7322 operates as a slave that sends and receives data through an I

2

C interface. The interface uses a serial-data line (SDA) and a serial-clock line (SCL) to achieve bidirectional communication between master(s) and slave(s). The master initiates all data transfers to and from the MAX7322 and generates the SCL clock that synchronizes the data transfer (Figure 1).

SDA operates as both an input and an open-drain output.

A pullup resistor, typically 4.7kΩ, is required on SDA.

SCL operates only as an input. A pullup resistor, typically

4.7kΩ, is required on SCL if there are multiple masters

SDA t

LOW t

SU,DAT t

HIGH

SCL t

HD,STA t

R t

F

START CONDITION

Figure 1. 2-Wire Serial Interface Timing Details

t

HD,DAT t

SU,STA t

HD,STA

REPEATED START CONDITION t

SU,STO t

BUF

STOP

CONDITION

START

CONDITION www.maximintegrated.com

Maxim Integrated │

9

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs on the 2-wire interface, or if the master in a single-master system has an open-drain SCL output.

Each transmission consists of a START condition sent by a master, followed by the MAX7322’s 7-bit slave address plus R/W bit, one or more data bytes, and finally a STOP condition (Figure 2).

Start and Stop Conditions

Both SCL and SDA remain high when the interface is not busy. A master signals the beginning of a transmission with a START (S) condition by transitioning SDA from high to low while SCL is high. When the master has finished communicating with the slave, the master issues a STOP

(P) condition by transitioning SDA from low to high while

SCL is high. The bus is then free for another transmission

(Figure 2).

Bit Transfer

One data bit is transferred during each clock pulse.

The data on SDA must remain stable while SCL is high

(Figure 3).

Acknowledge

The acknowledge bit is a clocked 9th bit the recipient uses to acknowledge receipt of each byte of data

(Figure 4).Each byte transferred effectively requires

9 bits. The master generates the 9th clock pulse, and the recipient pulls down SDA during the acknowledge clock pulse, such that the SDA line is stable low during the high period of the clock pulse. When the master is transmitting to the MAX7322, the MAX7322 generates the acknowledge bit because the device is the recipient. When the MAX7322 is transmitting to the master, the master generates the acknowledge bit because the master is the recipient.

SDA

SCL

DATA LINE STABLE;

DATA VALID

CHANGE OF DATA

ALLOWED

Figure 3. Bit Transfer

SDA

SCL

S

START

CONDITION

Figure 2. Start and Stop Conditions

P

STOP

CONDITION

START

CONDITION

SCL

SDA BY

TRANSMITTER

SDA BY

RECEIVER

S

Figure 4. Acknowledge

1 2

CLOCK PULSE

FOR ACKNOWLEDGMENT

8 9 www.maximintegrated.com

Maxim Integrated │

10

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Slave Address

The MAX7322 has a 7-bit-long slave address (Figure 5).

The eighth bit following the 7-bit slave address is the R/W bit. It is low for a write command, and high for a read command.

The first (A6), second (A5), and third (A4) bits of the

MAX7322 slave address are always 1, 1, and 0. Connect

AD2 and AD0 to GND, V+, SDA, or SCL to select slave address bits A3, A2, A1, and A0. The MAX7322 has 16 possible slave addresses (Table 2), allowing up to 16

MAX7322 devices on an I

2

C bus.

Accessing the MAX7322

The MAX7322 is accessed through an I

2

C interface.

The transition flags are cleared, and INT is deasserted each time the device acknowledges the I

2

C slave address.

A single-byte read from the MAX7322 returns the status of the four input ports and the four output ports (read back as inputs).

A 2-byte read returns the status of the four input ports and the four output ports (as for a single-byte read), followed by the transition flags for the four input ports.

A

multibyte read (more than 2 bytes before the I

2

C

STOP bit) repeatedly returns the port data, alternating with the transition flags. As the data is resampled for each transmission, and the transition flags are reset each time, a multibyte read continuously returns the current data and identifies any changing ports.

If a port data change occurs during the read sequence,

INT is reasserted after the I

2

C STOP bit. The MAX7322 does not generate another interrupt during a single-byte or multibyte read.

Port data is sampled during the preceding I address in the case of a single-byte or 2-byte read).

2

C acknowledge bit (the acknowledge bit for the I

2

C slave

A single-byte write to the MAX7322 sets the logic state of the four output ports and the 4-bit interrupt mask resistor, and clears both the internal transition flags and the INT output when the device acknowledges the slave address byte.

A

multibyte write to the MAX7322 repeatedly sets the logic state of the four output ports and the 4-bit interrupt mask register.

SDA

1

MSB

SCL

Figure 5. Slave Address

1

0

A3 A2 A1 A0

LSB

R/W

ACK www.maximintegrated.com

Maxim Integrated │

11

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Reading from the MAX7322

A read from the MAX7322 starts with the master transmitting the MAX7322’s slave address with the R/W bit set high. The MAX7322 acknowledges the slave address, and samples the ports during the acknowledge bit. INT deasserts during the slave address acknowledge.

