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INA282 Deep Dive: High-Precision Current Sensing with a 10kHz Catch

  • Contents

Quick-Reference Card: INA282 at a Glance

Attribute Detail
Component Type Bidirectional Current Sense Amplifier
Manufacturer Texas Instruments
Key Spec -14V to +80V Common-Mode Range
Supply Voltage 2.7V to 18V
Package Options SOIC-8, VSSOP-8
Lifecycle Status Active
Best For High-precision industrial and automotive current monitoring


1. What Is the INA282? (Definition + Architecture)

The INA282 is a high-accuracy, bidirectional, zero-drift voltage output current shunt monitor from Texas Instruments that senses voltage drops across shunts at common-mode voltages from -14V to +80V, independent of the supply voltage. Unlike standard operational amplifiers, it is specifically engineered to extract a small differential signal (the drop across a shunt resistor) while rejecting massive common-mode swings.

1.1 Core Architecture & Design Philosophy

The INA282 utilizes a zero-drift, chopped architecture. By internally "chopping" the signal, the device constantly nulls its own offset voltage. For the engineer, this means an incredibly low offset of ±20 μV. The design philosophy favors DC precision and thermal stability over raw speed. It is a "voltage out" device with a fixed gain of 50 V/V, simplifying the signal chain by removing the need for external gain-setting resistors that could introduce tempco errors.

1.2 Where It Fits in the Signal Chain / Power Path

The INA282 sits directly across a low-value shunt resistor (typically mΩ range) located in either the high-side or low-side of a power rail. Its output is an analog voltage proportional to the current, usually fed directly into the ADC of a microcontroller (MCU) or a standalone comparator for overcurrent detection.

INA282 functional block diagram showing internal gain stages and chopper-stabilized front end


2. Electrical Characteristics: The Numbers That Matter

2.1 Power Supply & Consumption Profile

The device operates on a flexible 2.7V to 18V supply. With a maximum quiescent current of 900 μA, it is relatively "thirsty" compared to nanopower monitors, but this power is the trade-off for its high Common-Mode Rejection Ratio (CMRR) of 140 dB.

2.2 Performance Specs (Speed, Accuracy, or Efficiency)

  • Accuracy: The ±20 μV offset and 0.3 μV/°C drift ensure that your "zero current" reading stays zero across the full industrial temperature range.
  • Bandwidth: The bandwidth is a modest 10 kHz.
    • So What? This is not the part for monitoring high-speed PWM motor phases or 100kHz switching transients; it is designed for steady-state or slow-moving current profiles.

2.3 Absolute Maximum Ratings — What Will Kill It

  • Common-Mode Voltage: 80V. Exceeding this on the IN+ or IN- pins will likely cause substrate breakdown.
  • Differential Input: While the common-mode is high, the differential voltage (IN+ to IN-) should stay within a range that doesn't saturate the 50 V/V gain stage relative to your supply voltage.

3. Pinout & Package Guide

INA282 pinout diagram for SOIC-8 and VSSOP-8

3.1 Pin-by-Pin Functional Groups

Pin Group Pins Function
Power V+, GND Supply (2.7V–18V) and Ground
Signal Input IN+, IN- Connect across the shunt resistor
Signal Output OUT Analog voltage output (Gain = 50)
Reference REF1, REF2 Sets the output quiescent level (for bidirectional sensing)

3.2 Package Variants & Soldering Notes

Package Pitch Thermal Pad? Soldering Method
SOIC (D) 1.27 mm No Easy Hand-Solder / Reflow
VSSOP (DGK) 0.65 mm No Reflow Recommended

3.3 Part Number Decoder

A typical part number like INA282AIDR breaks down as:

* INA282: Device family (50 V/V gain).

* A: Revision/Accuracy grade.

* I: Industrial temperature range (-40°C to 125°C).

* D: SOIC-8 package (DGK = VSSOP).

* R: Large reel (Tape & Reel).


4. Known Issues, Errata & Real-World Pain Points

4.1 Narrow Bandwidth (10kHz)

Problem: The 10kHz bandwidth is a significant bottleneck for fast transient detection.

