Table 8-2. INA232 Noise Performance (continued)

ADC CONVERSION

TIME PERIOD [µs]

OUTPUT SAMPLE

AVERAGING

[SAMPLES]

OUTPUT SAMPLE PERIOD

[ms]

NOISE-FREE ENOB

(±81.92-mV) (ADCRANGE

= 0)

NOISE-FREE ENOB

(±20.48-mV) (ADCRANGE

= 1)

1100

256

281.6

16.0

16.0

2116

256

541.696

16.0

16.0

4156

256

1063.936

16.0

16.0

8244

256

2110.464

16.0

16.0

140

512

71.68

16.0

15.1

204

512

104.448

16.0

15.7

332

512

169.984

16.0

16.0

588

512

301.056

16.0

16.0

1100

512

563.2

16.0

16.0

2116

512

1083.392

16.0

16.0

4156

512

2127.872

16.0

16.0

8244

512

4220.928

16.0

16.0

140

1024

143.36

16.0

15.7

204

1024

208.896

16.0

16.0

332

1024

339.968

16.0

16.0

588

1024

602.112

16.0

16.0

1100

1024

1126.4

16.0

16.0

2116

1024

2166.784

16.0

16.0

4156

1024

4255.744

16.0

16.0

8244

1024

8441.856

16.0

16.0

8.1.4 Filtering and Input Considerations

Measuring current is often noisy and such noise can be difficult to define. The INA232 offers several options

for filtering by allowing the conversion times and number of averages to be selected independently in the

Configuration register (0h). The conversion times can be set independently for the shunt voltage and bus voltage

measurements to allow added flexibility when configuring the monitoring of the power-supply bus.

The internal ADC is based on a delta-sigma (ΔΣ) front-end with a 500-kHz (±10% maximum) sampling rate.

This architecture has good inherent noise rejection; however, transients that occur at or very close to the

sampling rate harmonics can cause problems. These signals are at 1 MHz and higher and can be managed

by incorporating filtering at the device input. The high frequency enables the use of low-value series resistors

on the filter with negligible effects on measurement accuracy. In general, filtering the device input is only

necessary if there are transients at exact harmonics of the 500 kHz (±10% maximum) sampling rate (greater

than 1 MHz). Filter using the lowest possible series resistance (typically 100 Ω or less) and a ceramic capacitor.

Recommended values for this capacitor are between 0.1 µF and 1 µF. Figure 8-1 shows the device with a filter

added at the input.

INA232

SBOSAA2 – DECEMBER 2022

www.ti.com

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