Remote Antenna, Current-Sense and LDO/Switches MAX16946
EVALUATION KIT AVAILABLE
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
General Description
The MAX16946/MAX16947 high-voltage, high-side, current-sense LDO/switches feature internal current limiting
to prevent system damage due to fault conditions. The
MAX16946 provides a fixed regulated 8.5V output voltage or an adjustable 3.3V to 15V output voltage. The
MAX16946 can also be configured as a switch, while
the MAX16947 is only available as a switch. The input
voltage range for both devices extends from 4.5V to 18V
(45V tolerant), making the devices ideal for providing
phantom power to remote radio-frequency low-noise
amplifiers (LNAs) in automotive applications.
The devices monitor the load current and provide an
analog output voltage proportional to the sensed load
current. Accurate internal current limit protects the input
supply against both overload and short-circuit conditions. Two open-drain fault indicator outputs indicate to
the microprocessor when a short circuit, an open-load
condition, or a short-to-battery condition exists. An overtemperature shutdown is also indicated by means of the
current-sense amplifier’s output voltage.
A fault-blanking feature allows the devices to ignore
momentary faults such as those caused by the charging of capacitive loads during hot-swapping, preventing
false alarms to the system. The devices feature shortto-battery protection to latch off the internal LDO/pass
switch during a short-to-battery event. During a thermal
overload, the devices reduce power dissipation by going
into thermal shutdown. They include an active-low, highvoltage-compatible shutdown input to place them in lowpower shutdown mode.
The MAX16946 is available in thermally enhanced, 16-pin
TQFN-EP and QSOP-EP packages. The MAX16947 is available in a 16-pin QSOP package. Both devices operate over
the -40NC to +105NC temperature range.
Features
S Switch Phantom Power-On/Off Under µC Control
S Precision Adjustable Current Limit
300mA (max), TA = +105NC
500mA (max), TA = +85NC (MAX16946 in SW
Mode Only)
S Regulated Output Voltage (MAX16946)—8.5V
Fixed or Adjustable Between 3.3V and 15V
S Current Measurement Analog Voltage Output
S Detect Open-Load and Short-Circuit Conditions
S Provide Open-Drain Fault Signals (SC and OL)
S Overcurrent Blanking During Startup
S Thermal Shutdown
S AEC-Q100 Qualified
S -40NC to +105NC Operating Temperature Range
Applications
Remote LNA Phantom Power
Automotive Safety and Infotainment
Automotive Remote Module Power
Functional Diagram
IN
SENS
OUT
FB
(GND)
HIGH
VOLTAGE
CHARGE PUMP AND GATE DRIVER
AV =
26V/V
CURRENT
LIMIT COMP
COMP
LIM
AOUT
SC COMP
BUFFER
SC
SHORT-TO
BATTERY
COMP
SC REF
Ordering Information
PART
PIN-PACKAGE
OUTPUT
MAX16946GEE/V+
16 QSOP-EP*
Switch or LDO
MAX16946GTE/V+
16 TQFN-EP*
Switch or LDO
MAX16947GEE/V+**
16 QSOP
Switch
Note: All devices are specified over the -40°C to +105°C
operating temperature range.
/V Denotes an automotive qualified part.
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
**Future product—contact factory for availability.
REVERSECURRENT
COMP
LOGIC
TIMER
REVERSE
OSCILLATOR
CURRENT REF
OL COMP
MAX16946
MAX16947
SHDN
REG
GND
OL
OLT
5V
REGULATOR
ULVO +
REFUV
OVLO
BANDGAP
AND
THERMAL
SHUTDOWN
BUFFER
REF
IN
REF
() MAX16947
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-5575; Rev 3; 6/14
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ABSOLUTE MAXIMUM RATINGS
SC, OL, REG to GND............................................-0.3V to +6.0V
OLT, LIM, FB, AOUT, REF,
COMP to GND......................................-0.3V to (VREG + 0.3V)
IN, SENS, SHDN to GND.......................................-0.3V to +28V
IN, SENS, SHDN to GND (< 1s).............................-0.3V to +45V
OUT to GND...........................................................-0.3V to +20V
IN to SENS.............................................................-0.3V to +0.3V
Continuous Power Dissipation (TA = +70NC)
QSOP (derate 9.5mW/NC above +70NC)......................761mW
QSOP-EP (derate 22.7mW/NC above +70NC).............1818mW
TQFN-EP (derate 25mW/NC above +70NC)......................2000mW
Junction-to-Ambient Thermal Resistance (BJA) (Note 1)
QSOP..........................................................................105NC/W
QSOP-EP.......................................................................44NC/W
TQFN-EP.......................................................................40NC/W
Junction-to-Case Thermal Resistance (BJC) (Note 1)
QSOP ...........................................................................37NC/W
QSOP-EP.........................................................................6NC/W
TQFN-EP.........................................................................6NC/W
Operating Temperature Range......................... -40NC to +105NC
Junction Temperature....................................... -40NC to +150NC
Storage Temperature Range............................. -65NC to +150NC
Lead Temperature (soldering, 10s).................................+300NC
Soldering Temperature (reflow).......................................+260NC
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
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
(VIN = 12V, VGND = 0V, TA = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
18
V
28
V
POWER SWITCH/LDO
Full performance
4.5
IN Operating Supply Range
VIN
Output switched off (Note 2)
IN Supply Current
ICC
V SHDN > 2.4V, TA = +25NC
IN Shutdown Supply Current
ISD
V SHDN = VGND, TA = +25NC, VIN = 12V
Falling VIN
3.5
Rising VIN
3.9
Hysteresis
0.4
Output switched off for < 1s (Note 2)
Undervoltage Lockout
(Rising)
VUVLO
2.1
Measured between SENS and OUT while
sourcing 100mA, FB grounded, SW
operation, TA = +25NC, 4.5V < VIN < 18V
Internal Switch Voltage Drop
Internal Voltage Regulator
Feedback Voltage
2 VSW
VREG
VFB
Measured between SENS and OUT while
sourcing 100mA, FB grounded, SW
operation, TA = +105NC, 4.5V < VIN < 18V
(Note 2)
0.2
IREG = 0mA, TA = +25NC
MAX16946 only,
LDO mode with
FB connected to
external resistive
divider
45
V
2.6
mA
7
FA
V
0.20
V
0.25
V
5
V
IOUT = 5mA to
150mA, 4.5V P VIN P
18V
0.97
1
1.03
V
IOUT = 2mA to
200mA, 4.5V < VIN
P 18V
0.95
1
1.05
V
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 12V, VGND = 0V, TA = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.)
