Upon overflow, the ENERGY register will roll over and start from zero. This register value can also be reset at

any time by setting the RSTACC bit in the CONFIG register.

An overflow event in the CHARGE register is indicated by the CHARGEOF bit. If an overflow condition occurs,

the CHARGE register needs to be manually reset by setting the RSTACC bit in the CONFIG register.

For a design example using these equations refer to Detailed Design Procedure.

8.1.2 ADC Output Data Rate and Noise Performance

The INA780x noise performance and effective resolution depend on the ADC conversion time. The device

also supports digital averaging which can further help decrease digital noise. The flexibility of the device to

select ADC conversion time and data averaging offers increased signal-to-noise ratio and achieves the highest

dynamic range with lowest offset. The profile of the noise at lower signals levels is dominated by the system

noise that is comprised mainly of 1/f noise or white noise. The INA780x effective resolution of the ADC can be

increased by increasing the conversion time and increasing the number of averages.

Table 8-2 summarizes the output data rate conversion settings supported by the device. The fastest conversion

setting is 50 µs. Typical noise-free resolution is represented as Effective Number of Bits (ENOB) based on

device measured data. The ENOB is calculated based on noise peak-to-peak values, which assures that full

noise distribution is taken into consideration.

Table 8-2. INA780x Noise Performance

ADC CONVERSION TIME

PERIOD [µs]

OUTPUT SAMPLE AVERAGING

[SAMPLES]

OUTPUT SAMPLE PERIOD [ms]

NOISE-FREE ENOB

CURRENT MEASUREMENT

50

1

0.05

10.4

84

0.084

10.4

150

0.15

11.1

280

0.28

11.7

540

0.54

12.4

1052

1.052

12.9

2074

2.074

13.1

4120

4.12

13.7

50

4

0.2

11.3

84

0.336

11.5

150

0.6

12.2

280

1.12

12.9

540

2.16

13.4

1052

4.208

13.7

2074

8.296

14.7

4120

16.48

14.7

50

16

0.8

12.2

84

1.344

13.1

150

2.4

13.4

280

4.48

13.7

540

8.64

14.1

1052

16.832

14.7

2074

33.184

15.7

4120

65.92

15.7

INA780A, INA780B

SBOSAB6 – JULY 2023

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