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Bidirectional, On-The-Fly Programmable
Gain, Current-Sense Amplifier with Wide
Measurement Range

MAX49918

General Description

Benefits and Features

The MAX49918 is a high-precision current-sense
amplifier (CSA) with an I2C programmable gain option
from 10V/V to 200V/V in 8 steps. The multiple
programmable gain options offer maximum flexibility forthe user to change gain on-the-fly.

•

The IC operating input common-mode range from -5V to+70V, with protections that extend down to -6V and up
to +80V, thus providing protection against reversebattery and high-voltage spikes.
The low input offset of ±1μV (typ) and low gain error of±0.01% (typ) make this device best-suited for highprecision current measurements.
The IC operates from a supply voltage of +2.7V to +5.5V
with a typical quiescent supply at 0.7mA. The device
operates over the full -40°C to +125°C temperature
range.

•
•
•
•
•
•
•
•
•
•

Programmable Gain Options through I2C from 10V/V
to 200V/V (8 steps)±1μV (typ) Input Offset Voltage for REF1 = REF2 =VDD/2±5μV (typ) Input Offset Voltage for REF1 = VDD and
REF2 = GND at Gain = 20V/V±0.01% (typ) Gain Error-5V to +70V Input Voltage Range-6V to +80V Protective Immunity
70kHz, -3dB Bandwidth at Gain = 20V/V
145dB DC CMRR
Rail-to-Rail Output
3mm x 3mm, TDFN-10 Package-40°C to +125°C Temperature Range

Ordering Information appears at end of data sheet.

The IC features bidirectional current sensing and isoffered in a 3mm x 3mm, 10-pin TDFN package.

Applications
•
•
•
•
•
•

Monitoring Distinct Current Levels
Using the Same Current-Sense Resistors AcrossMultiple System Variants
Requires a Non-Typical Gain Value Due to Sense
Resistor Constraints
H-Bridge Motor and Solenoid Current Sensing
Battery Current Monitoring
High- and Low-Side Precision Current Sensing

19-101747; Rev 0; 9/23

© 2023 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners.

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Simplified Block Diagram
3.3V
SYSTEMPOWER
SUPPLY
VDD

MAX49918

MCU

RS+
RS-

OUT

LEVEL
SHIFTING

ADC

REF1
REF2
SYSTEMGAIN
SELECTION

GND

www.analog.com

SDA

SCL

I2C

A0

Analog Devices | 2

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Absolute Maximum Ratings
RS+ and RS- to GND ............................................. -6V to +80V

Continuous Current into Pins......................................... ±10mA

RS+ to RS- .......................................................................... ±2V

Continuous Power Dissipation (Multi Layer Board) (TA =+70°C, derate 24.4mW/°C above +70°C)................ 1951.2mW

VDD to GND .......................................................... -0.3V to +6V
OUT, REF1, REF2 to GND ....................... -0.3V to VDD + 0.3V

Operating Temperature Range....................... -40°C to +125°C
Storage Temperature Range .......................... -65°C to +150°C

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

Package Information
10 TDFN
Package CodeT1033+1C

Outline Number

21-0137

Land Pattern Number

90-0003

Thermal Resistance, Four-Layer Board:
Junction to Ambient (θJA)
Junction to Case Thermal Resistance (θJC)

41°C/W
9°C/W

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.

www.analog.com

Analog Devices | 3

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Electrical Characteristics(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = -40°C to+125°C, unless otherwise noted. Typical values are at TA = +25°C (Note 1))
PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

5.5

V

1

mA

POWER SUPPLY CHARACTERISTICS
VDD

Guaranteed by PSRR

Supply Current

IDD

No loads

0.7

Power-Up TimetPWR_UP

Output settles to 1%

200

Supply Voltage

2.7

µs

CURRENT-SENSE AMPLIFIER
DC CHARACTERISTICS
Input Protected
Common-Mode Range
Input Common-Mode
Range
Input Bias Current(Note 2)
Input Offset Current(Note 2)
Input Leakage Current(Note 2)

VCM_P
VCM

Guaranteed by CMRR

-6

+80

V

-5

+70

V

IRS+, IRS-

0.5

150

nA

IRS+ - IRS-

0.1

50

nA

1

200

nA

±1

±10

IRS+, IRS-

VDD = 0V,
VRS± = 70V
TA = +25°C
For all gain options

Input Offset Voltage

VOS
VREF1 = VDD,
VREF2 = GND

Input Offset Voltage
Drift (Note 2)
Power Supply Rejection
Ratio
Common-Mode
Rejection Ratio
Reference Voltage
Rejection Ratio
Input CapacitanceGain (Note 3)

