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:

CFILTER

RFILTER

< 10 :

RSENSE

25

INA302, INA303

www.ti.com

SBOS775C – SEPTEMBER 2016 – REVISED MARCH 2019

Product Folder Links: INA302 INA303

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8.1.2 Input Filtering

The integrated comparators in the INA30x are very accurate at detecting out-of-range events because of the low

offset voltage; however, noise present at the input of the current-sense amplifier and noise internal to the device

can make the offset appear larger than specified. The most obvious effect that external noise can have on the

operation of a comparator is to cause a false alert condition. If a comparator detects a large noise transient

coupled into the signal, the device can easily falsely interpret this transient as an overrange condition.

External filtering helps reduce the amount of noise that reaches the comparator and reduce the likelihood of a

false alert from occurring because of external noise. The trade-off to adding this noise filter is that the alert

response time is increased because the input signal and the noise are filtered. Figure 48 shows the

implementation of an input filter for the device.

Figure 48. Input Filter Implementation

Limiting the amount of input resistance used in this filter is important because this resistance can have a

significant effect on the input signal that reaches the device input pins by adversely affecting the gain error of the

device. A typical system implementation involves placing the current-sensing resistor very near the device so the

traces are very short and the trace impedance is very small. This layout helps reduce coupling of additional noise

into the measurement. Under these conditions, the characteristics of the input bias currents have minimal effect

on device performance.