TPS54225-Q1

SLVSAV9

– JUNE 2011

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There are some important considerations for this type of over-current protection. The load current one half of the

peak-to-peak inductor current higher than the over-current threshold. Also when the current is being limited, the

output voltage tends to fall as the demanded load current may be higher than the current available from the

converter. This may cause the output under-voltage protection circuit to be activated. When the over current

condition is removed, the output voltage will return to the regulated value. This protection is non-latching.

Over/Undervoltage Protection

The TPS54225-Q1 detects over and undervoltage conditions by monitoring the feedback voltage (VFB). This

function is enabled after approximately 1.7 times the soft-start time.When the feedback voltage becomes higher

than 120% of the target voltage, the OVP comparator output goes high and the circuit latches the high-side

MOSFET driver turns off and the low-side MOSFET turns on. When the feedback voltage becomes lower than

70% of the target voltage, the UVP comparator output goes high and an internal UVP delay counter begins. After

250

μs, the device latches off both internal top and bottom MOSFET.

UVLO Protection

than UVLO threshold voltage, the TPS54225-Q1 is shut off. This is protection is non-latching.

Thermal Shutdown

Thermal protection is self-activating. If the junction temperature exceeds the threshold value (typically 150

°C),

the TPS54225-Q1 shuts off. This protection is non-latching.

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© 2011, Texas Instruments Incorporated