7 Detailed Description

7.1 Overview

The INA333-Q1 is a monolithic instrumentation amplifier (INA) based on the precision zero-drift INA333-Q1

(operational amplifier) core. The INA333-Q1 also integrates laser-trimmed resistors to maintain excellent

common-mode rejection and low gain error. The combination of the zero-drift amplifier core and the precision

resistors allows this device to achieve outstanding dc precision, and makes the INA333-Q1 an excellent choice

for many 3.3-V and 5-V automotive applications.

7.2 Functional Block Diagram

RFI Filtered Inputs

RFI Filtered Inputs

50 k

RFI Filtered Inputs

RFI Filtered Inputs

50 k

150 k

150 k

150 k

150 k

INA333-Q1

1

8

6

5

2

3

VOUT

REF

VIN-

VIN+

RG

A1

A2

–

–

+

+

7

V+

4

V

A3

–

+

G = 1 +

100 k

RG

7.3 Feature Description

7.3.1 Internal Offset Correction

The INA333-Q1 internal operational amplifiers use an autocalibration technique with a time-continuous, 350

‑kHz

operational amplifier in the signal path. The amplifier is zero-corrected every 8 µs using a proprietary technique.

At power up, the amplifier requires approximately 100 µs to achieve the specified VOS accuracy. This design has

no aliasing or flicker noise.

7.3.2 Input Protection

The input pins of the INA333-Q1 are protected with internal diodes connected to the power-supply rails. These

diodes clamp and prevent the applied signal from damaging the input circuitry. If the input signal voltage exceeds

the power supplies by greater than 0.3 V, limit the input signal current to less than 10 mA to protect the internal

clamp diodes. This current limiting is generally done with a series input resistor. Some signal sources are

inherently current-limited and do not require limiting resistors.

7.4 Device Functional Modes

The INA333-Q1 has a single functional mode, and is operational when the power-supply voltage is greater than

1.8 V. The recommended maximum specified power-supply voltage for the INA333-Q1 is 5.5 V.

www.ti.com

INA333-Q1

SBOS464B – SEPTEMBER 2019 – REVISED JUNE 2023

Copyright © 2023 Texas Instruments Incorporated

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Product Folder Links: INA333-Q1