General Description
The MAX9918/MAX9919/MAX9920 are single-supply,
high-accuracy current-sense amplifiers with a high
input common-mode range that extends from -20V
to +75V. These amplifiers are well suited for current
monitoring of inductive loads such as motors and
solenoids, where common-mode voltages can become
negative due to inductive kickback, reverse-battery
conditions, or transient events.
The MAX9918/MAX9920 feature adjustable gain set
by an external resistive-divider network. The MAX9919
features fixed gains of 45V/V (MAX9919F) and 90V/V
(MAX9919N). The MAX9918/MAX9919/MAX9920
operate as unidirectional amplifiers when VREFIN = GND
and as bidirectional amplifiers when VREFIN = VCC/2.
The MAX9920 attenuates the input signal by a factor of
4 at the input level-shifting stage allowing the device to
sense voltages up to 200mV (unidirectional operation) or
±100mV (bidirectional operation).
The MAX9918/MAX9919/MAX9920 operate with a
single 5V supply voltage, are fully specified over the
-40°C to +125°C automotive temperature range, and are
available in an 8-pin SOIC package.
Applications
●H-Bridge Motor Current Sensing
●Solenoid Current Sensing
●Current Monitoring of Inductive Loads
●High- and Low-Side Precision Current Sensing
●Super-Capacitor Charge/Discharge Monitoring
●Precision High-Voltage Current Monitoring
●Automotive
Benets and Features
●Reduce Protective Clamping for High Inductive
Kickback Voltage
• -20V to +75V Input Common-Mode Voltage Range
●Supports Wide Range of Precision AC and DC
Current Sensing Applications
• Uni- or Bidirectional Current Sensing
• 0.6% (max) Gain Accuracy Error
• 400µV (max) Input O󰀨set Voltage
• 120kHz, -3dB Bandwidth (MAX9919N)
• Reference Input for Bidirectional OUT
• Rail-to-Rail Output
●Saves Board Space
• 8-Pin SOIC Package
• Single-Supply Operation (4.5V to 5.5V)
●AEC-Q100 Qualified (MAX9918ASA/V+,
MAX9919FASA/V+, MAX9919NASA/V+,
MAX9920ASA/V+ Only)
19-5015; Rev 9; 2/19
Click here for production status of specic part numbers.
Note: All devices operate over the -40°C to +125°C temperature range.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
*EP = Exposed pad.
M
ø2B
ø1B
ADC
REF
A
INPUT STAGE
LEVEL SHIFTER
RSENSE
VBATT
ADJUSTABLE GAIN
VCC VCC
RS+
RS-
FB
OUT
REFIN
R2
R1
GND
GND
SHDN
ø2B
ø1A MAX9918
MAX9920
µC
Typical Operating Circuit
Ordering Information/Selector Guide
PART VSENSE
(mV)
GAIN
(V/V)
PIN-
PACKAGE
MAX9918ASA+ ±50 Adjustable 8 SO-EP*
MAX9918ASA/V+ ±50 Adjustable 8 SO-EP*
MAX9919FASA+ ±50 45 8 SO-EP*
MAX9919FASA/V+ ±50 45 8 SO-EP*
MAX9919NASA+ ±50 90 8 SO-EP*
MAX9919NASA/V+ ±50 90 8 SO-EP*
MAX9920ASA+ ±200 Adjustable 8 SO-EP*
MAX9920ASA/V+ ±200 Adjustable 8 SO-EP*
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
VCC to GND ............................................................-0.3V to +6V
RS+, RS- to GND (VCC = 5V) ................................ -30V to +80V
RS+, RS- to GND (VCC = 0V) ...........-15V to +80V (15 minutes)
Differential Input Voltage (VRS+ - VRS-)
(MAX9918/MAX9919) ................................±15V (Continuous)
Differential Input Voltage
(VRS+ - VRS-) (MAX9920) ...........................±5V (Continuous)
REFIN, FB, OUT to GND ......................... -0.3V to (VCC + 0.3V)
SHDN to GND .......................................................-0.3V to +20V
Output Short Circuit to VCC or GND .........................Continuous
Continuous Current into Any Pin
(Not to exceed package power dissipation) .................±20mA
Continuous Power Dissipation (TA = +70°C)
8-Pin SO-EP (derate 24.4mW/°C above +70°C) .. 1951.2mW**
Junction Temperature ...................................................... +150°C
Storage Temperature Range ............................ -65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) ....................................... +260°C
SO-EP
Junction-to-Ambient Thermal Resistance (θJA) ..........41°C/W
Junction-to-Case Thermal Resistance (θJC) .................7°C/W
**As per JEDEC51 Standard (multilayer board).
(Note 1)
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.
Absolute Maximum Ratings
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.