PARAMETER
Feedback Input Bias Current
Fixed 8.5V to LDO Mode
Feedback Threshold
Adjustable Output Voltage
Range
SYMBOL
IFB
VFB_TH
VOUT
CONDITIONS
VFB = 1.0V, LDO mode, TA = +25NC
MIN
TYP
-0.5
VFB = 1.0V, LDO mode, TA = +105NC
MAX
+0.5
0
UNITS
FA
Switching to LDO mode from fixed 8.5V
3.3
4.2
V
LDO mode with external resistive divider,
VIN > VOUT + VDROPOUT (Note 3)
3.3
15
V
VIN - VOUT R 2V, IOUT = 5mA to 100mA,
LDO mode
-2
%
FB Line Regulation
VIN - VOUT R 2V, IOUT = 6mA, LDO mode
20
mV/V
Fixed 8.5V Output Voltage
IOUT = 5mA, LDO mode with internal
resistive divider, 9V P VIN P 18V
FB Load Regulation
VOUT_8.5V
Power-Supply Rejection
Ratio
PSRR
Startup Response Time
tST
8.33
8.5
8.67
V
VIN - VOUT R 2V, f = 100Hz, LDO mode
50
dB
SHDN rising to switch/LDO on, time
needed to charge CCOMP = 0.1FF
10
ms
OUT Pulldown Resistor Value
ROUT_OFF
V SHDN = VGND, TA = +25NC
250
kI
COMP Power-Down Resistor
Value
RCOMP_OFF
V SHDN = VGND, TA = +25NC
120
kI
26.65
V/V
125
mV
0.432
V
CURRENT-SENSE AMPLIFIER
AOUT Gain
Current-Sense Amplifier
Input Voltage Range
AV
VAOUT/(VIN - VSENS), measured with
VIN - VSENS = 20mV and 100mV,
4.5V < VIN < 18V
25.35
VINR
Drop across the shunt resistor, normal
operation
0
AOUT Zero-Current Output
Voltage
VAOUT_ZS
(VIN - VSENS) = 0V, 4.5V < VIN < 18V
0.368
Maximum AOUT Voltage
VAOUT_FS
(VIN - VSENS) = 125mV, if VLIM = VREF
then VAOUT(MAX) = 3V
AOUT Drive Capability
IAOUT
AOUT Leakage Current
IAOUT_LEAK
(VIN - VSENS) = 30mV
V SHDN = VGND, TA = +25NC
SENS Leakage Current
ISENS­_LEAK
V SHDN = VGND, TA = +25NC
26
0.4
3.65
V
1.0
mA
2
FA
2
FA
3.06
V
REFERENCE
REF Output Voltage
REF Undervoltage
REF Output Current
REF Leakage Current
VREF
VREF_UV
4.5V < VIN < 18V
VREF falling
IREF
IREF_LEAK
2.94
3
2.18
2.72
100
V
FA
V SHDN = VGND, TA = +25NC
2
FA
1.7
V
+40
mV
FAILURE DETECTION COMPARATORS
Open-Load Comparator
Input Common-Mode Range
Open-Load Comparator
Offset Voltage
Maxim Integrated
VOLT_CMR
VOLT_OS
(Note 2)
0.4
VOLT = 1.05V
-40
0
3
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 12V, VGND = 0V, TA = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.)
