MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
EVALUATION KIT AVAILABLE
19-5015; Rev 5; 1/13
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
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 moni-
toring 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 fea-
tures fixed gains of 45V/V (MAX9919F) and 90V/V
(MAX9919N). The MAX9918/MAX9919/MAX9920 oper-
ate 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 sin-
gle 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
4x4 Transmission Control
Electronic Throttle Control
Super-Capacitor Charge/Discharge Monitoring in
Hybrid Cars
Precision High-Voltage Current Monitoring
Features
o-20V to +75V Input Common-Mode Voltage Range
o400µV (max) Input Offset Voltage
o0.6% (max) Gain Accuracy Error
oUni- or Bidirectional Current Sensing
oReference Input for Bidirectional OUT
o120kHz, -3dB Bandwidth (MAX9919N)
oSingle-Supply Operation (4.5V to 5.5V)
o1mA Supply Current
o0.5µA (typ) Shutdown Current
oRail-to-Rail Output
o-40°C to +125°C Automotive Temperature Range
M
φ2B
φ1B
ADC
REF
A
INPUT STAGE
LEVEL SHIFTER
RSENSE
VBATT
ADJUSTABLE GAIN
VCC VCC
RS+
RS-
FB
OUT
REFIN
R2
R1
GND
GND
SHDN
φ2B
φ1A 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*
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.
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
2Maxim Integrated
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(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 val-
ues are at TA= +25°C.) (Note 1)
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.
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
PACKAGE THERMAL CHARACTERISTICS (Note 1)
SO-EP
Junction-to-Ambient Thermal Resistance (θJA) ...........41°C/W
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = +25°C ±0.14 ±0.4
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = -40°C
to +125°C ±0.7
TA = +25°C ±0.08 ±0.4
MAX9918
VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C
to +125°C ±1.3
TA = +25°C ±0.18 ±0.4
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = -40°C
to +125°C ±0.9
TA = +25°C ±0.11 ±0.4
MAX9919_
VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C
to +125°C ±1.0
TA = +25°C ±0.48 ±1.2
VRS+ = VRS- =
+14V, VREFIN
= 0V
TA = -40°C
to +125°C ±3.0
TA = +25°C ±0.10 ±0.9
Input Offset Voltage (Note 2) VOS
MAX9920
VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C
to +125°C ±3.5
mV
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.
**
As per JEDEC51 Standard (multilayer board).
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
3
Maxim Integrated
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
VRS+ = VRS- = +14V ±1.2
MAX9918 VRS+ = VRS- = -2V ±3.3
VRS+ = VRS- = +14V ±1.8
MAX9919_ VRS+ = VRS- = -2V ±1.8
VRS+ = VRS- = +14V ±2.4
Input Offset Voltage Drift
(Note 3) VOSD
MAX9920 VRS+ = VRS- = -2V ±8.8
μV/°C
Common-Mode Range VCM Inferred from CMRR tests -20 +75 V
-2V ≤ VCM ≤ +14V 80
M AX 9918, M AX 9919 -20V ≤ VCM ≤ +75V 96
-2V ≤ VCM ≤ +14V 72
Common-Mode Rejection Ratio
(Note 3) CMRR
MAX9920 -20V ≤ VCM ≤ +75V 86
dB
TA = +25°C ±175
Input Bias Current IRS+, IRS- -20V ≤ VCM ≤ +75V TA = -40°C to +125°C ±250 μA
Input Offset 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
Common mode 300 kΩ
MAX9918,
MAX9919_ Differential 715 Ω
Common mode 330 kΩ
Input Resistance
MAX9920 Differential 224 Ω
MAX9918, MAX9919_ 50
Full-Scale Sense Voltage (Note 4) VSENSE Inferred from gain
error test MAX9920 200 mV
MAX9918, MAX9920 Adj
MAX9919F 45Gain (Notes 2, 4) G
MAX9919N 90
V/V
MAX9918 30
Minimum Adjustable Gain GADJ MAX9920 7.5 V/V
ELECTRICAL CHARACTERISTICS (continued)
