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Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

MAX49925

General Description

Benefits and Features

The MAX49925 is a bidirectional current-sense
amplifier (CSA) with an input common-mode rangethat extends from -40V to +76V, making it suitable for
48V HEV applications where there are large
automotive transients.

•This CSA has an extended input protection range of-42V to +80V against reverse-battery and highvoltage spikes. The wider input protection range also
helps relax TVS requirements, leading to lower BOM
cost and reduced component size.
The MAX49925 is well-suited for phase-current
monitoring of inductive loads, such as motors andsolenoids, where pulse-width modulation (PWM) is
used to control the drive voltage and current.
The MAX49925 uses an improved technique to help
reject common-mode input PWM edges with slew
rates up to and beyond 500V/μs.

•••••••••••

Fast, 500ns PWM Edge Recovery from >500V/µs
PWM Edges
140dB DC CMRR Rejection-40V to +76V Input Voltage Range-42V to +80V Protective Immunity
300kHz, -3dB Bandwidth

On-the-fly Programmable Gain with two input pins:
10V/V, 20V/V, 50V/V, 100V/V
5μV (typ) Input Offset Voltage±0.3% (max) Gain Error
Rail-to-Rail Output
3mm x 3mm, 10-Pin TDFN with Side-WettableFlanks-40°C to +125°C Temperature Range, Automotive
Grade 2AEC-Q100 Qualified

Ordering Information appears at end of data sheet.

The MAX49925 operates over the full -40°C to+125°C temperature range and runs from a supply
voltage of +2.7V to +5.5V. It is available in a 3mm x3mm, 10-pin TDFN package with side-wettableflanks.

Applications
••
•
•••
•

PWM H-Bridge Motor In-Line/In-Phase/Winding
Current Sensing
Solenoid Current Sensing
Current Monitoring of Inductive Loads
Battery Stack Monitors
High-Power DC Motors
Automotive
48V Hybrid and Electric Vehicles (HEV)

19-101605; Rev 2; 7/23

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

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

Simplified Block Diagram
VDD
RY
RP

RX

RS+RS-RF

PWM
REJE CT

OUT

RP
RXRY
RF
REF1
REF2
GAIN
SELE CTION

MAX49925
GAIN1

GND

GAIN2

Absolute Maximum Ratings
RS+ and RS- to GND .......................................... -42V to +80V

Continuous Current in OUT ............................................. 10mA

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

Continuous Current in RS+ and RS- ............................... 10mA

VDD to GND ......................................................... -0.3V to +6V

Continuous Power Dissipation (Multilayer Board) (TA = +70°C,derate 24.4mW/°C above +70°C).......................... 1951.20mW

REF1, REF2, GAIN1, GAIN2, OUT to GND-0.3V to VDD +0.3V
Continuous Current in REF1, REF2, GAIN1, GAIN2 ...... 10mA

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 abs olute maximum rating conditions for extended periods may affectdevice reliability.

Package Information
10 TDFN
Package CodeOutline Number
Land Pattern Number
Thermal Resistance, Four-Layer Board:
Junction to Ambient (θ JA)
Junction to Case (θ JC)

T1033Y+1C
21-100346
90-0003

T1033+1C
21-0137

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 | 2

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

Electrical Characteristics(VDD = 3.3V, VCM = 48V, VSENSE = 800mV/gain, V REF1 = VDD/2, VREF2 = VDD/2, OUT Loading = 10kΩ and 20pF to GND, T MIN = 40°C, TMAX = +125°C)
PARAMETERSYMBOL

CONDITIONS

MIN

TYP

MAXUNITS

5.5V

7mA

POWER SUPPLY CHARACTERISTICS
Supply Voltage

VDD

Supply Current

IDD

Power-Up TimetPWR_UP

Guaranteed by PSRR

2.75Out settle within 1%

200µs

CURRENT-SENSE AMPLIFIER—DC CHARACTERISTICS
Input-Protected
Common-Mode Range
Input Common-ModeRange

VCM_P

Input Bias Current

IRS+, IRS-

Input Leakage Current

VCM

ILKG

Input Offset Voltage

VOS

Input Offset Drift

TCVOS

Power Supply Rejection
Ratio
Common-Mode
Rejection Ratio
Input CapacitanceNominal Gain

PSRR
CMRRCIN

G-40°C ≤ TA ≤ +125°C-42+80V-40+76V

VSENSE = 0V (Note 1)

3300nAVSENSE = 20mV

3.56µAVDD = 0V, 0V ≤ VRS± ≤ 65V (Note 1)

