Detailed description

ST1S15

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DocID023280 Rev 4

7.6

Thermal protection

The device also has thermal shutdown protection, which is active when the junction

temperature reaches 125 °C. In this case both the high and low-side MOSFETs turn off.

Once the junction temperature goes back below 95 °C, the device resumes normal

operation.

7.7

Overcurrent protection

The overcurrent protection limits the maximum inductor current. This current, flowing

switching node. A comparator compares the switching node voltage with a reference

voltage VR. To generate the VR voltage a current generator is used, which causes a drop

across a P-channel of the same kind as the power stage. When the switching node voltage

is lower than VR, the comparator output goes high and the power P-channel turns off.

7.8

Enable function

The ST1S15 features an enable function (B2). When the EN voltage is higher than 1.2 V

the device is ON, and if it is lower than 0.4 V the device is OFF. In shutdown mode the

consumption is lower than 5 µA. The EN pin does not have an internal pull-up, which

means that the EN pin cannot be left floating. If the enable function is not used, the EN pin