The LM61435-Q1 is in active mode whenever the EN pin is above VEN, VIN is high enough to satisfy VIN_OPERATE, and no other fault conditions are present. The simplest way to enable the operation is to connect the EN pin to VIN, which allows self start-up when the applied input voltage exceeds the minimum VIN_OPERATE.
In active mode, depending on the load current, input voltage, and output voltage, the LM61435-Q1 is in one of five modes:
- Continuous conduction mode (CCM) with fixed switching frequency when load current is above half of the inductor current ripple.
- Auto Mode - Light Load Operation: PFM when switching frequency is decreased at very light load.
- FPWM Mode - Light Load Operation: Discontinuous conduction mode (DCM) when the load current is lower than half of the inductor current ripple.
- Minimum on-time: At high input voltage and low output voltages, the switching frequency is reduced to maintain regulation.
- Dropout mode: When switching frequency is reduced to minimize voltage dropout.