(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 val-
ues are at TA= +25°C.) (Note 1)
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
4Maxim Integrated
ELECTRICAL CHARACTERISTICS (continued)
(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 val-
ues are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = +25°C,
VREFIN = 0V ±0.08 ±0.6
VRS+ = VRS- =
+14V TA = -40°C to
+125°C,
VREFIN = 0V
±1.2
TA = +25°C ±0.02 ±0.6
MAX9918
VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C to
+125°C ±1.0
TA = +25°C ±0.13 ±0.45
VRS+ = VRS- =
+14V, VREFIN =
0V
TA = -40°C to
+125°C ±1.2
TA = +25°C ±0.10 ±0.45
MAX9919F VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C to
+125°C ±0.9
TA = +25°C ±0.16 ±0.6
VRS+ = VRS- =
+14V, VREFIN =
0V
TA = -40°C to
+125°C ±1.2
TA = +25°C ±0.11 ±0.6
MAX9919N VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C to
+125°C ±1.0
TA = +25°C ±0.29 ±1.0
VRS+ = VRS- =
+14V, VREFIN =
0V
TA = -40°C to
+125°C ±1.7
TA = +25°C ±0.24 ±1.0
Gain Error
(Note 2) GE
MAX9920 VRS+ = VRS- =
-2V, VREFIN =
0V
TA = -40°C to
+125°C ±1.7
%
FB Input Bias Current IFB MAX9918, MAX9920 5 15 nA
RL = 100kΩ to GND 3 10
Output-Voltage High (Note 4) VCC - VOH
VSENSE = 200mV for
MAX9918, MAX9919_,
VSENSE = 400mV for
MAX9920 RL = 10kΩ to GND 12 40
mV
RL = 100kΩ to VCC 310
Output-Voltage Low (Note 4) VOL
VSENSE = -200mV for
MAX9918, MAX9919_,
VSENSE = -400mV for
MAX9920 RL = 10kΩ to VCC 10 40
mV
OUT shorted to VCC 44
Short-Circuit Current ISC OUT shorted to GND 41 mA
Output Resistance ROUT 0.1 Ω
M AX 9918, M AX9919_ 0 VCC
/2
VCC -
1.9
REFIN Voltage Range Inferred from REFIN
CMRR test MAX9920 0 VCC
/2
VCC -
2.4
V
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
5
Maxim Integrated
ELECTRICAL CHARACTERISTICS (continued)
(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 val-
ues are at TA= +25°C.) (Note 1)
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX9918, MAX9919_ 0V ≤ VREFIN ≤ (VCC
- 1.9V) 82 103
REFIN Common-Mode Rejection
Ratio RE FIN
C M R R
MAX9920 0V ≤ VREFIN ≤ (VCC
- 2.4V) 75 90
dB
M AX 9918, M AX 9919_, V
RS +
= V
RS -
= ± 50m V ±100
REFIN Current IREFIN MAX9920, VRS+ = VRS- = ±200mV ±100 μA
SHDN Logic-High VIH 2.0 V
SHDN Logic-Low VIL 0.8 V
SHDN Logic Input Current 0 ≤ VSHDN ≤ VCC 5μA
Supply Voltage Range VCC Inferred from PSRR test 4.5 5.5 V
MAX9918, MAX9919_ 4.5V ≤ VCC ≤ 5.5V 74 103
Power-Supply Rejection Ratio
(Note 3) PSRR MAX9920 4.5V ≤ VCC ≤ 5.5V 68 100 dB
TA = +25°C 0.7 1.2
VRS+ = VRS- = +14V TA = - 40°C to + 125°C 1.5
TA = +25°C 1.0 1.6
Supply Current ICC
VRS+ = VRS- = -2V TA = - 40°C to + 125°C 2.2
mA
Shutdown Supply Current ICC_SHDN VSHDN = VCC = 5V 0.5 10 μA
MAX9918, VSENSE = 50mV 75
MAX9919F, VSENSE = 50mV 250
MAX9919N, VSENSE = 50mV 120
Small Signal -3dB Bandwidth BW
MAX9920, VSENSE = 200mV 230
kHz
MAX9918 0.6
MAX9919F 0.9
MAX9919N 3.0
Slew Rate SR
MAX9920 1.5
V/μs
VSENSE = 5mV to 50mV step 12
MAX9918 VSENSE = 50mV to 5mV step 7
VSENSE = 5mV to 50mV step 3.5
MAX9919F VSENSE = 50mV to 5mV step 2.5
VSENSE = 5mV to 50mV step 3.5
MAX9919N VSENSE = 50mV to 5mV step 3
V
S E N S E
= 20m V to 200m V step 5
1% Settling Time from VSENSE
Step
MAX9920 V
S E N S E
= 200m V to 20m V step 3
μs
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
6Maxim Integrated
ELECTRICAL CHARACTERISTICS (continued)
(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 val-
ues are at TA= +25°C.) (Note 1)
PARAMETERS SYMBOL CONDITIONS MIN TYP MAX UNITS
VCM = -2V to +14V step 2.5
MAX9918,
VSENSE = 50mV VCM = +14V to -2V step 0.5
VCM = -2V to +14V step 2.5
MAX9919F,