Package Thermal Characteristics
8 SO-EP
PACKAGE CODE S8E+14
Outline Number 21-0111
Land Pattern Number 90-0151
Thermal Resistance, Single-Layer Board:
Junction to Ambient (θJA) 52°C/W
Junction to Case (θJC) 6°C/W
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA) 41°C/W
Junction to Case (θJC) 7°C/W
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.
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 Information
www.maximintegrated.com Maxim Integrated
│
2
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, VRS+ = VRS- = +14V, VSENSE = (VRS+ - VRS-) = 0V, VSHDN = VGND = 0V, VREFIN = VCC/2, RL = 100kΩ; for MAX9918,
AV = 90V/V, R2/R1 = 89kΩ/1kΩ; for MAX9920, AV = 20V/V, R2/R1 = 79kΩ/1kΩ; TA = -40°C to +125°C, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
Electrical Characteristics
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Input O󰀨set Voltage (Note 2) VOS
MAX9918
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = +25°C ±0.14 ±0.4
mV
TA = -40°C to
+125°C ±0.7
VRS+ = VRS- =
-2V, VREFIN
= 0V
TA = +25°C ±0.08 ±0.4
TA = -40°C to
+125°C ±1.3
MAX9919_
VRS+= VRS- =
+14V, VREFIN
= 0V
TA = +25°C ±0.18 ±0.4
TA = -40°C to
+125°C ±0.9
VRS+ = VRS- =
-2V, VREFIN
= 0V
TA = +25°C ±0.11 ±0.4
TA = -40°C to
+125°C ±1.0
MAX9920
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = +25°C ±0.48 ±1.2
TA = -40°C to
+125°C ±3.0
VRS+ = VRS- =
-2V, VREFIN
= 0V
TA = +25°C ±0.10 ±0.9
TA = -40°C to
+125°C ±3.5
www.maximintegrated.com Maxim Integrated
│
3
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, VRS+ = VRS- = +14V, VSENSE = (VRS+ - VRS-) = 0V, VSHDN = VGND = 0V, VREFIN = VCC/2, RL = 100kΩ; for MAX9918,
AV = 90V/V, R2/R1 = 89kΩ/1kΩ; for MAX9920, AV = 20V/V, R2/R1 = 79kΩ/1kΩ; TA = -40°C to +125°C, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
Electrical Characteristics (continued)
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
Input O󰀨set Voltage Drift
(Note 3) VOSD
MAX9918 VRS+ = VRS- = +14V ±1.2
µV/°C
VRS+ = VRS- = -2V ±3.3
MAX9919_ VRS+ = VRS- = +14V ±1.8
VRS+ = VRS- = -2V ±1.8
MAX9920 VRS+ = VRS- = +14V ±2.4
VRS+ = VRS- = -2V ±8.8
Common-Mode Range VCM Inferred from CMRR tests -20 +75 V
Common-Mode Rejection Ratio
(Note 3) CMRR
MAX9918,
MAX9919
-2V ≤ VCM ≤ +14V 80
dB
-20V ≤ VCM ≤ +75V 96
MAX9920 -2V ≤ VCM ≤ +14V 72
-20V ≤ VCM ≤ +75V 86
Input Bias Current IRS+, IRS- -20V ≤ VCM ≤ +75V TA = +25°C ±175 µA
TA = -40°C to +125°C ±250
Input O󰀨set Current (IRS+ - IRS-) 0 ±8 µA
Input Leakage Current in
Shutdown -20V ≤ VCM ≤ +75V, VSHDN = VCC = 5V ±30 µA
Input Leakage Current VRS+ = VRS- = +14V, +75V, VCC = 0V ±30 µA
Input Resistance
MAX9918,
MAX9919_
Common mode 300 kΩ
Di󰀨erential 715 Ω
MAX9920 Common mode 330 kΩ
Di󰀨erential 224 Ω
Full-Scale Sense Voltage
(Note 4) VSENSE Inferred from gain
error test
MAX9918, MAX9919_ 50 mV
MAX9920 200
Gain (Notes 2, 4) G
MAX9918, MAX9920 Adj
V/VMAX9919F 45
MAX9919N 90
Minimum Adjustable Gain GADJ
MAX9918 30 V/V
MAX9920 7.5
www.maximintegrated.com Maxim Integrated
│
4
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, VRS+ = VRS- = +14V, VSENSE = (VRS+ - VRS-) = 0V, VSHDN = VGND = 0V, VREFIN = VCC/2, RL = 100kΩ; for MAX9918,
AV = 90V/V, R2/R1 = 89kΩ/1kΩ; for MAX9920, AV = 20V/V, R2/R1 = 79kΩ/1kΩ; TA = -40°C to +125°C, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