PARAMETER
SYMBOL
OLT Input Bias Current
IOLT
Initial Open-Load Blanking
Time
tOL
Open-Load Glitch Immunity
Current-Limit Comparator
Input Common-Mode Range
MIN
TYP
-0.5
VOLT = 1.05V, TA = +105NC
MAX
+0.5
0
UNITS
FA
A switched open load is blanked for tOL
100
tOL_GLITCH
IOUT < IOL
10
100
Fs
VLIM_CMR
If VLIM is derived from REF then maximum
voltage at LIM is 3V (Note 2)
1.7
3.65
V
VLIM = 2.675V
-80
+80
mV
VLIM = 2.675V, TA = +25NC
-0.5
Current-Limit Comparator
Input Offset Voltage
VLIM_OS
LIM Input Bias Current
ILIM_BIAS
Short-Circuit AOUT Voltage
Threshold
CONDITIONS
VOLT = 1.05V, TA = +25NC
VSC
VLIM = 2.675V, TA = +105NC
ms
0
+0.5
0
Rising VAOUT at which the SC output
asserts low, hysteresis of 40mV,
4.5V < VIN < 18V
1.65
1.7
1.75
FA
V
Short-Circuit Current
Blanking Time
tBLANK
IOUT > ISC
100
ms
Delay Time Before Retry
After Short-Circuit Current
Turn-Off
tRETRY
IOUT > ISC
1100
ms
IN Overvoltage Lockout
Threshold
VOVLO
VIN rising, hysteresis = 0.5V (typ)
19
21
23
V
VOUT_BAT
Short to battery detected when VOUT - VIN
> VOUT_BAT
0
250
500
mV
Reverse-Current Detection
Level
VREV
Power switch on (SW or LDO mode), VREV
= VIN - VSENS, VREV = -9.6mV produces
VAOUT = 150mV, VREV = -5.7mV
produces VAOUT = 250mV
-9.6
-5.7
mV
Reverse-Current Shutdown
Time
tSD_REV
Delay to shut down switch or LDO after
VREV exceeds -7.7mV (typ), TA = +25NC
5
Fs
Feedback Voltage Out of
Range
VFB_ERR
LDO mode
1.28
V
Short-to-BAT Threshold in
Off-State
Reverse-Current Blanking
Time for Short-Circuit Events
tREV_BLANK
Switching on and off into a temporary load
(short-circuit events)
1.12
16
ms
OVERTEMPERATURE PROTECTION
Thermal Shutdown Threshold
TSHDN
+170
NC
Thermal Shutdown
Hysteresis
THYST
15
NC
LOGIC
SC, OL Output-Voltage Low
VOL
SC, OL Open-Drain Leakage
Current
ISC_LEAK,
IOL_LEAK
4 Sinking current = 1mA
SC, OL not asserted, VSC = VOL = 5V,
TA = +25NC
0.4
V
1
FA
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ELECTRICAL CHARACTERISTICS (continued)
(VIN = 12V, VGND = 0V, TA = -40NC to +105NC, unless otherwise noted. Typical values are at TA = TJ = +25NC.)
PARAMETER
SYMBOL
SHDN Input-Voltage High
VSHDN_HI
SHDN Input-Voltage Low
VSHDN_LO
SHDN Input Current
ISHDN
SHDN Off-Time
CONDITIONS
MIN
TYP
MAX
UNITS
2.7
V
0.8
VSHDN > 6V
V
5
tSHDN_OFF
150
FA
256
420
Fs
Note 2: Guaranteed by design and not production tested.
Note 3:VDROPOUT is voltage from VIN to VOUT and includes drop across the sense resistor and internal power FET. Additionally,
VOUT + VDROPOUT < VOVLO(MIN) = 19V.
Typical Operating Characteristics
(VIN = 14V, RSENSE = 0.5ω, TA = +25°C, unless otherwise noted.)
150
125
100
FB = REG
3
IIN (mA)
ISENS (nA)
4
2
OPERATING SUPPLY CURRENT vs. TEMPERATURE
(MAX16946/MAX16947 SWITCH CONFIGURATION)
4
MAX16946 toc03
175
VIN = 12V
3
IIN (mA)
FB = GND
SHDN = 0
MAX16946 toc01
200
OPERATING SUPPLY CURRENT vs. TEMPERATURE
(MAX16946 8.5V LDO CONFIGURATION)
MAX16946 toc02
SENSE LEAKAGE CURRENT
vs. TEMPERATURE
2
75
50
1
1
25
VIN = 4.5V
0
-50
-25
0
25
50
75
100
0
125
0
-50
-25
0
25
50
75
100
125
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
OPERATING SUPPLY CURRENT vs. SUPPLY VOLTAGE
(MAX16964/MAX16947 SWITCH CONFIGURATION)
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
1.50
6
FB = GND
SHDN = 0
VIN = 18V
VIN = 14V
5
1.00
0.75
5
4
3
VIN = 12V
VIN = 4.5V
1
0.25
0
4
6
8
10
12
VIN (V)
Maxim Integrated
14
16
18
4
3
2
2
0.50
FB = GND
SHDN = 0
6
IIN (µA)
IIN (µA)
1.25
7
MAX16946 toc05
1.75
IIN (mA)
7
MAX16946 toc04
2.00
125
MAX16946 toc06
TEMPERATURE (°C)
1
0
0
-50
-25
0
25
50
75
TEMPERATURE (°C)
100
125
4
6
8
10
12
14
16
18
VIN (V)
5
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Typical Operating Characteristics (continued)
(VIN = 14V, RSENSE = 0.5ω, TA = +25°C, unless otherwise noted.)
