Texas Instruments INA821IDGKR

Overview

INA821IDGKR from Texas Instruments is a precision instrumentation amplifier with 35-µV maximum input offset voltage, 7-nV/√Hz input voltage noise, and 4.7-MHz bandwidth at G = 1. It features ±40-V input overvoltage protection, 112-dB minimum CMRR at G = 10, and operates from ±2.25 V to ±18 V dual supplies or 4.5 V to 36 V single supply. It is used in ECG front-ends and industrial process analytics for high-accuracy differential signal conditioning.

For engineers reviewing the INA821IDGKR datasheet, INA821IDGKR pinout, INA821IDGKR application, or INA821IDGKR equivalent, key selection criteria include input offset drift (0.4 µV/°C), gain-setting resistor configuration (RG pins 2 & 3), reference input impedance (10 kΩ), stable operation with 1-nF capacitive loads, and thermal performance in the 3.00 mm × 3.00 mm VSSOP package.

Technical Context

The INA821IDGKR employs super-beta input transistors to achieve low input bias current (0.15–0.5 nA) and ultra-low input voltage noise (7 nV/√Hz). Its three-op-amp architecture enables high common-mode rejection (112 dB min at G = 10) and precise gain control via external resistor RG between pins 2 and 3.

It integrates overvoltage protection on both inputs up to ±40 V relative to supplies and supports rail-to-rail output swing within 150 mV of rails. The device is specified across –40°C to +125°C and maintains 0.025% max gain error at G = 10 with ±35 ppm/°C gain drift.

Key Specifications

Pinout & Package

The INA821IDGKR is housed in an 8-pin VSSOP (DGK) package measuring 3.00 mm × 3.00 mm with exposed thermal pad internally connected to –VS.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar instrumentation amplifier applications.

Compared with INA819IDGKR and INA828IDGKR, the INA821IDGKR delivers the best combination of low noise (7 nV/√Hz), high bandwidth (4.7 MHz), and tightest offset specification (35 µV max) in the VSSOP-8 package-making it optimal for high-fidelity signal chains where resolution and speed are jointly constrained.

Availability

INA821IDGKR is available at Aetrix Electronics and suitable for analog input modules, electrocardiogram (ECG) systems, and flow transmitter designs requiring stable component supply, long-term manufacturability, and guaranteed traceability.

Supply support for INA821IDGKR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor company delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The INA821 belongs to TI's precision instrumentation amplifier product line, engineered for high-accuracy, low-noise signal conditioning in demanding sensor interface applications across medical, test & measurement, and process control domains.

FAQ

What is the maximum input offset voltage specification for the INA821IDGKR?

The INA821IDGKR has a maximum input offset voltage of 35 µV at 25°C, with a worst-case drift of 0.4 µV/°C over the full –40°C to +125°C operating range. This value is confirmed in the Electrical Characteristics table of the SBOS893D datasheet for the IDGKR (VSSOP) variant. The low offset enables accurate amplification of µV-level sensor signals without significant DC error contribution from the INA821IDGKR itself.

How is gain configured on the INA821IDGKR?

Gain on the INA821IDGKR is set by an external resistor RG connected between pins 2 and 3, using the equation G = 1 + 49.4 kΩ / RG. For example, a 494-Ω resistor yields G = 101. The INA821IDGKR supports gains from 1 to 10,000 and remains stable with capacitive loads up to 1 nF. This resistor-based configuration avoids digital overhead while ensuring predictable, temperature-stable gain scaling across the operating range.

Does the INA821IDGKR require external input protection circuitry?

No, the INA821IDGKR includes integrated overvoltage protection on both input terminals rated to ±40 V relative to the supply rails. This eliminates the need for external clamping diodes or series resistors in most industrial field-wiring scenarios. The protection operates without degrading CMRR or introducing leakage current, preserving signal integrity even during fault conditions-confirmed in the Absolute Maximum Ratings and Features sections of the INA821IDGKR datasheet.

What is the thermal pad connection requirement for the INA821IDGKR VSSOP package?

The thermal pad on the INA821IDGKR (DGK package) is internally connected to the –VS pin. It must be externally soldered to a PCB copper pour tied to the negative supply plane or left floating-TI does not recommend connecting it to ground or other potentials. Proper thermal pad layout reduces junction-to-board thermal resistance to 97.8°C/W, directly improving long-term reliability and sustained output current capability under continuous load.

Can the INA821IDGKR operate from a single 5-V supply?

Yes, the INA821IDGKR supports single-supply operation from 4.5 V to 36 V, including 5-V systems. When powered from +5 V and 0 V, its input common-mode range extends from +2 V to +3 V (per Figure 51), and output swings within 150 mV of each rail. To maximize dynamic range, the REF pin should be biased at mid-supply (e.g., 2.5 V) using a low-impedance source, as specified in the Recommended Operating Conditions section of the INA821IDGKR datasheet.