Electrical Characteristics (continued)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Gain Error
(Note 2) GE
MAX9918
VRS+ = VRS- =
+14V
TA = +25°C,
VREFIN = 0V ±0.08 ±0.6
%
TA = -40°C to
+125°C,
VREFIN = 0V
±1.2
VRS+= VRS- =
-2V, VREFIN
= 0V
TA = +25°C±0.02 ±0.6
TA = -40°C to
+125°C±1.0
MAX9919F
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = +25°C±0.13 ±0.45
TA = -40°C to
+125°C±1.2
VRS+= VRS- =
-2V, VREFIN
= 0V
TA = +25°C±0.10 ±0.45
TA = -40°C to
+125°C±0.9
MAX9919N
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = +25°C±0.16 ±0.6
TA = -40°C to
+125°C±1.2
VRS+ = VRS- =
-2V, VREFIN
= 0V
TA = +25°C±0.11 ±0.6
TA = -40°C to
+125°C±1.0
MAX9920
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = +25°C ±0.29 ±1.0
TA = -40°C to
+125°C±1.7
VRS+ = VRS- =
-2V, VREFIN
= 0V
TA = +25°C±0.24 ±1.0
TA = -40°C to
+125°C±1.7
Output-Voltage High (Note 4) VCC - VOH
VSENSE = 200mV for
MAX9918, MAX9919_,
VSENSE = 400mV for
MAX9920
RL = 100kΩ to GND 3 10
mV
RL = 10kΩ to GND 12 40
Output-Voltage Low (Note 4) VOL
VSENSE = -200mV for
MAX9918, MAX9919_,
VSENSE = -400mV for
MAX9920
RL = 100kΩ to VCC 3 10
mV
RL = 10kΩ to VCC 10 40
Short-Circuit Current ISC
OUT shorted to VCC 44 mA
OUT shorted to GND 41
Output Resistance ROUT 0.1 Ω
REFIN Voltage Range Inferred from REFIN
CMRR test
MAX9918,
MAX9919_ 0 VCC/2 VCC -
1.9 V
MAX9920 0 VCC/2 VCC -
2.4
www.maximintegrated.com Maxim Integrated
│
5
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, VRS+ = VRS- = +14V, VSENSE = (VRS+ - VRS-) = 0V, VSHDN = VGND = 0V, VREFIN = VCC/2, RL = 100kΩ; for MAX9918,
AV = 90V/V, R2/R1 = 89kΩ/1kΩ; for MAX9920, AV = 20V/V, R2/R1 = 79kΩ/1kΩ; TA = -40°C to +125°C, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
Electrical Characteristics (continued)
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
REFIN Common-Mode Rejection
Ratio REFINCMRR
MAX9918, MAX9919_ 0V ≤ VREFIN ≤ (VCC
- 1.9V) 82 103
dB
MAX9920 0V ≤ VREFIN ≤ (VCC
- 2.4V) 75 90
REFIN Current IREFIN
MAX9918, MAX9919_, VRS+ = VRS- = ±50mV ±100 µA
MAX9920, VRS+ = VRS- = ±200mV ±100
SHDN Logic-High VIH 2.0 V
SHDN Logic-Low VIL 0.8 V
SHDN Logic Input Current 0 ≤ VSHDN ≤ VCC 5 µA
Supply Voltage Range VCC Inferred from PSRR test 4.5 5.5 V
Power-Supply Rejection Ratio
(Note 3) PSRR MAX9918, MAX9919_ 4.5V ≤ VCC ≤ 5.5V 74 103 dB
MAX9920 4.5V ≤ VCC ≤ 5.5V 68 100
Supply Current ICC
VRS+ = VRS- = +14V TA = +25°C 0.7 1.2
mA
TA = -40°C to +125°C 1.5
VRS+ = VRS- = -2V TA = +25°C 1.0 1.6
TA = -40°C to +125°C 2.2
Shutdown Supply Current ICC_SHDN VSHDN = VCC = 5V 0.5 10 µA
Small Signal -3dB Bandwidth BW
MAX9918, VSENSE = 50mV 75
kHz
MAX9919F, VSENSE = 50mV 250
MAX9919N, VSENSE = 50mV 120
MAX9920, VSENSE = 200mV 230
Slew Rate SR
MAX9918 0.6
V/µs
MAX9919F 0.9
MAX9919N 3.0
MAX9920 1.5
1% Settling Time from VSENSE
Step
MAX9918 VSENSE = 5mV to 50mV step 12
µs
VSENSE = 50mV to 5mV step 7
MAX9919F VSENSE = 5mV to 50mV step 3.5
VSENSE = 50mV to 5mV step 2.5
MAX9919N VSENSE = 5mV to 50mV step 3.5
VSENSE = 50mV to 5mV step 3
MAX9920 VSENSE = 20mV to 200mV step 5
VSENSE = 200mV to 20mV step 3
www.maximintegrated.com Maxim Integrated
│
6
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
Note 1: All devices are 100% production tested at TA = +25°C. All temperature limits are guaranteed by design.