TA = +25°C
TA = +125°C
TA = -40°C
20 40 60 80 100 120 140 160 180 200
0
TA = -40°C
20 40 60 80 100 120 140 160 180 200
0
20 40 60 80 100 120 140 160 180 200
0
OUTPUT VOLTAGE vs. TEMPERATURE
(MAX16946 8.5V LDO CONFIGURATION)
5.010
VIN = 10V
VOUT = 5V
5.009
VOUT (V)
VOUT (V)
5.007
IOUT = 50mA
8
10
12
14
16
8.45
-50
-25
0
25
50
75
100
125
-50
-25
0
25
50
75
100
TEMPERATURE (°C)
TEMPERATURE (°C)
REF OUTPUT VOLTAGE
vs. TEMPERATURE
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
-20
PSRR (dB)
3.015
3.005
2.995
2.985
VOUT = 3.3V
-30
-40
-40
-50
-60
IOUT = 50mA
2.975
-80
2.965
-90
25
50
75
TEMPERATURE (°C)
100
125
IOUT = 50mA
-50
-60
-70
-80
IOUT = 5mA
IOUT = 5mA
-90
-100
0
VOUT = 8.5V
-20
-30
-70
2.955
0
-10
125
MAX16946 toc15
0
-10
PSRR (dB)
3.025
-25
IOUT = 90mA
SUPPLY VOLTAGE (V)
IREF = 100µA
FB = REG
-50
8.48
8.46
5.004
18
8.49
8.47
MAX16946 toc14
6
MAX16946 toc13
4
IOUT = 50mA
8.50
5.005
100
VIN = 12V
FB = REG
8.51
IOUT = 90mA
5.006
102
8.52
MAX16946 toc11
IOUT = 90mA
MAX16946 toc12
OUTPUT VOLTAGE
vs. TEMPERATURE
104
6 TA = -40°C
DROPOUT VOLTAGE vs. SUPPLY VOLTAGE
(SWITCHED OUTPUT)
106
3.035
TA = +105°C
LOAD CURRENT (mA)
5.008
3.045
MAX16946 toc09
MAX16946 toc08
TA = +105°C
TA = +25°C
LOAD CURRENT (mA)
108
DROPOUT VOLTAGE (mV)
TA = +25°C
340
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
LOAD CURRENT (mA)
110
VREF (V)
340
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE (mV)
MAX16946 toc07
340
320
300
280
260
240
220
200
180
160
140
120
100
80
60
40
20
0
DROPOUT VOLTAGE vs. LOAD CURRENT
(OUTPUT = 8.5V)
DROPOUT VOLTAGE vs. LOAD CURRENT
(OUTPUT = 5V)
MAX16946 toc10
DROPOUT VOLTAGE (mV)
DROPOUT VOLTAGE vs. LOAD CURRENT
(SWITCHED OUTPUT)
-100
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
10k
100k
FREQUENCY (Hz)
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Typical Operating Characteristics (continued)
(VIN = 14V, RSENSE = 0.5ω, TA = +25°C, unless otherwise noted.)
LOAD TRANSIENT RESPONSE
(5V LDO MODE)
LINE TRANSIENT RESPONSE
(5V LDO MODE)
MAX16946 toc16
MAX16946 toc17
VIN
5V/div
IOUT
50mA/div
0A
0V
VOUT
(AC-COUPLED)
200mV/div
VOUT
(AC-COUPLED)
500mV/div
100µs/div
4ms/div
POWER-UP WAVEFORMS
(VOUT = 8.5V, IOUT = 90mA)
POWER-UP WAVEFORMS
(SW MODE, IOUT = 90mA)
MAX16946 toc18
MAX16946 toc19
VIN
5V/div
VIN
5V/div
VOUT
5V/div
VOUT
5V/div
IOUT
100mA/div
IOUT
100mA/div
2ms/div
2ms/div
STARTUP WAVEFORMS
(VOUT = 8.5V, IOUT = 90mA)
STARTUP WAVEFORMS
(SW MODE, IOUT = 90mA)
MAX16946 toc20
MAX16946 toc21
VSHDN
5V/div
VSHDN
5V/div
2ms/div
Maxim Integrated
VOUT
5V/div
VOUT
5V/div
IOUT
100mA/div
IOUT
100mA/div
2ms/div
7
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Typical Operating Characteristics (continued)
(VIN = 14V, RSENSE = 0.5ω, TA = +25°C, unless otherwise noted.)
HIGH-VOLTAGE LINE TRANSIENT RESPONSE
(MAX16947)
MAX16946 toc22
27.00
45V
VIN
20V/div
14V
IOUT
50mA/div
0A
VAOUT
1V/div
0V
100ms/div
VIN - VSENS = 20mV AND 100mV
26.75
26.50
AV (V/V)
VOUT
10V/div
0V
MAX16946 toc23
AOUT GAIN
vs. TEMPERATURE
26.25
26.00
25.75
25.50
25.25
25.00
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
25.95
25.90
FB = GND
350
300
25.85
tBLANK (ms)
GAIN (V/V)
400
MAX16946 toc24
26.00
MAX16946 toc25
OVERCURRENT BLANKING TIME
vs. TEMPERATURE
CURRENT-SENSE AMPLIFIER GAIN
vs. TEMPERATURE
25.80
25.75
250
200
25.70
150
25.65
25.60
-40 -25 -10 5
-50
-25
0
25
50
75
100
OVERCURRENT BLANKING TIME
vs. SUPPLY VOLTAGE
DROPOUT VOLTAGE (VSENS - VOUT) vs. TEMPERATURE
(MAX16946 SWITCH CONFIGURATION)
FB = GND
200
175
MAX16946 toc27
TEMPERATURE (°C)
350
IOUT = 100mA
FB = GND
VSENS - VOUT (mV)
150
300
tBLANK (ms)
125
TEMPERATURE (°C)
MAX16946 toc26
400
100
20 35 50 65 80 95 110
250
200
125
100
75
50
150
25
100
4
6
8
10
12
VIN (V)
8 14
16
18
0
-50
-25
0
25
50
75
100
125
TEMPERATURE (°C)
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Typical Operating Characteristics (continued)
(VIN = 14V, RSENSE = 0.5ω, TA = +25°C, unless otherwise noted.)