3400nATA = +25°C

5-40°C ≤ TA ≤ +125°C

20200

μV

0.05

µV/°C

90110dB

120140dB

RS+ and RS- input

3pF

GAIN1 = GND, GAIN2 = GND

10GAIN1 = VDD, GAIN2 = GND

20GAIN1 = GND, GAIN2 = V DD

50GAIN1 = VDD, GAIN2 = VDD

1000.05

0.3%

2.7V ≤ VDD ≤ 5.5V-40V ≤ VCM ≤ +76V; -40°C ≤ TA ≤+125°C

V/VGain Error

GE-40°C ≤ TA ≤ +125°C, -800mV/gain ≤VSENSE ≤ 800mV/gain

Output Voltage Swing
HighOutput Voltage Swing
Low
Output Short-Circuit
Current
Reference Voltage
Rejection Ratio

VOHSourcing 5mA; VOH = VDD - VOUT

45100mVVOL

Sinking 5mA; VOL = VOUT - GND

3570mV

ISC

Shorted to either VDD or GND

20mA

2µV/V

300

kHz

1.5V/µs±200mV output step

2.5µstS_PWM

0 to 50V edges: 500V/μs rise/fall times,
VSENSE = 0mV (VRS+ = VRS-)

500ns

AC CMRR

100mVAC sine, f = 100kHz

60dB

RRRR

CURRENT SENSE AMPLIFIER—AC CHARACTERISTICS
Signal Bandwidth

BW-3dB

Output Slew Rate

SRAmplifier Small-Signal
Settling Time (1%)
PWM Edge Recovery
Settling TimeAC Common-Mode
Rejection RatiotS

www.analog.com

2VP-P output square wave, centered at
1.65VAnalog Devices | 3

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection(VDD = 3.3V, VCM = 48V, VSENSE = 800mV/gain, V REF1 = VDD/2, VREF2 = VDD/2, OUT Loading = 10kΩ and 20pF to GND, T MIN = 40°C, TMAX = +125°C)
PARAMETERAC Power Supply
Rejection Ratio
Voltage Noise Density

SYMBOL

CONDITIONSAC PSRR

100mVAC sine, f = 100kHz

60dB

At 10kHz150nV/√Hz

enMIN

TYP

MAXUNITSCURRENT SENSE AMPLIFIER—LOGIC INPUT DC CHARACTERISTICS
Input Low Level

VIL

Input High Level

VIH

Input Leakage Current

IL

0.55
1.3

VV

330nA

Note 1: Limits are 100% tested at TA = +25°C. Limits over the operating temperature range and relevant supply voltage range areguaranteed by design and characterization.

Typical Operating Characteristics(VDD = 3.3V, VSENSE = 800mV/gain, VCM = 48V, OUT load = 10kΩ and 20pF to GND, T A = +25°C, unless otherwise noted.)www.analog.com

Analog Devices | 4

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejectionwww.analog.com

Analog Devices | 5

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejectionwww.analog.com

Analog Devices | 6MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

Pin Configurations

TOP VIEW

RS+1RS-210GAIN19GAIN28REF1

MAX49925
N.C.

3EPOUT

47REF2GND

56VDD

10 TDFN
3mm x 3mm

Pin Descriptions
PIN

NAME

1RS+

External Resistor Power-Side Connection Input

2RS-

External Resistor Load-Side Connection Input

3N.C.

Not Connected

4OUT

Current-Sense Output. Output has its common-mode point at VREF.

5GNDGround. Signal and power return.

6VDD

Supply Voltage Input. Bypass to ground with a 10nF COG\NPO and 1µF X5R.

www.analog.com

FUNCTION

Analog Devices | 7MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

7REF2Reference Input 2

8REF1

Reference Input 19GAIN2Gain Selection Input 210GAIN1

Gain Selection Input 1

Detailed Description
Overview
The MAX49925 is a single-supply, high-accuracy, bidirectional current-sense amplifier with a high common-mode input
range extending from -40V to +76V. The input stage provides protection against voltage spikes and inductive kickbacks
from -42V up to +80V. The ±5μV (typ) input offset voltage and 0.3% (max) gain error help to ensure low system errors.
The input stage is specifically designed to suppress the disturbance of fast-PWM signals, which are common in motor
control applications. The MAX49925 is well-suited for in-phase current monitoring of inductive loads, such as motor
windings and solenoids that are driven by PWM signals. The MAX49925 is specified over the temperature range of -40°Cto +125°C and operates over the supply range of +2.7V and +5.5V.
The MAX49925 offers four gain options using GAIN1 and GAIN2.