Note 2: VOS is extrapolated from two point gain error tests. Measurements are made at VSENSE = 5mV and 50mV for MAX9918/
MAX9919N/MAX9919F, and VSENSE = 20mV and 200mV for MAX9920.
Note 3: Extrapolated VOS as described above in Note 2 is used to calculate VOS drift, CMRR, and PSRR.
Note 4: OUT should be 100mV away from either rail to achieve rated accuracy, or limited by a VSENSE of 50mV for the MAX9918/
MAX9919N/MAX9919F and 200mV for the MAX9920.
Note 5: Not production tested. Guaranteed by design.
(VCC = 5V, VRS+ = VRS- = +14V, VSENSE = (VRS+ - VRS-) = 0V, VSHDN = VGND = 0V, VREFIN = VCC/2, RL = 100kΩ; for MAX9918,
AV = 90V/V, R2/R1 = 89kΩ/1kΩ; for MAX9920, AV = 20V/V, R2/R1 = 79kΩ/1kΩ; TA = -40°C to +125°C, unless otherwise noted. Typical
values are at TA = +25°C.) (Note 1)
Electrical Characteristics (continued)
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
1% Settling Time from VCM Step
MAX9918,
VSENSE = 50mV
VCM = -2V to +14V step 2.5
µs
VCM = +14V to -2V step 0.5
MAX9919F,
VSENSE = 50mV
VCM = -2V to +14V step 2.5
VCM = +14V to -2V step 0.5
MAX9919N,
VSENSE = 50mV
VCM = -2V to +14V step 3.5
VCM = +14V to -2V step 3.5
MAX9920,
VSENSE = 200mV
VCM = -2V to +14V step 0.25
VCM = +14V to -2V step 2.5
Power-Up Time
MAX9918, VSENSE = 50mV, 1% settling 4.5
µs
MAX9919F, VSENSE = 50mV, 1% settling 5
MAX9919N, VSENSE = 50mV, 1% settling 6
MAX9920, VSENSE = 200mV, 1% settling 5
Max Capacitive Load Stability No sustained oscillations (Note 5) 50 pF
Input-Referred Noise Voltage
Density en10kHz MAX9918, MAX9919_ 60 nV/√Hz
MAX9920 174
www.maximintegrated.com Maxim Integrated
│
7
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
VOS DRIFT
(VRS+ = +14V)
MAX9918 toc02
OFFSET VOLTAGE (µV/°C)
N (%)
3210-1-2-3
0.05
0.10
0.15
0.20
0.25
0.30
0
-4 4
VOS
(VRS+ = -2V)
MAX9918 toc03
OFFSET VOLTAGE (µV)
N (%)
320240160800-80-160-240-320
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0
-400 400
VOS DRIFT
(VRS+ = -2V)
MAX9918 toc04
OFFSET VOLTAGE (µV/°C)
N (%)
84 6-6 -4 -2 0 2-8
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0
-10 10
VOS vs. VCM
MAX9918 toc05
V
CM
(V)
VOS (µV)
706040 500 10 20 30-10
-400
-300
-200
-100
0
100
200
300
400
500
-500
-20 80
TA = -40°C
TA = +25°C
MAX9918ASA
VCC = 5V
VREF = VGND
TA = +125°C
VOS vs. VCC
MAX9918 toc06
V
CC
(V)
VOS (µV)
5.45.35.1 5.24.7 4.8 4.9 5.04.6
-75
-50
-25
0
25
50
75
100
125
-100
4.5 5.5
MAX9918ASA
VCC = 5V
VREF = VGND
VCM = -2V
VCM = 14V
0 0.1 0.2 0.3-0.4 -0.3 -0.2 -0.1 0.4
GAIN ERROR
(VRS+ = +14V, MAX9919F, AV = +45V/V)
MAX9918 toc07
GAIN ERROR (%)
N (%)
0.1
0.2
0.3
0.4
0.5
0.6
0
VOS
(VRS+ = +14V)
MAX9918 toc01
OFFSET VOLTAGE (µV)
N (%)
240 320-240-160 -80 0 80 160-320
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
0.45
0.50
0
-400 400
0 0.1 0.2 0.3-0.4 -0.3 -0.2 -0.1 0.4
GAIN ERROR (%)
MAX9918 toc08
N (%)
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0
GAIN ERROR
(VRS+ = +14V, MAX9919N, AV = +90V/V)
0 0.1 0.2 0.3-0.4 -0.3 -0.2 -0.1 0.4
GAIN ERROR
(VRS+ = -2V, MAX9919F, AV = +45V/V)
MAX9918 toc09
GAIN ERROR (%)
N (%)
0.1
0.2
0.3
0.4
0.5
0.6
0
www.maximintegrated.com Maxim Integrated
│
8
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