OPEN-LOAD FAULT
(VOUT = 8.5V, IOUT = 50mA)
DROPOUT VOLTAGE (VSENS - VOUT) vs. TEMPERATURE
(MAX16946 8.5V LDO CONFIGURATION)
175
IOUT = 100mA
FB = REG
150
VSENS - VOUT (mV)
MAX16946 toc29
MAX16946 toc28
200
VOUT
5V/div
125
100
75
IOUT
50mA/div
50
25
VDL
5V/div
0
-50
-25
0
25
50
75
100
100µs/div
125
TEMPERATURE (°C)
CLEARING OPEN-LOAD FAULT
(VOUT = 8.5V, IOUT = 50mA)
MAX16946 toc30
VSHDN
5V/div
VOUT
5V/div
IOUT
50mA/div
VDL
5V/div
100µs/div
Maxim Integrated
9
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Pin Configurations
TOP VIEW
REF
LIM
OLT
GND
TOP VIEW
12
11
10
9
IN 1
REG 13
8
AOUT
FB 14
7
OL
6
SC
5
COMP
MAX16946
GND 15
OUT 16
EP
1
2
3
4
IN
SENS
SHDN
GND
+
TOP VIEW
+
MAX16946
16 OUT
IN 1
+
16 OUT
SENS 2
15 GND
SHDN 3
14 FB
GND 4
13 REG
GND 4
COMP 5
12 REF
COMP 5
12 REF
SC 6
11 LIM
SC 6
11 LIM
OL 7
10 OLT
AOUT 8
9 GND
15 GND
SENS 2
OL 7
EP
AOUT 8
10 OLT
SHDN 3
MAX16947
14 GND
13 REG
9 GND
QSOP
QSOP
TQFN
Pin Description
PIN
NAME
FUNCTION
MAX16946
MAX16947
1
1
IN
2
2
SENS
Current-Sense Amplifier Input. Connect the sense resistor between SENS and IN.
3
3
SHDN
Active-Low Shutdown Input. Drive SHDN low for more than 360Fs to turn off the device.
Pulsing SHDN low for less than tSHDN_OFF clears the OL output. SHDN is high-voltage
compatible and is connected to IN for normal operation.
4, 9, 15
4, 9, 14, 15
GND
Ground
5
5
COMP
6
6
SC
Open-Drain Short-Circuit Indicator Output. SC goes low when the load current is greater
than the set short-circuit current threshold or when there is a short-to-battery fault.
Connect SC to a 10kI pullup resistor. See Table 1.
7
7
OL
Open-Drain Open-Load Indicator Output. OL goes low when the load current is lower
than the set open-load current threshold or when there is a short-to-battery fault. Connect
OL to a 10kI pullup resistor. See Table 1.
8
8
AOUT
Current Monitor Voltage Output. AOUT can be used to measure the load current by
means of an external ADC. AOUT has a current drive capability of 1mA. Bypass AOUT to
GND with a 15nF ceramic capacitor. See Table 1.
10
10
OLT
Open-Load Current Threshold Setting Input. A resistive divider between REF, OLT, and
GND sets the open-load current threshold.
11
11
LIM
Current-Limit Setting input. Connect a resistive divider from REF, LIM, and GND to set
the current limit of the switch or LDO. Alternatively, externally drive LIM (not to exceed
3.65V) to set the current limit.
10 Input Voltage. Bypass IN to GND with a low-ESR ceramic capacitor with a minimum
value of 0.1FF.
LDO Compensation. Connect a 0.1FF ceramic capacitor between COMP and GND to
compensate the LDO.
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Pin Description (continued)
PIN
NAME
FUNCTION
MAX16946
MAX16947
12
12
REF
+3V Nominal Reference Output. REF has a current drive capability of 100FA.
13
13
REG
Internal Regulator +5V Output. REG powers all internal blocks. Do no use REG to supply
power to external circuitry. Bypass REG to GND with a 1FF capacitor.
Feedback Input (MAX16946 Only). Connect FB to GND to configure the MAX16946 as
a switch. Connect FB to REG for an LDO with a fixed 8.5V output. Connect to the center
tap of an external resistive divider connected between OUT and GND to adjust the
output voltage of the LDO.
14
—
FB
16
—
OUT
Switch or LDO Output (MAX16946 Only). OUT is either a switch or LDO output
depending on the connection of FB.
—
16
OUT
Switch Output
—
—
EP
Exposed Pad (MAX16946 Only). Connect EP to the ground plane for optimal heat
dissipation. Do not use EP as the only electrical ground connection.
Detailed Description
The MAX16946/MAX16947 high-voltage, high-side, current-sense LDO/switches feature internal current limiting
to prevent system damage due to fault conditions. The
MAX16946 provides a regulated 8.5V output voltage
fixed or adjustable from 3.3V to 15V. The MAX16946 can
also be configured as a switch, while the MAX16947 is
only available as a switch. The input voltage range for
both devices extends from 4.5V to 18V (45V tolerant),
making the devices ideal for providing phantom power
to remote radio-frequency low-noise amplifiers (LNAs) in
automotive applications.
The devices monitor the load current and provide an
analog output voltage proportional to the sensed load
current. Accurate internal current-limit protects the input
supply against both overload and short-circuit conditions. Two open-drain fault indicator outputs indicate to
the microprocessor when a short circuit, an open-load
condition, or a short-to-battery condition exists. An overtemperature shutdown is also indicated by means of the
current-sense amplifier’s output voltage.
A fault-blanking feature allows the devices to ignore
momentary faults such as those caused by the charging of capacitive loads during hot-swapping, preventing false alarms to the system. The devices feature
short-to-battery protection to latch off the internal LDO/
pass switch during a short-to-battery event and thermal
Maxim Integrated
overload. They include an active-low, high-voltagecompatible shutdown input to place them in low-power
shutdown mode.
Current-Sense Amplifier
The integrated current-sense amplifier employs a differential amplifier that amplifies the voltage between IN and
SENS. A sense resistor, RSENSE, is connected across IN
and SENS. Typical sense resistor values range between
0.25I and 2I. When the load current passes through
the sense resistor, a voltage drop develops across it.
