Demo circuit 1069A is a monolithic step-down switching regulator with LDO featuring LT3500. The demo circuit is designed for 5.0V and 3.3V outputs from a 6V to 36V input. The LDO output is configured as a post-regulator of the switching regulator output. The total current capability is up to 2A. The switching regulator can be synchronized to an external clock input or be resistor-programmed to a 250kHz to 2.2MHz internal oscillator. Programmable frequency allows for optimization between efficiency and external component size.
Cycle-by-cycle current limit, frequency foldback and thermal shutdown provide protections against a shorted output. The soft-start feature controls the ramp rate of the output voltage, eliminates input current surge during startup, and also provides output tracking.