VSENSE = 50mV VCM = +14V to -2V step 0.5
VCM = -2V to +14V step 3.5
MAX9919N,
VSENSE = 50mV VCM = +14V to -2V step 3.5
VCM = -2V to +14V step 0.25
1% Settling Time from VCM Step
MAX9920,
VSENSE = 200mV VCM = +14V to -2V step 2.5
μs
MAX9918, VSENSE = 50mV, 1% settling 4.5
MAX9919F, VSENSE = 50mV, 1% settling 5
MAX9919N, VSENSE = 50mV, 1% settling 6
Power-Up Time
MAX9920, VSENSE = 200mV, 1% settling 5
μs
Max Capacitive Load Stability No sustained oscillations (Note 5) 50 pF
MAX9918, MAX9919_ 60
Input-Referred Noise Voltage
Density en10kHz MAX9920 174 nV/√Hz
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.
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
7
Maxim Integrated
Typical Operating Characteristics
(VCC = 5V, TA= +25°C, unless otherwise noted.)
VOS
(VRS+ = +14V)
MAX9918 toc01
OFFSET VOLTAGE (FV)
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
VOS DRIFT
(VRS+ = +14V)
MAX9918 toc02
OFFSET VOLTAGE (FV/°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 (FV)
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 (FV/°C)
N (%)
846-6 -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
VCM (V)
VOS (uV)
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
VCC (V)
VOS (FV)
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
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
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
8Maxim Integrated
Typical Operating Characteristics (continued)
(VCC = 5V, TA= +25°C, unless otherwise noted.)
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. 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 = +125NC
TA = +25NC
TA = -40NC
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 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 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)
LINEARITY vs. VSENSE
MAX9918 toc15
LINEARITY (%)
706040 5020 3010080
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)
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
9
Maxim Integrated
Typical Operating Characteristics (continued)
(VCC = 5V, TA= +25°C, unless otherwise noted.)
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)
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
VOH/VOL vs. IOH
MAX9918 toc21
IOH (mA)
VOH AND VOL (mV)
987654321
50
100
150
200
250
300
350
0
010
VCC - VOH
VCM = +14V
VOL
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
070
VCM = +14V
VCC = 5V
VREFIN = VGND
AV = 90V/V
UNIDIRECTIONAL
TA = -40°C
TA = +25°C
TA = +125°C
LINEARITY vs. VSENSE
MAX9918 toc17
VSENSE (mV)
LINEARITY (%)
806002040
-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
LINEARITY vs. VSENSE
MAX9918 toc18
VSENSE (mV)
LINEARITY (%)
806002040
-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
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
10 Maxim Integrated
Typical Operating Characteristics (continued)
(VCC = 5V, TA= +25°C, unless otherwise noted.)
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
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 = +125NC
TA = +25NCTA = -40NC
VSENSE = 0V (DASH)
VSENSE + 50mV (SOLID)
IBIAS vs. VCM
MAX9918 toc24
VCM (V)
IBAIS (FA)
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 (FA)
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 = +125NC
TA = +25NC
TA = -40NC
DIFFERENTIAL RIN vs. VCM
MAX9918 toc26
VCM (V)
DIFFERENTIAL RIN (I)
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
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
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
11
Maxim Integrated
Typical Operating Characteristics (continued)
(VCC = 5V, TA= +25°C, unless otherwise noted.)
