DocID022998 Rev 4

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ST1S31

Functional description

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4.5

Enable function

The enable feature allows the device to be put into standby mode. With the EN pin is lower

than 0.4 V, the device is disabled and the power consumption is reduced to less than 10

A.

With the EN pin higher than 1.2 V, the device is enabled. If the EN pin is left floating, an

internal pull-down ensures that the voltage at the pin reaches the inhibit threshold and the

4.6

Light load operation

With peak current mode control loop the output of the error amplifier is proportional to the

load current. In the ST1S31 device, to increase light load efficiency when the output of the

error amplifier falls below a certain threshold, the high-side turn-on is prevented.

This mechanism reduces the switching frequency at light load in order to save the switching

losses.

4.7

Hysteretic thermal shutdown

The thermal shutdown block generates a signal that turns off the power stage if the junction

temperature goes above 150 °C. Once the junction temperature goes back to about 130 °C,

the device restarts in normal operation.