Gain Switching Time
Gain Error

www.analog.com±50±5-40°C ≤ TA ≤

±40

μV

±80

+125°C

TCVOS

50

400

nV/°C

PSRR

2.7V ≤ VDD ≤ 5.5V; -40°C ≤ TA ≤ +125°C

95

125

dB

CMRR

-5V ≤ VCM ≤ +70V; -40°C ≤ TA ≤ +125°C

130

145

dB

RRRR

VREF = 1.5V to 2.5V; -40°C ≤ TA ≤+125°C

90

115

dB

CIN

RS+, RS- input

4.5

pF

I2C Programmable

10
20
40
50
80
100
160
200

V/V

25

µs

G

tGAIN
GE

Nonlinearity Error
Output Resistance-40°C ≤ TA ≤+125°CTA = +25°C

ROUT

Settle within 1% of the 1V final value
TA = +25°C±0.01

For all gain options±0.1%-40°C ≤ TA ≤+125°C
10mV ≤ VSENSE ≤ 100mV; G = 10V/V

0.01

%

VOUT = VDD/2, IOUT = ±500μA

0.3

Ω

±0.2

Analog Devices | 4

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = -40°C to+125°C, unless otherwise noted. Typical values are at TA = +25°C (Note 1))
PARAMETERSYMBOL

CONDITIONS

Output Voltage SwingHigh
Output Voltage Swing
Low
Output Voltage SwingHigh
Output Voltage Swing
Low
Output Short-Circuit
Current

VOH

Source 500μA

VOL

Sink 500μA

VOH

No LoadVOL

No Load

ISC

Shorted to either VDD or GND

MIN
VDD 0.015

TYP

MAX

UNITS
V

15
VDD 0.004

mV
V

4
55

mV
mA

AC CHARACTERISTICS

Signal Bandwidth

Output Slew Rate
AC Power Supply
Rejection Ratio
AC Common-Mode
Rejection Ratio
Capacitive Load
Stability
Input Voltage Noise
Density
Settling Time (Settling to
0.1%)

BW-3dBSR

G = 10V/V

VSENSE = 1VPP/G75

G = 20V/V

VSENSE = 1VPP/G70

G = 40V/V

VSENSE = 1VPP/G60

G = 50V/V

VSENSE = 1VPP/G55

G = 80V/V

VSENSE = 1VPP/G45

G = 100V/V

VSENSE = 1VPP/G40

G = 160V/V

VSENSE = 1VPP/G30

VSENSE = 1VPP/G
G =200V/V
2VPP output square wave, centered at
VDD/2

25

kHz

0.3

V/µs

AC PSRR

f = 200kHz, 100mVPP sine wave

35dB

AC CMRR

f = 200kHz, 100mVPP sine wave

60

dB

With 250Ω isolation resistor

20

nF

Without any isolation resistor

200

pF

en

At 1kHz

100

nV/Hz

tS

VSENSE steps from -50mV to 50mV

20

µs

CLOAD

I2C INTERFACE TIMING (400kHz I2C)SCL Clock Frequency

fSCL

400

kHz

START Hold TimetHD:STASTART Setup TimetSU:STA

600

ns

Clock Low Period

tLOW

1.3

µs

Clock High Period

tHIGH

600

ns
ns

600
90% of SCL to 90% of SDA

ns

Data Setup TimetSU:DAT

10% of SDA to 10% of SCL

100

Data Hold TimetHD:DAT

10% of SDA to 10% of SCL0

SCL Max Rise and FallTime
SDA Max Rise and Fall
Time
STOP Condition Setup
TimetR, tF300

ns

tR, tF300

ns

www.analog.com

tSU:STO

90% of SCL to 10% of SDA

600

900

ns

ns

Analog Devices | 5

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = -40°C to+125°C, unless otherwise noted. Typical values are at TA = +25°C (Note 1))
PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

DC LOGIC CHARACTERISTICS (SDA, SCL, A0)
Input Voltage High

VIH

Input Voltage Low

VIL

Output Voltage Low

VOL

Input Capacitance

CIN

% of
VDD

70
30
0.4
3

% of
VDD
V
pF

Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range and relevant supply
voltage range are guaranteed by design and characterization.
Note 2: Guaranteed by design and bench characterization.
Note 3: Gain is calculated based on two points measurements: VSENSE1 and VSENSE2. VSENSE1 = -1V/Gain and VSENSE2 =1V/Gain.

Typical Operating Characteristics(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 6

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 7

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 8

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 9

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 10

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 11

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 12

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range(VCM = VRS+ = VRS- = +50V, VDD = +3.3V, VSENSE = VRS+ - VRS- = 0V, VREF1 = VDD/2, VREF2 = VDD/2, G = 20V/V, TA = +25°C,
unless otherwise noted.)www.analog.com

Analog Devices | 13

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Pin Configurations

TOP VIEW

RS+

1

10

SDA

RS-

2

MAX49918

9

SCL

GND

3

EP

8

A0

OUT

4

7

REF1

VDD

5

56

REF2

+

TDFN-103mm x 3mm

Pin Descriptions
PIN

NAME

1

RS+

Positive Current-Sensing Input. Power side connects to external sense resistor.