SMALL-SIGNAL TRANSIENT
(GAIN = 45V/V)
MAX9918 toc31
50mV/div
10Fs/div
5mV/div
MAX9918, VCM = 14V
VSENSE = 10mV TO 15mV
SMALL-SIGNAL TRANSIENT
(GAIN = 90V/V)
MAX9918 toc32
100mV/div
10Fs/div
5mV/div
MAX9918, VCM = 14V
VSENSE = 10mV TO 15mV
LARGE-SIGNAL TRANSIENT
(GAIN = 45V/V)
MAX9918 toc33
500mV/div
10Fs/div
50mV/div
MAX9918, VCM = 14V
VSENSE = 0V TO 50mV
LARGE-SIGNAL TRANSIENT
(GAIN = 90V/V)
MAX9918 toc34
1V/div
10Fs/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
COMMON-MODE STEP RESPONSE
MAX9918 toc35
1V/div
10Fs/div
10V/div
MAX9918, VCM = 14V
SSENSE = PS (50mV)
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
12 Maxim Integrated
Typical Operating Characteristics (continued)
(VCC = 5V, TA= +25°C, unless otherwise noted.)
SHUTDOWN ON/OFF DELAY
MAX9918 toc37
1V/div
4Fs/div
5V/div
MAX9918, VCM = 14V
VSENSE = PS (50mV)
OUTPUT OVERDRIVE
RECOVERY (30V/V)
MAX9918 toc39
2V/div
4Fs/div
200mV/div
MAX9918, VCM = 14V
VSENSE = 2 x PS
POWER-UP TIME
MAX9918 toc38
2V/div
4Fs/div
5V/div
MAX9918, VCM = 14V
VSENSE = PS (50mV)
OUTPUT OVERDRIVE
RECOVERY (90V/V)
MAX9918 toc40
2V/div
4Fs/div
50mV/div
MAX9918, VCM = 14V
VSENSE = 2 x PS
Detailed Description
The MAX9918/MAX9919/MAX9920 are single-supply,
high-accuracy uni-/bidirectional current-sense amplifiers
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
voltage 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 instru-
mentation amplifier. The instrumentation amplifier
configuration 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.
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
13
Maxim Integrated
Pin Description
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.
6FB
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.
8V
CC 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.
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 Configuration
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
14 Maxim Integrated
Uni-/Bidirectional Operation
The MAX9918/MAX9919/MAX9920 support both unidi-
rectional and bidirectional operation. The devices oper-
ate in unidirectional mode with VREFIN = VGND. The
output is then referenced to ground and the output volt-
age 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
voltage 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 voltage
VOUT relative to VREFIN is then proportional to the
±VSENSE voltage drop from RS+ to RS- (Figure 2).
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
MAX9919N
VSENSE
VOUT
Figure 1. Unidirectional Operation
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
Figure 2. Bidirectional Operation
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
15
Maxim Integrated
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
resistors 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:
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, R
SENSE
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 ±V
OS)
For best performance, select RSENSE to provide
approximately 50mV (MAX9918/MAX9919) or 200mV
(MAX9920) of sense voltage for the full-scale current in
each application. Sense resistors of 5mΩto 100mΩare
available with 1% accuracy or better.
Efficiency 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 resistors 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 cautionary steps that apply to the rest of the sys-
tem. High-current systems can experience large volt-
age drops across a ground plane, and this drop may
add to or subtract from VOUT. Using a differential mea-
surement between OUT and REFIN prevents this prob-
lem. For highest current-measurement accuracy, use a
single-point star ground. Connect the exposed pad to a
solid ground to ensure optimal thermal performance.
(G R
Rf=+
⎛
⎝
⎜⎞
⎠
⎟
12
1oor MAX
and
G
9918
1
)
=
++
⎛
⎝
⎜⎞
⎠
⎟
⎛
⎝
⎜
⎜
⎜
⎜
⎞
⎠
⎟
⎟
⎟
⎟
R
Rfor MAX
2
1
49920()
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
16 Maxim Integrated
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
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
17
Maxim Integrated
PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.
8 SO-EP S8E+14 21-0111 90-0151
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.
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.
18
________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2013 Maxim Integrated Products, Inc. Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
MAX9918/MAX9919/MAX9920
-20V to +75V Input Range, Precision
Uni-/Bidirectional, Current-Sense Amplifiers
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 qualified part 1
3 6/11 Added MAX9920ASA/V+ to data sheet 1
4 7/11 Added automotive qualified parts for the MAX9919NASA/V+ and the MAX9920ASA/V+ 1
5 1/13 Added automotive qualified part for the MAX9919FASA/V+ 1
