Datasheet

TPS54527

SLVSAY5C –JULY 2011–REVISED MAY 2012

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cycle begins. In subsequent switching cycles, the on-time is set to a fixed value and the current is monitored in

the same manner. If the over current condition exists for 7 consecutive switching cycles, the internal OCL

threshold is set to a lower level, reducing the available output current. When a switching cycle occurs where the

switch current is not above the lower OCL threshold, the counter is reset and the OCL limit is returned to the

higher value.

There are some important considerations for this type of over-current protection. The peak current is the average

load current plus one half of the peak-to-peak inductor current. The valley current is the average load current

minus one half of the peak-to-peak inductor current. Since the valley current is used to detect the overcurrent

threshold, the load current is 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. When the over current condition is removed, the output voltage will return to the regulated value. This

protection is non-latching.

UVLO Protection

Undervoltage lock out protection (UVLO) monitors the voltage of the V

REG5

pin. When the V

REG5

voltage is lower

than UVLO threshold voltage, the TPS54527 is shut off. This protection is non-latching.

Thermal Shutdown

TPS54527 monitors the temperature of itself. If the temperature exceeds the threshold value (typically 165°C),

the device is shut off. This is non-latch protection.

Product Folder Link(s): TPS54527