Demonstration circuit 1526 is a monolithic step-down DC/DC switching regulator featuring the LT3991. The switching frequency is adjustable up to 2MHz. The demo circuit is designed for 3.3V, 1.2A output from a 4.5V to 55V input. The wide input range of the LT3991 allows a variety of input sources including automotive batteries and 24V industrial supplies. Low ripple Burst Mode increases the efficiency at the light load while keeping the output ripple below 15mV. The part is in shutdown when the EN pin is low and active when the pin is high. The threshold of the EN pin is accurate at 1.01V with 30mV of hysteresis. When VIN is above 6V, adding a resistor divider from VIN to EN can program the LT3991 to regulate the output only when VIN is above a desired voltage. The circuit consumes only 2.8μA of quiescent current. The boost diode, control and logic circuit are integrated to reduce the components count and solution size. The current mode control scheme creates fast transient response and good loop stability.