INA30x

GND

OUT

ALERT2

IN+

IN-

LOAD

Power Supply

0 V to 36 V

+

Gain = 20,

50, 100

LATCH1

RLIMIT2

LIMIT2

ALERT1

VS

2.7 V to 5.5 V

RPULL-UP2

DELAY

CDELAY

RLIMIT1

LIMIT1

LATCH2

Reference Voltage

REF

RPULL-UP1

ILIMIT1

ILIMIT2

CBYPASS

0.1 PF

10 k:

10 k:

RSENSE

+ (-)

- (+)

+

-

14

INA302, INA303

SBOS775C – SEPTEMBER 2016 – REVISED MARCH 2019

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Copyright © 2016–2019, Texas Instruments Incorporated

7 Detailed Description

7.1 Overview

The INA30x feature a zero-drift, 36-V, common-mode, bidirectional, current-sensing amplifier, and two high-

speed comparators that can detect multiple out-of-range current conditions. These specially designed, current-

sensing amplifiers can be used in both low-side or high-side applications where common-mode voltages far

exceed the supply voltage of the device. Currents are measured by accurately sensing voltages developed

across current-sensing resistors (also known as current-shunt resistors). Current can be measured on input

voltage rails as high as 36 V, and the device can be powered from supply voltages as low as 2.7 V.

The zero-drift topology enables high-precision measurements with maximum input offset voltages as low as

30 μV (max) with a temperature contribution of only 0.25 μV/°C (max) over the full temperature range of –40°C to

+125°C. The low total offset voltage of the INA302 enables smaller current-sense resistor values to be used,

improving power-efficiency without sacrificing measurement accuracy resulting from the smaller input signal.

Both devices use a single external resistor to set each out-of-range threshold. The INA302 allows for two

overcurrent thresholds, and the INA303 allows for both an undercurrent and overcurrent threshold. The response

time of the ALERT1 threshold is fixed and is less than 1 μs. The response time of the ALERT2 threshold can be

set with an external capacitor. The combination of a precision current-sense amplifier with onboard comparators

creates a highly-accurate solution that is capable of fast detection of multiple out-of-range conditions. The ability

to detect when currents are out-of-range allows the system to take corrective actions to prevent potential

component or system-wide damage.

7.2 Functional Block Diagram