Root Cause: The internal filtering and chopper architecture prioritize DC precision.

Fix: If you need to catch microsecond-scale overcurrent spikes, use a faster part like the INA193 or add a hardware comparator downstream.

4.2 Slow Feedback Loop in Control Systems

Problem: Using the INA282 in a tight PID loop for motor control can cause oscillations.

Root Cause: The phase shift introduced by the 10kHz pole adds latency to the feedback.

Fix: Model the 10kHz pole in your control loop software or slow down the loop frequency.

4.3 Common-Mode vs. Supply Voltage Confusion

Problem: Designers often assume the input voltage cannot exceed the supply voltage (V+).

Root Cause: Standard Op-Amp thinking.

Fix: The INA282 is designed specifically so that the -14V to +80V common-mode range is independent of the 3.3V or 5V supply. You can safely monitor a 48V rail while powering the IC from 3.3V.


5. Application Circuits & Integration Examples

Watch Tutorial: INA282

5.1 Typical Application: Industrial Battery Management (BMS)

In a BMS, the INA282 monitors charge and discharge cycles. By tying REF1 to GND and REF2 to V+, the output is biased to V+/2, allowing the MCU to read "negative" current (discharge) and "positive" current (charge).

5.2 Interface Example: Connecting to a Microcontroller

The OUT pin is low-impedance and can drive most MCU ADCs directly.

// Pseudocode for reading INA282 on an Arduino/STM32
float shuntResistor = 0.010; // 10 mOhms
float gain = 50.0;
int adcValue = analogRead(A0);
float vOut = (adcValue / 1024.0) * 5.0; // Assuming 5V ADC ref
float current = (vOut - vRef) / (gain * shuntResistor);

6. Alternatives, Replacements & Cross-Reference

6.1 Pin-Compatible Drop-In Replacements

Part Number Manufacturer Key Difference Compatible?
INA283 TI Gain = 200 V/V ? (Pin-compatible)
INA284 TI Gain = 500 V/V ? (Pin-compatible)
AD8211 Analog Devices High bandwidth (500kHz), lower CM range ?? (Verify Pinout)

6.2 Upgrade Path (Better Performance)

For applications requiring digital output directly (I2C/SMBus), the INA226 offers 16-bit resolution and integrated bus voltage monitoring, though it is not a pin-compatible analog replacement.


7. Procurement & Supply Chain Intelligence

  • Lifecycle Status: Active. This is a mature, widely used part with no immediate EOL (End of Life) risk.
  • Typical MOQ & Lead Time: Available in small quantities (cut tape) from major distributors. High-volume lead times are typically 8–12 weeks.
  • BOM Risk Factors: Low. As a Texas Instruments "standard" part, it is multi-fabbed.
  • Authorized Distributors: Digi-Key, Mouser, Arrow, and Avnet.

8. Frequently Asked Questions

Q: What is the INA282 used for? It is primarily used for high-side or low-side current sensing in industrial automation, motor control, and automotive battery management where high precision and wide common-mode rejection are required.

Q: What are the best alternatives to the INA282? If you need higher bandwidth, look at the Analog Devices AD8211 or LT6106. For higher gain in the same family, use the INA283 (Gain 200) or INA284 (Gain 500).

Q: Is the INA282 still in production? Yes, it is an active product and widely supported by Texas Instruments for new designs.

Q: Can the INA282 work with 3.3V logic? Yes. It can be powered by 3.3V, and its output will be compatible with 3.3V MCU ADCs, even while sensing currents on an 80V rail.


9. Resources & Tools

  • Official Datasheet: [Texas Instruments INA282 Product Page]
  • Evaluation Board: INA282EVM
  • Reference Designs: TIDA-00302 (Current Sensing for Solar)
  • SPICE Model: Available on TI.com for TINA-TI and PSpice.

INA282-286EVM Documents & Media

Download datasheets and manufacturer documentation for Texas Instruments INA282-286EVM.

INA282-286EVM PCB Symbol, Footprint & 3D Model

Texas Instruments INA282-286EVM

Texas Instruments

Power Management IC Development Tools INA282-286 Eval Mod

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