0 0.1 0.2 0.3-0.4 -0.3 -0.2 -0.1 0.4
GAIN ERROR
(VRS+ = -2V, MAX9919N, AV = +90V/V)
MAX9918 toc10
GAIN ERROR (%)
N (%)
0.1
0.2
0.3
0.4
0.5
0.6
0
GAIN ERROR vs. VCC
MAX9918 toc12
VCC (V)
GAIN ERROR (%)
5.35.14.94.7
-0.4
-0.3
-0.2
-0.1
0
0.1
0.2
0.3
0.4
0.5
-0.5
4.5 5.5
VCM = -2V
VCM = 14V
LINEARITY vs. VSENSE
MAX9918 toc14
LINEARITY (%)
20100-10-20
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
-30 30
VCM = +14V
VCC = 5V
VREFIN = VCC/2
AV = 90V/V
BIDIRECTIONAL
TA = -40°CTA = +25°C
TA = +125°C
VSENSE (mV)
GAIN ERROR vs. VCM
MAX9918 toc11
VCM (V)
GE (%)
706040 500 10 20 30-10
-1.6
-1.2
-0.8
-0.4
0
0.4
0.8
1.2
1.6
2.0
-2.0
-20 80
MAX9918ASA
VCC = 5V
VREF = VGND
TA = +125°C
TA = +25°C
TA = -40°C
LINEARITY vs. VSENSE
MAX9918 toc13
LINEARITY (%)
20100-10-20
-0.20
-0.15
-0.10
-0.05
0
0.05
0.10
0.15
0.20
0.25
-0.25
-30 30
VCM = -2V
VCC = 5V
VREFIN = VCC/2
AV = 90V/V
BIDIRECTIONAL
TA = -40°C
VSENSE (mV)
TA = +25°C
TA = +125°C
LINEARITY vs. VSENSE
MAX9918 toc15
LINEARITY (%)
706040 5020 30100 80
VCM = -2V
VCC = 5V
VREFIN = VGND
AV = 90V/V
UNIDIRECTIONAL
TA = -40°C
TA = +25°C
TA = +125°C
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
VSENSE (mV)
Maxim Integrated
│
9
www.maximintegrated.com
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
LINEARITY vs. VSENSE
MAX9918 toc16
VSENSE (mV)
LINEARITY (%)
65
6055
40 45 5010 15 20 25 30 35
5
-0.08
0.02
0.04
0.06
0
-0.02
-0.04
-0.06
0.08
0.10
0.12
0.14
0.16
0.18
0.20
-0.10
0 70
VCM = +14V
VCC = 5V
VREFIN = VGND
AV = 90V/V
UNIDIRECTIONAL
TA = -40°C
TA = +25°C
TA = +125°C
LINEARITY vs. VSENSE
MAX9918 toc18
VSENSE (mV)
LINEARITY (%)
80600 20 40
-60 -40 -20-80-100 100
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.10
-0.10
VCM = +14V
VCC = 5V
VREFIN = VCC/2
AV = 30V/V
BIDIRECTIONAL
TA = +25°C
TA = +125°C
TA = -40°C
VOUT - VREFIN vs. VSENSE
MAX9918 toc20
VSENSE (mV)
VOUT - VREFIN (V)
30200 10-20 -10-30
-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
-3.0
-40 40
MAX9918, VREFIN = VCC/2
BIDIRECTIONAL,
GAIN = 90V/V
-2V VCM: SOLID LINE
14V VCM: DASHED LINE
LINEARITY vs. VSENSE
MAX9918 toc17
VSENSE (mV)
LINEARITY (%)
80600 20 40
-60 -40 -20-80
-0.20
-0.15
-0.10
-0.05
0
0.05
0.10
0.15
0.20
0.25
-0.25
-100 100
VCM = -2V
VCC = 5V
VREFIN = VCC/2
AV = 30V/V
BIDIRECTIONAL
TA = +25°C
TA = +125°C TA = -40°C
VOUT - VREFIN vs. VSENSE
MAX9918 toc19
VOUT - VREFIN (V)
706040 500 10 20 30-10
-0.5
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
-1.0
-20 80
MAX9918, VREFIN = 0V
UNIDIRECTIONAL,
GAIN = 90V/V
-2V VCM: SOLID LINE
14V VCM: DASHED LINE
VSENSE (mV)
VOH/VOL vs. IOH
MAX9918 toc21
IOH (mA)
VOH AND VOL (mV)
987654321
50
100
150
200
250
300
350
0
0 10
VCC - VOH
VCM = +14V
VOL
Maxim Integrated
│
10
www.maximintegrated.com
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
ICC vs.VCM
MAX9918 toc23
VCM (V)
ICC (mA)
706040 500 10 20 30-10
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
0.4
-20 80
TA = +125°C
TA = +25°C TA = -40°C
VSENSE = 0V (DASH)
VSENSE + 50mV (SOLID)
IBIAS vs. VCM
MAX9918 toc24
VCM (V)
IBAIS (µA)
706040 500 10 20 30-10
-80
-60
-40
-20
0
20
40
60
80
100
-100
-20 80
MAX9918
VCC = 5V
INPUT LEAKAGE CURRENT vs. VCM
MAX9918 toc25
VCM (V)
INPUT LEAKAGE CURRENT (
µA)
6040200
