TPS54331

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SLVS839F – JULY 2008 – REVISED OCTOBER 2014

8.3.10 Overvoltage Transient Protection

The TPS54331 device 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

8.3.11 Thermal Shutdown

The device implements an internal thermal shutdown to protect the device 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. When the die temperature decreases below 165°C, the device reinitiates the power-up

sequence.

8.4 Device Functional Modes

8.4.1 Eco-mode™

The TPS54331 device is designed to operate in pulse skipping Eco-mode at light load currents to boost light load

efficiency. When the peak inductor current is lower than 160 mA (typical), the COMP pin voltage falls to 0.5 V

(typical) and the device enters Eco-mode. When the device is in Eco-mode, the COMP pin voltage is clamped at

0.5-V internally which prevents the high-side integrated MOSFET from switching. The peak inductor current must

rise above 160 mA for the COMP pin voltage to rise above 0.5 V and exit Eco-mode. Because the integrated

current comparator catches the peak inductor current only, the average load current entering Eco-mode varies

with the applications and external output filters.

The device is recommended to operate with input voltages above 3.5 V. The typical VIN UVLO threshold is not

specified and the device can operate at input voltages down to the UVLO voltage. At input voltages below the

actual UVLO voltage, the device does not switch. If the EN pin is externally pulled up or left floating, the device

becomes active when the VIN pin passes the UVLO threshold. Switching begins when the slow-start sequence is

initiated.

8.4.3 Operation With EN Control

The enable threshold voltage is 1.25 V (typical). With the EN pin is held below that voltage the device is disabled

and switching is inhibited even if the VIN pin is above the UVLO threshold. The IC quiescent current is reduced

in this state. If the EN voltage increases above the threshold while the VIN pin is above the UVLO threshold, the

device becomes active. Switching is enabled, and the slow-start sequence is initiated.

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