The current-sense amplifier amplifies this voltage.
The current-sense amplifier features an internally fixed
gain of AV = 26V/V (typ). The following equations show
the relationship between the current-sense amplifier
output voltage (VAOUT) and load current:
(VIN − VSENS )(V) = ILOAD (A) × R SENSE (Ω)
VAOUT (=
V) A V (V V) × (VIN − VSENS ) (V) + 0.4V
If LIM is connected to REF, the maximum output voltage
of AOUT is VAOUT_FS = 3V. If LIM is externally driven to
3.65V, the maximum output voltage of AOUT extends
to VAOUT_FS = 3.65V. The maximum AOUT voltage is
always equal to VLIM, the voltage at LIM.
AOUT is the output of an internal buffer with 1mA current
drive capability. Bypass AOUT to ground with a 15nF
ceramic capacitor.
11
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Load Protection
The devices monitor the load current through an external
sense resistor and perform the following actions:
U If the monitored current is lower than the set openload current, the devices signal that there is an openload (see the Open Load section).
U If the monitored current is greater than the set shortcircuit current (ISC), the devices enter the shortcircuit mode (see the Short Circuit and Current Limit
section).
The devices also perform a short-to-battery detection
before the internal switch turns on. During normal operation, reverse-current detection protects the devices from
short-to-battery events (see the Short-to-Battery and
Reverse-Current Detection section).
In addition, thermal shutdown protects the devices from
overheating (see the Thermal Shutdown section).
Two open-drain fault indicator outputs (OL and SC) and the
AOUT voltage indicate the devices’ status (Table 1).
Open Load
If the load current drops below the open-load current threshold, the OL output latches low. An openload condition does not turn off the internal switch. To
unlatch the OL output, pulse SHDN low for less than
tSHDN_OFF (150Fs min). Keeping SHDN low for longer than
tSHDN_OFF shuts down the device.
The open-load current threshold is adjustable. Connect
a resistive divider between REF, the open-load current
threshold adjustment input (OLT), and GND to set the
open-load current threshold (see the Open-Load Current
Threshold Selection section).
Short Circuit and Current Limit
If the load current exceeds the set short-circuit current threshold (ISC), the tBLANK timer begins counting.
During this period, the load current is limited to the
current limit set by the voltage at LIM. If the overcurrent
condition persists beyond tBLANK, SC asserts low and
the internal switch turns off. The timer resets if the overcurrent condition disappears before the blanking time
(tBLANK) has elapsed.
If the switch is turned off at the end of tBLANK, a retry
timer (tRETRY) starts immediately after the blanking time
has elapsed, and during that time the switch stays off.
At the end of tRETRY, the switch turns on again while
SC stays low. If the fault still exists, the cycle repeats. If
the fault has been removed, the switch stays on and SC
goes high after the blanking time tBLANK. During retry
when the switch is off, the current through the switch is
zero. Blanking time and retry time have fixed values of
100ms (min) and 1100ms (min), respectively.
Figures 1–4 show the response of the devices to the
presence and removal of overcurrent conditions.
The current-limit threshold is adjustable. Connect a
resistive divider between REF, the current-limit setting
input (LIM), and GND to set the current-limit threshold.
Alternatively, externally drive LIM (not to exceed 3.65V)
to set the current-limit threshold (see the Current-Limit
Threshold Selection section).
The short-circuit current threshold depends on the value
of the sense resistor and is calculated as follows:
I SC =
1.3V
R SENSE × A V
where AV is the gain of the internal current-sense amplifier and is equal to 26V/V and RSENSE is the sense resistor value.
12 Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ILIM
ISC
LOAD
CURRENT
tBLANK
tRETRY
tBLANK
tRETRY
tBLANK
t
SHDN
SC
Figure 1. Turn-On into Temporary Short Circuit
ILIM
ISC
LOAD
CURRENT
tBLANK
t
SHDN
SC
Figure 2. Turn-On into Hard Short Circuit
Maxim Integrated
13
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
ILIM
ISC
LOAD
CURRENT
tBLANK
tRETRY
tBLANK
t
SHDN
SC
Figure 3. Turn-On into Temporary Heavy Load
ILIM
ISC
LOAD
CURRENT
tBLANK
tRETRY
tBLANK
t
SHDN
SC
Figure 4. Turn-On into Heavy Load
14 Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Short-to-Battery and Reverse-Current Detection
It is possible for OUT to be shorted to the battery due to
a fault in the system. The devices detect this failure by
comparing the OUT voltage and the IN voltage before
the switch turns on. Every time the switch turns on, such
as at the end of the retry time, or once the thermal shutdown condition disappears, the short-to-battery detection is performed. At this point, if the device detects the
short-to-battery fault, the switch stays off and both SC
and OL assert low (Table 1).
Series inductance and the output capacitor can produce
ringing during a short-circuit condition, resulting in an
output voltage that temporarily exceeds the input voltage. Blanking is implemented during and immediately
after a short-circuit event to prevent false triggering of
the reverse-current detection. The reverse-current blanking time (tREV_BLANK) is 16ms (typ). If the reverse current produces a VSENSE (VIN - VSENSE) less than -7.7mV
(typ) for a duration greater than the blanking time, the
device latches off the switch and both SC and OL assert
low.
Thermal Shutdown
Thermal-shutdown circuitry protects the devices from
overheating. The switch turns off immediately when the
junction temperature exceeds +170NC (typ) (Table 1).
The switch turns on again after the device temperature
drops by approximately +15NC (typ). Thermal shutdown
is indicated by 0V on AOUT.