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
5
10
15
20
-50
-20 80
IN+ - IN- = 50mV
VCC = VSHDN = 0V
VREFIN = 0V
TA = +125°C
TA = +25°C
TA = -40°C
DIFFERENTIAL RIN vs. VCM
MAX9918 toc26
VCM (V)
DIFFERENTIAL RIN (Ω)
55402510-5
100
200
300
400
500
600
700
800
900
1000
0
-20 70
GAIN vs. FREQUENCY
MAX9918 toc27
FREQUENCY (MHz)
GAIN (dB)
10.10.01
-30
-20
-10
0
10
20
30
40
50
-40
0.001 10
MAX9918
VCM = 14V
GAIN = 90V/V
GAIN vs. FREQUENCY
MAX9918 toc28
FREQUENCY (MHz)
GAIN (dB)
10.10.01
-50
-40
-30
-20
-10
0
10
20
30
40
-60
0.001 10
MAX9920
VCM = 14V
GAIN = 20V/V
ICC vs. VCC
MAX9918 toc22
VCC (V)
ICC (mA)
5.45.35.1 5.24.7 4.8 4.9 5.04.6
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0
4.5 5.5
VCM = 14V
VSENSE = 0V
VCM = -2V
GAIN vs. FREQUENCY
MAX9918 toc29
FREQUENCY (MHz)
GAIN (dB)
1010.10.01
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10
-100
0.001 100
MAX9918
VCM = 14V
GAIN = 90V/V
VCM = -2V
VCM = 14V
PSRR vs. FREQUENCY
MAX9918 toc30
FREQUENCY (kHz)
PSRR (dB)
1k1001010.10.010.001
-120
-100
-80
-60
-40
-20
0
-140
0.0001 10k
MAX9918
VCM = 14V
VSENSE = 50mV
Maxim Integrated
│
11
www.maximintegrated.com
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
SMALL-SIGNAL TRANSIENT
(GAIN = 45V/V)
MAX9918 toc31
50mV/div
10µs/div
5mV/div
MAX9918, VCM = 14V
VSENSE = 10mV TO 15mV
LARGE-SIGNAL TRANSIENT
(GAIN = 45V/V)
MAX9918 toc33
500mV/div
10µs/div
50mV/div
MAX9918, VCM = 14V
VSENSE = 0V TO 50mV
COMMON-MODE STEP RESPONSE
MAX9918 toc35
1V/div
10µs/div
10V/div
MAX9918, VCM = 14V
SSENSE = PS (50mV)
SMALL-SIGNAL TRANSIENT
(GAIN = 90V/V)
MAX9918 toc32
100mV/div
10µs/div
5mV/div
MAX9918, VCM = 14V
VSENSE = 10mV TO 15mV
LARGE-SIGNAL TRANSIENT
(GAIN = 90V/V)
MAX9918 toc34
1V/div
10µs/div
50mV/div
MAX9918, VCM = 14V
VSENSE = 0 TO 50mV
OUTPUT RESPONSE TO
COMMON-MODE TRANSIENT
MAX9918 toc36
VOUT
100mV/div
VCM
50V/div
0
4µs/div
OUTPUT AC-COUPLED
FULL SCALE
AT THE INPUT
Maxim Integrated
│
12
www.maximintegrated.com
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
(VCC = 5V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
SHUTDOWN ON/OFF DELAY
MAX9918 toc37
1V/div
4µs/div
5V/div
MAX9918, VCM = 14V
VSENSE = PS (50mV)
OUTPUT OVERDRIVE
RECOVERY (30V/V)
MAX9918 toc39
2V/div
4µs/div
200mV/div
MAX9918, VCM = 14V
VSENSE = 2 x PS
POWER-UP TIME
MAX9918 toc38
2V/div
4µs/div
5V/div
MAX9918, VCM = 14V
VSENSE = PS (50mV)
OUTPUT OVERDRIVE
RECOVERY (90V/V)
MAX9918 toc40
2V/div
4µs/div
50mV/div
MAX9918, VCM = 14V
VSENSE = 2 x PS
Maxim Integrated
│
13
www.maximintegrated.com
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
Detailed Description
The MAX9918/MAX9919/MAX9920 are single-supply,
high-accuracy uni-/bidirectional current-sense amplifi-
ers with a high common-mode input range that extends
from -20V to +75V. The MAX9918/MAX9919/MAX9920’s
input stage utilizes a pair of level shifters allowing a wide
common-mode operating range when measuring the volt-
age drop (VSENSE) across the current-sense resistor. The
first level shifter accommodates the upper common-mode
operating range from +2V to +75V. When the common-
mode voltage falls below +2V, the second level shifter is
used to accommodate negative voltages down to -20V.
