Current Sense Amplifiers and Shunt Monitors for Power Measurement
Product Specifications
Product Overview
Current measurement is the part of a design that quietly decides whether an overcurrent event protects the board or destroys it. A shunt resistor is simple, but the amplifier in front of it has to survive a common-mode voltage far above its own supply, reject the switching transients of the stage it is measuring, and hold its offset over temperature. Three symptoms come back again and again: a gain error that puts the real current outside the trip window, a common-mode range that is too narrow for the rail being measured, and a PWM edge that pushes the output far enough to trip the comparator behind it.
The families on this page cover the four ways that problem is normally solved. Analog voltage output parts give a direct gain of 20, 50, 100, 200 or 500 V/V into an ADC, including PWM rejecting versions built for motor phases. Current output parts allow the gain to be set by a single load resistor and are used where the measuring point is far from the controller. Digital monitors place the ADC, the multiplier and the calibration registers in the package and report current, bus voltage and power over I2C, which removes a separate converter from the board. Isolated Hall effect sensors sense the field around the conductor instead of a shunt drop, so the measurement survives a 2.4 kVRMS barrier and a 1.2 mOhm conductor.
All models are grouped into this single product, so one enquiry can cover the shunt, the amplifier, the digital monitor and the isolated option for the same current path. Tell us the maximum current, the shunt value, the common-mode voltage, the supply available and the accuracy you have to hold, and the class can be matched to the measurement instead of the other way round.
Key Specifications
| Parameter | Analog Current Sense Amplifiers | Digital I2C Monitors | Isolated Hall Sensors |
|---|---|---|---|
| Sensing method | Differential voltage across a shunt resistor | Shunt resistor plus internal ADC | Magnetic field from the conductor, no shunt |
| Common-mode range | -4 V to 110 V (INA293), -4 V to 80 V (INA240), 4.5 V to 76 V (MAX4080) | 0 V to 26 V (INA219), 0 V to 36 V (INA226) | Isolated, 2.4 kVRMS minimum |
| Gain and resolution | Fixed 20, 50, 100, 200 and 500 V/V, or set by the load resistor | 12-bit (INA219) and 16-bit (INA226) conversion | 66, 100 and 185 mV/A output sensitivity |
| Interface | Analog voltage output, or current output into a load resistor | I2C or SMBus, up to 16 addresses | Analog voltage output, ratiometric to the 5 V supply |
| Supply | 2.7 V to 5.5 V typical, single supply | 2.7 V to 5.5 V, independent of the bus | 5.0 V single supply |
| Accuracy | Offset 25 uV (INA240) to 150 uV (INA181), gain error 0.15% to 1% | 10 uV offset and 0.1% gain error maximum (INA226) | 1.5% total output error at 25 C |
| Speed | 1.3 MHz bandwidth and 2.5 V/us slew rate (INA293) | 140 us to 8.244 ms conversion time | 80 kHz bandwidth, 5 us output rise time |
| Temperature range | -40 C to 125 C on the catalog grades | -40 C to 125 C | -40 C to 85 C |
Included Models and Order Codes
The table lists the current sense classes most often requested for motor, battery, telecom and instrument boards. Send the complete order code including the gain letter, the package code and the temperature suffix and we confirm availability against that exact string.
