TPS54331-Q1

SLVSAB5 – NOVEMBER 2010

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The TPS54331 provides robust protection during short circuits. There is potential for overcurrent runaway in the

output inductor during a short circuit at the output. The TPS54331 solves this issue by increasing the off time

during short circuit conditions by lowering the switching frequency. The switching frequency is divided by 8, 4, 2,

and 1 as the voltage ramps from 0 V to 0.8 V on VSENSE pin. The relationship between the switching frequency

and the VSENSE pin voltage is shown in Table 2.

Table 2. Switching Frequency Conditions

SWITCHING FREQUENCY

VSENSE PIN VOLTAGE

570 kHz

VSENSE

≥ 0.6 V

570 kHz / 2

0.6 V > VSENSE

≥ 0.4 V

570 kHz / 4

0.4 V > VSENSE

≥ 0.2 V

570 kHz / 8

0.2 V > VSENSE

OVERVOLTAGE TRANSIENT PROTECTION

The TPS54331 incorporates an overvoltage transient protection (OVTP) circuit to minimize output voltage

overshoot when recovering from output fault conditions or strong unload transients. The OVTP circuit includes an

overvoltage comparator to compare the VSENSE pin voltage and internal thresholds. When the VSENSE pin

voltage goes above 109% × Vref, the high-side MOSFET will be forced off. When the VSENSE pin voltage falls

below 107% × Vref, the high-side MOSFET will be enabled again.

THERMAL SHUTDOWN

The device implements an internal thermal shutdown to protect itself if the junction temperature exceeds 165°C.

The thermal shutdown forces the device to stop switching when the junction temperature exceeds the thermal

trip threshold. Once the die temperature decreases below 165°C, the device reinitiates the power up sequence.

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