The level shifters translate VSENSE to an internal refer-
ence voltage where it is then amplified with an instrumen-
tation amplifier. The instrumentation amplifier configura-
tion provides high precision with input offset voltages of
400µV (max). Indirect feedback of the instrumentation
amplifier allows the gain to be adjusted with an external
resistive-divider network on the MAX9918/MAX9920.
The MAX9919 is a fixed gain device available with laser-
trimmed resistors for gains of 45V/V (MAX9919F) and
90V/V (MAX9919N).
The MAX9918/MAX9919 operate with a full-scale sense
voltage of 50mV. The input stage of the MAX9920 pro-
vides an attenuation factor of 4, enabling a full-scale
sense voltage of 200mV.
Pin Description
8 SO-EP
TOP VIEW
MAX9918
MAX9919
MAX9920 FB
OUT
8
7
VCC
REFIN
6
5
GND
1
2RS-
SHDN
RS+
3
4EP*
+
*EXPOSED PAD. CONNECT EP TO SOLID GROUND FOR
PROPER THERMAL AND ELECTRICAL PERFORMANCE.
Pin Conguration
PIN NAME FUNCTION
1 RS+ Positive Current-Sensing Input. Power side connects to external sense resistor.
2 RS- Negative Current-Sensing Input. Load side connects to external sense resistor.
3 SHDN Active-High Shutdown Input. Connect to GND for normal operation.
4 GND Ground
5 OUT Current-Sense Output. VOUT is proportional to VSENSE.
6 FB
Feedback Input. Connect FB to a resistive-divider network to set the gain for the MAX9918 and
MAX9920. See the Adjustable Gain (MAX9918/MAX9920) section for more information. Leave FB
unconnected for the MAX9919 for proper operation.
7 REFIN Reference Input. Set REFIN to VCC/2 for bidirectional operation. Set REFIN to GND for
unidirectional operation.
8 VCC 5V Supply Voltage Input. Bypass VCC to GND with 0.1µF capacitor.
—EP Exposed Pad. Connect to a large-area contiguous ground plane for improved power dissipation.
Do not use as the only ground connection for the part.
www.maximintegrated.com Maxim Integrated
│
14
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
Uni-/Bidirectional Operation
The MAX9918/MAX9919/MAX9920 support both unidi-
rectional and bidirectional operation. The devices operate
in unidirectional mode with VREFIN = VGND. The output
is then referenced to ground and the output voltage VOUT
is proportional to the positive voltage drop (VSENSE) from
RS+ to RS- (Figure 1).
The MAX9918/MAX9919 operate in bidirectional mode
by application of a low-source impedance reference volt-
age in the 0V to VCC - 1.9V range, (typically VCC/2), to
REFIN. For the MAX9920, the reference voltage range
is 0V to VCC - 2.4V (typically VCC/2). The output volt-
age VOUT relative to VREFIN is then proportional to the
±VSENSE voltage drop from RS+ to RS- (Figure 2).
Figure 1. Unidirectional Operation
Figure 2. Bidirectional Operation
IDISCHARGE RSENSE
LOAD
TO ADC
VCC
GND
RS+ RS-
REFIN
OUT
40mV10mV 30mV20mV
0
DISCHARGE
CURRENT
0.9V
3.6V
2.7V
G = 90V/V
5V
1.8V
SHDN
VSENSE
VOUT
MAX9919N
IDISCHARGE RSENSE
ICHARGE
LOAD
TO ADC
2.5V
VCC
GND
RS+ RS-
REFIN
OUT -20mV 10mV 20mV
0
DISCHARGE
CURRENT
CHARGE
CURRENT
-1.8V
1.8V
0.9V
G = 90V/V
VSENSE
5V
-0.9V
-10mV
SHDN
VOUT - VREFIN
MAX9919N
www.maximintegrated.com Maxim Integrated
│
15
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
Shutdown Mode
Drive SHDN high to enter low-power shutdown mode. In
shutdown mode, the MAX9918/MAX9919/MAX9920 draw
0.5µA (typ) of quiescent current.
Adjustable Gain (MAX9918/MAX9920)
The MAX9918/MAX9920 feature externally adjustable
gain set by a resistive-divider network circuit using resis-
tors R1 and R2 (see the Functional Diagram). The gain
frequency compensation is set for a minimum gain of
30V/V for the MAX9918 and 7.5V/V for the MAX9920.