| Model | Type | Common-Mode Range | Gain or Interface | Package | Notes |
|---|---|---|---|---|---|
| INA219AIDR | Digital current and power monitor | 0 V to 26 V | 12-bit I2C, PGA 1 to 8 | SOIC-8 | Reports current, voltage and power, 16 addresses |
| INA219BIDCNR | Digital current and power monitor | 0 V to 26 V | 12-bit I2C | SOT-23-8 | 0.5% accuracy version over temperature |
| INA226AIDGSR | Digital current and power monitor | 0 V to 36 V | 16-bit I2C | VSSOP-10 | 2.5 uV shunt LSB, 10 uV offset, alert pin |
| INA181A1IDBVR | Analog, bidirectional | -0.2 V to 26 V | 20 V/V | SOT-23-6 | 350 kHz, 1% gain error, 260 uA supply |
| INA181A2IDBVR | Analog, bidirectional | -0.2 V to 26 V | 50 V/V | SOT-23-6 | 210 kHz bandwidth |
| INA181A3IDBVR | Analog, bidirectional | -0.2 V to 26 V | 100 V/V | SOT-23-6 | 150 kHz bandwidth |
| INA181A4IDBVR | Analog, bidirectional | -0.2 V to 26 V | 200 V/V | SOT-23-6 | 105 kHz bandwidth |
| INA199A1DCKR | Analog, low or high side | -0.3 V to 26 V | 50 V/V | SC70-6 | 100 uA maximum supply current, 10 mV full scale |
| INA199A2DCKR | Analog, low or high side | -0.3 V to 26 V | 100 V/V | SC70-6 | 120 dB common-mode rejection |
| INA199A3DCKR | Analog, low or high side | -0.3 V to 26 V | 200 V/V | SC70-6 | For small shunt drops on battery boards |
| INA240A1PW | Analog with enhanced PWM rejection | -4 V to 80 V | 20 V/V | TSSOP-8 | 132 dB DC common-mode rejection |
| INA240A2PWR | Analog with enhanced PWM rejection | -4 V to 80 V | 50 V/V | SOIC-8 | 93 dB rejection at 50 kHz for motor phases |
| INA293A1IDBVR | Analog, high voltage | -4 V to 110 V | 20 V/V | SOT-23-5 | 1.3 MHz bandwidth, 0.15% gain error |
| INA293A3IDBVR | Analog, high voltage | -4 V to 110 V | 100 V/V | SOT-23-5 | For 48 V and 96 V battery rails |
| INA139NA/3K | Current output shunt monitor | 2.7 V to 40 V | Set by the load resistor | SOT-23-5 | 60 uA quiescent current, 1000 uA/V transconductance |
| INA169NA/3K | Current output shunt monitor | 2.7 V to 60 V | Set by the load resistor | SOT-23-5 | Gain from 1 to over 100 with one resistor |
| MAX4080FAUA+ | High-side, unidirectional | 4.5 V to 76 V | 5 V/V | 8-pin uMAX | 75 uA supply current, 0.1% full-scale accuracy |
| MAX4080TAUA+ | High-side, unidirectional | 4.5 V to 76 V | 20 V/V | 8-pin uMAX | Telecom and backplane current monitoring |
| MAX4080SAUA+ | High-side, unidirectional | 4.5 V to 76 V | 60 V/V | 8-pin uMAX | For small sense voltages at high supply |
| MAX4081FAUA+ | High-side, bidirectional | 4.5 V to 76 V | 5 V/V | 8-pin uMAX | External reference sets the zero current output |
| ACS712ELCTR-05B-T | Hall effect, isolated | 2.4 kVRMS isolation | 185 mV/A, plus/minus 5 A | SOIC-8 | 1.2 mOhm conductor, 80 kHz bandwidth |
| ACS712ELCTR-20A-T | Hall effect, isolated | 2.4 kVRMS isolation | 100 mV/A, plus/minus 20 A | SOIC-8 | Output centred at half the supply |
| ACS712ELCTR-30A-T | Hall effect, isolated | 2.4 kVRMS isolation | 66 mV/A, plus/minus 30 A | SOIC-8 | For charger and inverter current paths |
Key Features
Common-Mode Range Matched To The Rail – 26 V parts for logic and 24 V rails, 76 V and 80 V parts for telecom and motor buses, and 110 V parts for high voltage battery packs, all independent of the amplifier supply.
Fixed Gains Across One Family – 20, 50, 100, 200 and 500 V/V options in the same family and the same footprint, so the shunt can be chosen for power loss rather than for the gain available.
Digital Output Without A Second ADC – The I2C monitors resolve the shunt voltage and the bus voltage inside the package and report current and power in engineering units, with 12-bit and 16-bit versions and programmable averaging.