FUNCTION

2

RS-

Negative Current-Sensing Input. Load side connects to external sense resistor.

3

GND

Ground. Should be connected to a solid ground plane for best performance.

4

OUT

Current-Sense Voltage Output. VOUT is proportional to VSENSE.

5

VDD

Supply Voltage Input. Bypass VDD to GND with a 0.1μF capacitor.

6

REF2

Reference 2 Input. REF2 and REF1 determine whether the device is used as uni or bidirectional.

7

REF1

Reference 1 Input. REF2 and REF1 determine whether the device is used as uni or bidirectional.

8

A0

I2C Address as explained in the Detailed Description section.

9SCL

I2C Clock.

10

SDA

I2C Data.

-

EP

Exposed Pad. Internally connected to GND.

Detailed Description
The MAX49918 is a high-precision current-sense amplifier (CSA) with an I2C programmable gain option from 10V/V to
200V/V in 8 steps. The multiple programmable gain options offer maximum flexibility for the user to change gain on-thefly.
The MAX49918 operating input common-mode ranges from -5V to +70V, with protections that extend down to -6V andup to +80V, thus providing protection against reverse-battery and high-voltage spikes.
The low input offset of ±1μV(typ) and low gain error of ±0.01%(typ) make the device well-suited for high-precision current
measurements.
The MAX49918 operates from a supply voltage of +2.7V to +5.5V, with a typical quiescent supply at 0.7mA.

www.analog.com

Analog Devices | 14

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Programmable Gain
The MAX49918 features a programmable gain through I2C. There are eight gain options with the following values in V/V:
10, 20, 40, 50, 80, 100, 160, and 200.

I2C Device Address
The MAX49918 uses an input pin (A0) that determines the least-significative bit (LSB) of the I2C device address word
below.
BIT 6
1

BIT 5
1

BIT 4
0

BIT 3
0

BIT 2
1

BIT 1
0

BIT 0
A0

I2C Gain register
The register address to set the gain is 0x00. And the data to set the gain is in the table below.
GAIN
DATA (Hex)

10
0

20
1

40
2

50
3

80
4

100
5

160
6

200
7

Application Information
Output Voltage
The MAX49918 has two reference inputs (REF1 and REF2) to set the device in either unidirectional or bidirectional
operation mode. Connect the REF1 and REF2 inputs to low-impedance voltage source(s) to set the MAX49918 output(VOUT) reference level. Do not connect REF1 and REF2 inputs to any voltages lower than GND or higher than VDD.
VREF is defined as the average voltage of VREF1 and VREF2, i.e., the output voltage refers to VREF = (VREF1 + VREF2)/2.
Use the following equation to set the gain:
VOUT = VSENSE x GAIN + VREF
Where VSENSE = VRS+ - VRS-, and GAIN is the voltage gain of the MAX49918.

Ground-Referenced Output
Connect REF1 and REF2 inputs together and to ground. In this mode, the output is referenced to ground, and the output
is taken to ground when the voltage drop across RSENSE is 0V. The output voltage then increases proportionally to thevoltage drop (VSENSE) from RS+ to RS-.

VDD-Referenced Output
Connect REF1 and REF2 inputs together and to VDD. In this mode, the output is referenced to VDD, or the output is taken
to VDD when the VSENSE is 0V. The input VSENSE must be negative to decrease the output voltage.

Setting Output to Mid-Supply Voltage
Connect REF1 to VDD and REF2 to ground. In this mode, it creates a ratio-metric offset to the supply voltage, whichmeans if VDD increases or decreases, the output remains at VDD/2 when there is no VSENSE. This configuration is usefulwhen external references are not available for offsetting the output.

Setting Output to Mid-External Reference
Connect one reference input pin to a reference voltage source and the other to ground. In this case, VOUT refers to theexternal reference voltage divided by 2.

Setting Output to External Reference
Connect both reference input pins together to a reference voltage, which creates an output voltage equal to the reference
voltage when the voltage drop across RSENSE is zero. The output decreases when the input VSENSE is negative. The
output increases when the input VSENSE is positive.

www.analog.com

Analog Devices | 15

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Ordering Information
PART NUMBER
MAX49918IATB+T

DIE TYPE

PACKAGEPACKAGE CODEOW05A-0A

TDFN-CUT1033+1C

T = Tape-and-reel.

www.analog.com

Analog Devices | 16

MAX49918

Bidirectional, On-The-Fly Programmable Gain,
Current-Sense Amplifier with Wide Measurement
Range

Revision History
REVISIONNUMBER
0

REVISION
DATE
9/23
Initial release

DESCRIPTIONPAGESCHANGED—

Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is
assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may
result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of theirrespective owners.

w w w . a n a l o g . c o mAnalog Devices | 17