The gain G for the MAX9918/MAX9920 is given by the
following equation:
R2
G 1 (for MAX9918)
R1
and
R2
1R1
G (for MAX9920)
4

= +




+




=


Applications Information
Component Selection
Ideally, the maximum load current develops the full-scale
sense voltage across the current-sense resistor. Choose
the gain needed to yield the maximum output voltage
required for the application:
VOUT = VSENSE x G
where VSENSE is the full-scale sense voltage, 50mV for
the MAX9918/MAX9919, or 200mV for the MAX9920 and
G is the gain of the device. G is externally adjustable for
the MAX9918/MAX9920. The MAX9919 has a fixed gain
version of 45V/V (MAX9919F) or 90V/V (MAX9919N).
In unidirectional applications (VREFIN = 0V), select the
gain of the MAX9918/MAX9920 to utilize the full output
range between GND and VCC. In bidirectional applica-
tions (VREFIN = VCC/2), select the gain to allow an output
voltage range of ±VCC/2. VOUT must be at least 100mV
from either rail to achieve the rated gain accuracy.
Sense Resistor, RSENSE
Choose RSENSE based on the following criteria:
Accuracy: A high RSENSE value allows lower currents
to be measured more accurately. This is because off-
sets become less significant when the sense voltage
is larger. In the linear region (100mV < VOUT < VCC
- 100mV), there are two components to accuracy: input
offset voltage (VOS) and gain error (GE). Use the linear
equation to calculate total error:
VOUT = (G ± GE) x (VSENSE ± VOS)
For best performance, select RSENSE to provide approxi-
mately 50mV (MAX9918/MAX9919) or 200mV (MAX9920)
of sense voltage for the full-scale current in each applica-
tion. Sense resistors of 5mΩ to 100mΩ are available with
1% accuracy or better.
E󰀩ciency and Power Dissipation
At high current levels, the I2R losses in RSENSE can be
significant. Take this into consideration when choosing the
resistor value and its power dissipation (wattage) rating.
Also, the sense resistor’s value might drift if it is allowed to
heat up excessively. The precision VOS of the MAX9918/
MAX9919/MAX9920 allows the use of small sense resis-
tors to reduce power dissipation and reduce hot spots.
Inductance: Keep inductance low if ISENSE has a large
high-frequency component by using resistors with low
inductance value.
Power-Supply Bypassing and Grounding
Bypass the MAX9918/MAX9919/MAX9920’s VCC to
ground with a 0.1µF capacitor. Grounding these devices
requires no special precautions; follow the same caution-
ary steps that apply to the rest of the system. High-current
systems can experience large voltage drops across a
ground plane, and this drop may add to or subtract from
VOUT. Using a differential measurement between OUT
and REFIN prevents this problem. For highest current-
measurement accuracy, use a single-point star ground.
Connect the exposed pad to a solid ground to ensure
optimal thermal performance.
www.maximintegrated.com Maxim Integrated
│
16
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
A
INPUT
INPUT STAGE/
LEVEL SHIFTER
FIXED GAIN
G = 45V/V OR 90V/V
VCC
RS+
RS-
FB
OUT
REFIN
R2
R1
GND
SHDN
MAX9919F
ILOAD
50mV (typ) RSENSE
A
INPUT
INPUT STAGE/
LEVEL SHIFTER
ADJUSTABLE GAIN
VCC
RS+
RS-
FB
OUT
REFIN
R2
R1
GND
SHDN
MAX9918
MAX9920
ILOAD
MAX9918
50mV (typ)
MAX9920
200mV (typ)
RSENSE
GAIN IS SET BY EXTERNAL RESISTORS, R1 AND R2
G = [1+(R2/R1)] FOR MAX9918
G = [1+(R2/R1)]/4 FOR MAX9920
Functional Diagram
Chip Information
PROCESS: BiCMOS
www.maximintegrated.com Maxim Integrated
│
17
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
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 PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 SO-EP S8E+14 21-0111 90-0151
www.maximintegrated.com Maxim Integrated
│
18
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 10/09 Initial release —
1 1/10 Updated Functional Diagram 16
2 12/10 Added automotive qualied part 1
3 6/11 Added MAX9920ASA/V+ to data sheet 1
4 7/11 Added automotive qualied parts for the MAX9919NASA/V+ and the MAX9920ASA/V+ 1
5 1/13 Added automotive qualied part for the MAX9919FASA/V+ 1
6 1/15 Updated Applications and Benets and Features section 1
7 1/17 Added Junction-to-Case Thermal Resistance specication to Package Thermal
Characteristics section 2
8 9/17 Added AEC-Q100 qualication statement to Benets and Features section 1
9 2/19 Updated Applications, Benets and Features, and added Package Information 1, 2
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 specications 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. © 2019 Maxim Integrated Products, Inc.
│
19
MAX9918/MAX9919/MAX9920 -20V to +75V Input Range,
Precision Uni-/Bidirectional,
Current-Sense Ampliers
For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https://www.maximintegrated.com/en/storefront/storefront.html.