PWM Rejection For Motor Phases – The PWM rejecting parts keep a 132 dB DC and 93 dB AC common-mode rejection at 50 kHz, so an inverter phase current can be read without the transient recovery ripple that usually forces extra filtering.
Current Output For Remote Sensing – Current output monitors drive a load resistor at the controller end, which sets the gain between 1 and over 100 and keeps a small signal immune over a long cable.
Isolated Sensing Without A Shunt – Hall effect sensors sense the field around the conductor and hold a 2.4 kVRMS barrier with a 1.2 mOhm internal conductor, which suits mains referenced and high current paths where a shunt would dissipate too much.
Accuracy Stated Per Grade – Offset from 10 uV to 150 uV and gain error from 0.1% to 1% depending on the part and the grade, and the grade is written on the quote rather than left to the suffix.
Applications
Boards where these parts are specified: A current sense front end is normally quoted together with the SUPERB PCB and SUPERB PCBA work we support for the same board, so the shunt, the amplifier and the assembly arrive as one line.
Motor And Servo Drives – Phase current feedback, overcurrent trip levels and torque control on brushless and PMSM drives where the PWM edge has to be rejected.
Battery And BMS Boards – Pack current, charge and discharge direction and coulomb counting on 24 V, 48 V and higher battery rails, including the isolated option for mains referenced stacks.
Telecom And Industrial Power – Load sharing, hot swap current limits and output current reporting on rectifiers and DC power systems where the bus runs well above the logic supply.
Test And Measurement – Bench supplies, electronic loads and instrument front ends that need a calibrated current reading with the offset and the gain error known.
Sourcing and Cross-Reference
Current sense amplifiers are a common casualty of end of life, and the substitutes are rarely drop in. Gain, direction, reference pin, package and common-mode range all differ between families, and a part that looks equivalent on the front page of a data sheet can be unidirectional where the original was bidirectional or have no reference pin at all. We state which of those differ before the parts are ordered.
For an obsolete device we check the current family from the same vendor first, then the wider market. Where the package and the pin out are published as compatible, the cross reference is supplied with the quote. Where the substitute needs a different reference connection, a different shunt value or an added filter, that is written down rather than discovered on the line.
Shunt based and Hall based measurement are not interchangeable, so when a shunt part has gone obsolete the quote states the isolated alternative and the accuracy that comes with it. The intent pages on obsolete part replacement and BOM shortage recovery set out how that search is run, and the same process applies to a single line or to a whole current measurement section.
Where the board is built in volume, SUPERB Assembly support covers the SMT build of the sensing section.
Q: Can you supply pin to pin replacements for discontinued current sense amplifier part numbers?
A: Yes. Send the complete order code and the quantity and the SUPERB Tech sales team will confirm availability and the nearest pin compatible option with the gain and the common-mode range stated.
Why Source Current Sense Amplifiers from Superb Automation?
- Sourcing Focus: Analog, power, RF and mixed signal parts for industrial, telecom, medical and defence builds, quoted by people who read the specification tables.
- Hard To Find And Obsolete Parts: Amplifier families that reach end of life while the platform stays in service, sourced with the last time buy position or the nearest equivalent stated up front.
- Cross Reference Support: Gain, direction, common-mode range, reference pin and package differences listed with the quote so a substitute can be signed off before production.
- Stock And Build Quantities: Prototype samples, repair quantities and volume orders are all welcome, with the batch information given per line.
- Shunt And Sensor Kitting: The amplifier, the shunt resistor, the filter parts and the isolated alternative for the same current path can be quoted together.
- Reply With Evidence: Documents, batch marking and part condition are stated on the quote before the order is placed.
Related Product Families
This page is part of the component range we supply for industrial, telecom, medical and defence builds. Continue with: Amplifiers and Comparators, Precision Operational Amplifiers for Sensor Signal Chains, Power Management ICs for Optical Module and Instrument Boards, Obsolete RF Part Replacement.