PWM Rejection Input Stage
The proprietary input architecture is immune to the large PWM disturbances present in typical motor control applications.
The input stage is designed to withstand -40V to +76V common-mode input voltage without damage. The MAX49925’s
output recovers within 500ns from PWM edges with slew rates up to and beyond ±500V/µs.

Low Input Offset Voltage and Low Gain Error
The low input offset voltage of the MAX49925 allows accurate current measurement with low current-sense resistor
values. In addition, low current-sense resistors help minimize power dissipation and increases system efficiency. Thistechnique also enables extremely low input offset voltage drift over time and temperature to 50nV/°C. The optimized gainarchitecture achieves a gain error of less than 0.3% over the entire temperature range of -40°C to +125°C.

Output Stage
Use the following equation to set the gain:
VOUT = {{ISENSE × RSENSE} x GAIN} + VREF...(1)Where ISENSE is the current though the sense resistor, RSENSE is the sense resistor value, and GAIN is the voltage gainof the MAX49925. the output stage is needed to generate suitable output voltage levels and set the different gain byexternal gain setting pins. This is an external voltage reference connected to REF1 and REF2 input. When the sense
current is positive (the current flows from the RS+ input to the RS- input through the sense resistor), the output voltage isgreater than VREF = (VREF1 + VREF2)/2 (V), when the sense current is negative, the output voltage is less than VREF =(VREF1 + VREF2)/2 (V) indicating negative currents flowing with respect to RS+ and RS- inputs.

Applications Information
Important Considerations
Stray Inductance
The stray inductance due to package parasitics in the current-sense resistor must be kept to a minimum. The unwanted
voltage error produced by the stray inductance is proportional to the magnitude of the load current. Wire-wound resistors
have the highest inductance, while metal film is comparably 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 straight bands of metal
and are available in values under 100mΩ.
Kelvin Connections
Due to the high currents that may flow through RSENSE, take care to eliminate solder and parasitic trace resistance from
causing errors in the sense voltage. Either use a four-terminal current sense resistor or use Kelvin (force and sense) PCB
layout techniques. Figure 1 shows a typical routing of Kelvin-sensed traces to the inputs of the MAX49925. The Kelvinsense traces should be as close as possible to the current-sense resistor's solder contact pads. If the Kelvin-sensing
contact pads are spaced wider relative to the sense resistor, error is introduced from the additional trace resistance.
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Analog Devices | 8

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection
VDD
PCB TRACERSENSE

ILOAD

RSOUT
RS+

MAX49925

Figure 1. Kelvin Sensing

Typical Application Circuits
Current Sensing in a 3-Phase Servo Motor

VPOWER = 9V TO 48V
RSENSE_POWER

Q1

Q2

Q3
R

VDD

MAX49925
RSENSEQ1REF

OUT(Q1)VDD

R
OUT(Q3)

MAX49920

VDD

R
RSENSEQ2

REF

MAX49925

OUT(Q2)

200k
100k

Q1

Q2

RSENSE_PGND

www.analog.com

Q3
R = 5kOUT(Q3) (V) = VREF (V) - (OUT(Q1) - OUT(Q2)) (V)

Analog Devices | 9

MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifier
with Fast PWM Rejection

Ordering Information
PART NUMBER

TEMP RANGE

PIN-PACKAGETOP MARK

PACKAGE CODE

MAX49925ATB/VY+-40°C to +125°C

10 TDFN

BEI

T1033Y+1C

MAX49925ATB/VY+T-40°C to +125°C

10 TDFN

BEI

T1033Y+1C

MAX49925XATB+-40°C to +125°C

10 TDFN

BER

T1033+1C

MAX49925XATB+T-40°C to +125°C

10 TDFN

BER

T1033+1C+Denotes a lead (Pb)-free/RoHS-compliant package.
T = Tape and reel.
X denotes an industrial qualified part.
/V denotes an automotive qualified part.
Y = Side-wettable package.

www.analog.com

Analog Devices | 10MAX49925

Bidirectional, Wide Positive and Negative
Sensing Range, Current-Sense Amplifierwith Fast PWM Rejection

Revision History
REVISIONNUMBER
012REVISIONDESCRIPTION
DATE
1/23
Initial release
Updated Benefits and Features, Electrical Characteristics table, and4/23
Ordering Information table
7/23
Updated Title and Benefits and Features section

PAGES
CHANGED—1, 3, 4, 11
1-12

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 | 11