Undervoltage and Overvoltage Lockout
The devices include undervoltage lockout circuitry
(UVLO) to prevent erroneous switch operation when the
input voltage goes below 3.5V (typ) during startup and
brownout conditions. Input voltages of less than 3.5V
inhibit operation of the device by turning off the internal
charge pump and the switch.
These devices also feature an overvoltage lockout
(OVLO) threshold of 21V (typ). When VIN is greater than
VOVLO, the device immediately turns off the switch and
the internal charge pump.
Shutdown (SHDN)
The devices feature an active-low shutdown input
(SHDN) to place them into a low-power shutdown mode.
The devices turn off and consume a 7FA maximum (at
VIN = 12V) of shutdown current when SHDN is driven
low for greater than 360Fs. Driving SHDN high initiates
a device turn-on with short-to-battery detection. Pulsing
SHDN low for less than tSHDN_OFF clears the OL output.
Internal Reference (REF)
The devices feature a 3V bandgap reference output, stable over supply voltage and temperature. The reference
has a current drive capability of 100FA. Use resistive
dividers connected to REF to set the open-load current
threshold and the current-limit threshold. Do not use REF
to drive external circuitry.
Internal +5V Linear Regulator (REG)
The devices feature an internal regulator that regulates
the input voltage to +5V to power all internal circuitry.
Bypass the regulator output (REG) to GND with a 1FF
ceramic capacitor. Do not use this regulator to power
external circuitry.
Table 1. MAX16946/MAX16947 Status Truth Table
VAOUT (V)
DEVICE STATUS
ACTION TAKEN
SC
1
OL
1
(ILOAD O RSENSE) O 26 + 0.4
Normal operation
None
0
1
(ILOAD O RSENSE) O 26 + 0.4
Short circuit
Autoretry
1
0
(ILOAD O RSENSE) O 26 + 0.4
Open load
Reverse current (on-state)
OL latched low
Switch/LDO latched off
OUT short-to-battery (off-state),
VOUT too high ( LDO mode)
Switch/LDO turned off as long as condition
persists
Thermal shutdown, VIN
overvoltage, VIN undervoltage
Switch/LDO and AOUT turns off as long as
condition persists
REF undervoltage
Switch/LDO, AOUT, and REF turned off as
long as condition persists
0
1
0
1
Maxim Integrated
0.4 after switching off
0
15
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Applications Information
Choosing the Sense Resistor
Ideally, the maximum load current develops the full-scale
sense voltage across the current-sense resistor. The
current-sense amplifier output voltage is given by:
VAOUT = AV x (VIN - VSENS) + 0.4V
where VAOUT is the output voltage of the current-sense
amplifier, and AV is the gain of the current-sense amplifier of 26V/V (typ).
Calculate the maximum value for RSENSE, so that the
amplified differential voltage across IN and SENS does
not exceed the short-circuit AOUT voltage threshold
of VSC = 1.7V (typ), which is defined in the Electrical
Characteristics table:
R SENSE =
VSC − 0.4V
ILOAD(FULL_SCALE) × A V
Typical sense resistor values range between 0.25I and
2I.
During normal operation, when the load current is less
than the short-circuit current threshold, the maximum
AOUT voltage is equal to VSC. When a short circuit to
ground is present and the device goes into autoretry,
the maximum AOUT voltage extends to VLIM, the voltage at LIM.
Keep inductance low if ISENSE has a large highfrequency component. Wire-wound resistors have the
highest inductance, while metal film is somewhat better.
Low-inductance, metal-film resistors are also available.
Instead of being spiral wrapped around a core, as in
metal-film or wire-wound resistors, they are a straight
band of metal and are available in values under 1I.
Because of the high current that flows through RSENSE,
eliminate parasitic trace resistance from causing errors
in the sense voltage.
Open-Load Current Threshold Selection
A resistive divider between REF, OLT, and GND sets the
open-load current threshold. See Figure 5.
Use the following formula to set the desired open-load
current threshold:
R2 =
R1


VREF
− 1

R
I
A
0.4V
×
×
+
V
 SENSE OL

where IOL is the desired open-load current threshold,
AV is the current-sense amplifier gain (26V/V typical),
and VREF is the reference voltage (3V typ). Size R1 and
R2 large enough so that the equivalent resistance of the
resistive dividers used to set the open-load and currentlimit thresholds does not exceed the REF output 100FA
drive capability.
For example, to set the open-load current threshold at
10mA, using a 0.5I sense resistor, use the following
method to calculate the value of R1 and R2:
R2 =
R1


3V
 0.5Ω × 0.01A × 26V/V+0.4V − 1


Choose R1 = 470kI and calculate R2 as 100kI.
REF
MAX16946
MAX16947
REF
R1
OLT
R1
LIM
R2
Figure 5. Open-Load Current Threshold Selection
16 MAX16946
MAX16947
R2
Figure 6. Current-Limit Threshold Selection
Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Current-Limit Threshold Selection
A resistive divider between REF, LIM, and GND sets the
current-limit threshold. See Figure 6.
Use the following formula to set the desired current-limit
threshold:
R1
R2 =


VREF
− 1

 R SENSE × ICL × A V + 0.4V 
R2 =
R1
 VOUT 
− 1

 VFB

Select R1 so that the maximum input bias current at FB
is negligible compared to the total current going through
R1.
Compensation Capacitor
where ICL is the desired current-limit threshold, AV is the
current-sense amplifier gain (26V/V typ), and VREF is the
reference voltage (3V typ). Size R1 and R2 large enough
so that the equivalent resistance of the resistive dividers
used to set the open-load and current-limit thresholds
does not exceed the REF output 100FA drive capability.
