AUIPS7125R

Current sensing accuracy

Iout

Ifb

Ifb leakage

Ifb2

Ifb1

Iout2

Iout1

I offset

The current sensing is specified by measuring 3 points :

- Ifb1 for Iout1

- Ifb2 for Iout2

- Ifb leakage for Iout=0

The parameters in the datasheet are computed with the following formula :

Ratio = ( Iout2 – Iout1 )/( Ifb2 – Ifb1)

I offset = Ifb1 x Ratio – Iout1

This allows the designer to evaluate the Ifb for any Iout value using :

Ifb = ( Iout + I offset ) / Ratio if Ifb > Ifb leakage

For some applications, a calibration is required. In that case, the accuracy of the system will depends on the variation of

the I offset and the ratio over the temperature range. The ratio variation is given by Ratio_TC specified in page 4.

The Ioffset variation depends directly on the Rdson :

I offset@-40°C= I offset@25°C / 0.8

I offset@150°C= I offset@25°C / 1.9

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