ZHCSQP8J December 2008 – June 2022 LM5088 , LM5088-Q1
PRODUCTION DATA
The LM5088 contains a current limit feature that protects the circuit from extended overcurrent conditions. The emulated current signal is directly proportional to the buck switch current and is applied to the current limit comparator. If the emulated current exceeds 1.2 V, the PWM cycle is terminated. The peak inductor current required to trigger the current limit comparator is given by:
where
Since the current that charges the RAMP capacitor is proportional to VIN – VOUT, if the output is suddenly shorted, the VOUT term is zero and the RAMP charging current increases. The increased RAMP charging current immediately reduces the PWM duty cycle. The LM5088 also includes a buck switch protection scheme. A dedicated comparator monitors the drain-to-source voltage of the buck FET when it is turned on, if the VDS exceeds 1.5 V, the comparator turns off the buck FET immediately. This feature helps protect the buck FET in catastrophic conditions, such as a sudden saturation of the inductor.