Typically, the master reads one or two bytes from the MAX7322, each byte being acknowledged by the master upon reception with the exception of the last byte.

When the master reads one byte from the MAX7322 and subsequently issues a STOP condition (Figure 6), the MAX7322 transmits the current port data, clears the change flags, and restarts the transition detection.

INT deasserts during the slave address acknowledge.

The new snapshot data is the current input port data transmitted to the master, so any input port changes that occur during the transmission are detected. INT remains high until the STOP condition.

The master can read two bytes from the MAX7322 and then issue a STOP condition (Figure 7). In this case, the

MAX7322 transmits the current port data, followed by the change flags. The change flags are then cleared, and transition detection restarts. INT deasserts during the slave address acknowledge. The new snapshot

S = START CONDITION

P = STOP CONDITION

SHADED = SLAVE TRANSMISSION

N = NOT ACKNOWLEDGE

S 1 1 0

MAX7322 SLAVE ADDRESS

1

R/W

SCL

O7 O6 I5

PORTS

I4 I3 I2 O1 O0

ACKNOWLEDGE

FROM MAX7322

A D7 D6 D5

PORT SNAPSHOT

D4 D3 D2 D1 D0

PORT SNAPSHOT

N P t

PH

PORTS t

IV

INT OUTPUT t

IR t

PSU

INT REMAINS HIGH UNTIL STOP CONDITION t

IP

Figure 6. Reading from the MAX7322 (1 Data Byte)

S = START CONDITION

P = STOP CONDITION

SHADED = SLAVE TRANSMISSION

N = NOT ACKNOWLEDGE

O7 O6 I5

PORT INPUTS

I4 I3 I2 I1 O0 0 0

INTERRUPT FLAGS

F5 F4 F3 F2 0 0

ACKNOWLEDGE

FROM MAX7322

S 1 1 0 MAX7322 SLAVE ADDRESS 1

R/W

A D7 D6 D5

PORT SNAPSHOT

D4 D3 D2 D1 D0

PORT SNAPSHOT

A D7 D6 D5 D4 D3 D2 D1 D0

PORT SNAPSHOT

N P

SCL t

PH

PORTS t

IV

INT OUTPUT t

IR t

PSU

INT REMAINS HIGH UNTIL STOP CONDITION t

IP

Figure 7. Reading from the MAX7322 (2 Data Bytes)

www.maximintegrated.com

Maxim Integrated │

12

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs data is the current port data transmitted to the master, so any input port changes occurring during the

STOP condition.

transmission are detected. INT remains high until the

Writing to the MAX7322

A write to the MAX7322 starts with the master transmitting the MAX7322’s slave address with the R/W bit set low. The MAX7322 acknowledges the slave address, and samples the ports (takes a snapshot) during acknowledge. INT deasserts during the slave acknowledge. The master proceeds to transmit 1 or more bytes of data. The MAX7322 acknowledges these subsequent bytes of data and updates the four output ports and the 4-bit interrupt mask register with each new byte until the master issues a STOP condition (Figure 8).

Applications Information

Port Input and I

2

C Interface Level

Translation from Higher or Lower

Logic Voltages

The MAX7322’s SDA, SCL, AD0, AD2, input RST, INT, and input ports I2–I5 are overvoltage protected to +6V independent of V+. This allows the MAX7322 to operate from a lower supply voltage, such as +3.3V, while the I

2

C interface and/or some of the four input ports are driven from a higher logic level, such as +5V.

The MAX7322 can operate from a higher supply voltage, such as +3V, while the I

2

C interface and/or some of the four input ports I2–I5 are driven from a lower logic level, such as +2.5V. Apply a minimum voltage of 0.7 x V+ to assert a logic-high on any input. For example, a MAX7322 operating from a +5V supply may not recognize a +3.3V nominal logic-high. One solution for input-level translation is to drive the MAX7322 inputs from open-drain outputs.

Use a pullup resistor to V+ or a higher supply to ensure a high logic voltage of greater than 0.7 x V+.

SCL

SDA

S

1 2 3 4 5 6 7 8

SLAVE ADDRESS

0 A

START CONDITION

INTERNAL WRITE

TO PORT

DATA OUT

FROM PORT

S = START CONDITION

P = STOP CONDITION

SHADED = SLAVE TRANSMISSION

N = NOT ACKNOWLEDGE

DATA TO INTERRUPT MASK

R/W ACKNOWLEDGE

FROM SLAVE

DATA 1 t

PV

DATA TO INTERRUPT MASK

A

ACKNOWLEDGE

FROM SLAVE

DATA 2

DATA 1 VALID t

PV

A

ACKNOWLEDGE

FROM SLAVE

DATA 2 VALID

Figure 8. Writing to the MAX7322

www.maximintegrated.com

Maxim Integrated │

13

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Port Structures

Each of the four output ports O0, O1, O6, and O7 has protection diodes to V+ and to GND (Figure 9). When a port output is driven to a voltage lower than GND, the appropriate protection diode clamps the output to a diode drop above V+ or below GND. When the MAX7322 is powered down (V+ = 0), each output port appears as a diode clamp to GND (Figure 9).