For example, to set the current-limit threshold at 120mA,
using a 0.5I sense resistor, use the following method to
calculate the value of R1 and R2:
R2 =
R1


3V
 0.5Ω × 0.120A × 26V/V+0.4V − 1


Choose R1 = 83kI and calculate R2 as 156kI.
Using an External Reference
Use an external reference with resistive dividers as an
alternative means of setting the current-limit and openload current thresholds. The equations shown in the
Open-Load Current Threshold Selection and CurrentLimit Threshold Selection sections are still applicable
when using an external reference. In those equations,
set VREF equal to the voltage of the external reference.
When using the devices’ 3V reference, the maximum
voltage at LIM is VLIM = 3V and is obtained by connecting LIM to REF. When using an external reference, set
the voltage at LIM to no greater than VLIM(MAX) = 3.65V.
Compensate the LDO regulator by bypassing COMP to
GND with a 0.1FF ceramic capacitor.
Input Capacitor
Connect a low-leakage ceramic capacitor from IN to
GND to limit the input-voltage drop during momentary
output short-circuit conditions and to protect the device
against transients due to inductance in the IN line. For
example, use at least a 0.1FF ceramic capacitor if the
input inductance (including any stray inductance) is
estimated to be 20FH. Larger capacitor values reduce
the voltage undershoot and voltage overshoot in case of
reverse current at the input.
Output Capacitor
In an analogous fashion to the input capacitor, an output
capacitor protects the device against transients due to
any series inductance in the output. Under no conditions
should the voltage on OUT go below -0.3V as specified
in the Absolute Maximum Ratings section. A Schottky
diode is required to clamp transients that go below
ground. For example, with a 2.2mH series inductance,
to avoid excessive ringing at the output, bypass OUT to
GND with not more than 0.1FF capacitance. Additionally,
bypassing OUT to GND with a 2.2FF ceramic capacitor
in series with a 10I resistor reduces ringing caused by
load current transients through a maximum 2.2mH series
inductance.
Fixed/Adjustable Output Voltage
The MAX16946 is configurable to provide a fixed 8.5V
output or as an adjustable LDO with an output between
3.3V and 15V. Connect a resistive divider between OUT,
FB, and GND to set the output to the desired voltage, as
shown in Figure 7. Connect FB to REG to configure the
MAX16946 as an 8.5V LDO, as shown in Figure 8. FB is
regulated to 1.0V with Q3% accuracy for a load current
between 5mA and 150mA. The accuracy falls to Q5% for
a load current between 2mA and 200mA. Select a value
for R1 and calculate R2 as follows:
Maxim Integrated
OUT
R1
MAX16946
FB
R2
Figure 7. Adjustable Output-Voltage Selection
17
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Layout and Thermal Dissipation
If the output is continuously shorted to ground at the maximum supply voltage, the devices are protected because
the total power dissipated during the short is scaled
down by the duty cycle imposed by the protection:
To optimize the switch response time to output shortcircuit condition, it is very important to keep all traces
as short as possible to reduce the effect of undesirable
parasitic inductance. Place input and output capacitors
as close as possible to the device (no more than 5mm).
IN and OUT must be connected with wide short traces
to the power bus. During normal operation in switch
mode, the power dissipation is small and the package
temperature change is minimal. In LDO mode, the power
dissipation is given by:
P(MAX) =
VVIN(MAX) × I OUT(MAX) × t BLANK
t RETRY + t BLANK
(VIN - VOUT) x ILOAD + VIN x IIN
BATTERY INPUT
RSENSE
LOUT
CIN
IN
SENS
OUT
COUT
FB
C SUPPLY
MAX16946
REGULATED
PHANTOM
SUPPLY
R5
R6
COMP
RPU
ERROR
FLAGS
REG
REF
SC
OL
CURRENTSENSE
OUTPUT
AOUT
ON/OFF
SHDN
R1
R3
R2
R4
LIM
GND
OLT
Figure 8. LDO with Adjustable Output Voltage (3.3V to 15V)
18 Maxim Integrated
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
BATTERY INPUT
RSENSE
LOUT
REGULATED
PHANTOM
SUPPLY
CIN
IN
SENS
OUT
COUT
FB
C SUPPLY
MAX16946
COMP
RPU
REG
REF
SC
ERROR
FLAGS
OL
CURRENTSENSE
OUTPUT
AOUT
ON/OFF
SHDN
R1
R3
R2
R4
LIM
GND
OLT
Figure 9. LDO with Fixed 8.5V Output
BATTERY INPUT
RSENSE
LOUT
REGULATED
PHANTOM
SUPPLY
CIN
IN
SENS
OUT
COUT
FB
(GND)
C SUPPLY
COMP
RPU
ERROR
FLAGS
CURRENTSENSE
OUTPUT
REG
REF
SC
OL
MAX16946
MAX16947
R1
R3
R2
R4
LIM
AOUT
SHDN
GND
OLT
() MAX16947
Figure 10. Input Switched to Output
Maxim Integrated
19
MAX16946/MAX16947
Remote Antenna, Current-Sense and
LDO/Switches
Chip Information
PROCESS: BiCMOS
Package Information
For the latest package outline information and land patterns, 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
20 PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN
NO.
16 QSOP
E16+5
21-0055
90-0167
16 QSOP-EP
E16E+10
21-0112
90-0239
16 TQFN-EP
T1644+4
21-0139
90-0070
Maxim Integrated
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