Datasheet

TPS65930/TPS65920

SWCS037G–MAY 2008– REVISED APRIL 2011

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4.1.10 USB LDO Short-Circuit Protection Scheme

The short-circuit current for the LDOs and dc-dcs in the TPS65920 and TPS65930 devices is

approximately twice the maximum load current. When the output of the block is shorted to ground, the

power dissipation can exceed the 1.2-W requirement if no action is taken. A short-circuit protection

scheme is included in the TPS65920 and TPS65930 devices to ensure that if the output of an LDO or

dc-dc is short-circuited, the power dissipation does not exceed the 1.2-W level.

The three USB LDOs, VRUSB3V1, VRUSB1V8, and VRUSB1V5, are included in this short-circuit

protection scheme, which monitors the LDO output voltage at a frequency of 1 Hz and generates an

interrupt (sc_it) when a short-circuit is detected.

The scheme compares the LDO output voltage to a reference voltage and detects a short-circuit if the

LDO voltage drops below this reference value (0.5 or 0.75 V programmable). In the case of the

VRUSB3V1 and VRUSB1V8 LDOs, the reference is compared with a divided down voltage (1.5 V typical).

If a short-circuit is detected on VRUSB3V1, the power subchip FSM switches this LDO to sleep mode.

If a short-circuit is detected on VRUSB1V8 or VRUSB1V5, the power subchip FSM switches off the

relevant LDO.

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