Each of the four input ports I2–I5 has a protection diode to

GND (Figure 10). When a port input is driven to a voltage lower than GND, the protection diode will clamp the input to a diode drop below GND.

Each of the four inputs ports I2–I5 also has a 40kΩ (typ) pullup resistor that can be enabled or disabled. When a port is driven to a voltage higher than V+, the body diode of the pullup enable switch conducts and the 40kΩ pullup resistor is enabled. When the MAX7322 is powered down (V+ = 0), each input port appears as a 40kΩ pullup resistor in series with a diode connected to zero.

Input ports are protected to +6V under any of these circumstances (Figure 10).

Driving LED Loads

When driving LEDs from one of the four output ports

O0, O1, O6, or O7, a resistor must be connected in series with the LED to limit the LED current to no more than

20mA. Connect the LED cathode to the MAX7322 port, and the LED anode to V+ through the series current- limiting resistor, R

LED

. Set the port output low to light the

LED. Choose the resistor value according to the following formula:

R

LED

= (V

SUPPLY

- V

LED

- V

OL

) / I

LED where:

R

LED

is the resistance of the resistor in series with the

LED (Ω).

V

SUPPLY

LED (V).

is the supply voltage used to drive the

V

LED

is the forward voltage of the LED (V).

V

OL

is the output low voltage of the MAX7322 when sinking I

LED

(V).

I

LED

is the desired operating current of the LED (A).

For example, to operate a 2.2V red LED at 10mA from a

+5V supply:

R

LED

= (5 - 2.2 - 0.07) / 0.010 = 270Ω

Driving Load Currents Higher than 20mA

The MAX7322 can be used to drive loads, such as relays, that draw more than 20mA by paralleling outputs. Use at least one output per 20mA of load current; for example, a 5V 330mW relay draws 66mA, and therefore, requires all four paralleled outputs. Any combination of outputs can be used as part of a load- sharing design, because any combination of ports can be set or cleared at the same time by writing to the

MAX7322. Do not exceed a total sink current of 100mA for the device.

The MAX7322 must be protected from the negative voltage transient generated when switching off inductive loads (such as relays), by connecting a reverse- biased diode across the inductive load. Choose the peak current for the diode to be greater than the inductive load’s operating current.

Power-Supply Considerations

The MAX7322 operates with a supply voltage of

+1.71V to +5.5V over the -40°C to +125°C temperature range. Bypass the supply to GND with a ceramic capacitor of at least 0.047°F as close to the device as possible. For the TQFN version, additionally connect the exposed pad to GND.

MAX7322

OUTPUT

PULLUP

ENABLE

V+ V+

V+ V+

PORTS

O0, O1, O6, O7

Figure 9. MAX7322 Push-Pull Output Port Structure

INPUT

40kΩ

MAX7322

Figure 10. MAX7322 Input Port Structure

PORTS

I2–I5 www.maximintegrated.com

Maxim Integrated │

14

MAX7322

Functional Diagram

AD0

AD2

SCL

SDA

INPUT

FILTER

I

2

C

CONTROL

I/O

PORTS

I2

I3

O0

O1

I4

I5

O6

O7

RST

POWER-

ON RESET

MAX7322

Pin Configurations (continued)

TOP VIEW

AD0

RST

AD2

I3

GND

O0

O1

I2

5

6

7

8

1

2

3

4

+

MAX7322

QSOP

16 V+

15

14

SDA

SCL

11

10

13

12

9

INT

O7

O6

I5

I4

INT

I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Typical Application Circuit

µ

C

SCL

SDA

RST

INT

3.3V

0.047F

V+

SCL

SDA

RST

INT

AD0

AD2

MAX7322

GND

O7

O6

O1

O0

I3

I2

I5

I4

OUTPUT

OUTPUT

INPUT

INPUT

INPUT

INPUT

OUTPUT

OUTPUT

Chip Information

PROCESS: BiCMOS

Package Information

For the latest package outline information and land patterns

(footprints), go to

www.maximintegrated.com/packages

. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.

PACKAGE

TYPE

16 QSOP

16 TQFN-EP

PACKAGE

CODE

E16+4

T1633+4

OUTLINE

NO.

21-0055

21-0136

LAND PATTERN

NO.

90-0167

90-0031

www.maximintegrated.com

Maxim Integrated │

15

MAX7322 I

2

C Port Expander with

4 Push-Pull Outputs and 4 Inputs

Revision History

REVISION

NUMBER

1

REVISION

DATE

7/07

2 5/14

DESCRIPTION

No /V OPNs; removed automotive reference from Applications section; updated

Packaging Information

PAGES

CHANGED

1–17

1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.

Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.

Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.

© 2014 Maxim Integrated Products, Inc. │ 16

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