ST1S40

Functional description

Doc ID 17928 Rev 4

13/30

An additional mechanism is protecting the device in case of short-circuit on the output and

high input voltage. A further threshold (OCP2, 1A higher than OCP1) is compared to the

inductor current. If the inductor current exceeds OCP2, the device stops switching and

restarts with a soft-start cycle.

5.4

Enable function

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

than 0.4 V, the device is disabled and the power consumption is reduced to less than 15 µA.

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

5.5

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.