LT8642-1

Demonstration circuit 3162A is a 18V, 10A synchronous step-down Silent Switcher^® with spread spectrum frequency modulation featuring the LT8642-1. The demo board is designed for 1.2V output from a 2.8V to 18V input. The LT8642-1 is a compact, low emission, high efficiency, and high speed synchronous monolithic stepdown switching regulator. Special Silent Switcher architecture minimizes EMI emissions. Selectable spread spectrum mode can further improve EMI performance. Fast minimum on-time of 20ns enables high V_IN to low V_OUT conversion at high frequency.

The LT8642-1 switching frequency can be programmed either via a resistor or external clock over a 200kHz to 3MHz range. The default frequency of demo circuit 3162A is 2MHz. The LT8642-1 SYNC/MODE pin on the demo board is grounded (JP1 at BURST position) by default for low ripple Burst Mode^® operation. Spread spectrum mode and forced continuous mode can be selected respectively by moving JP1 shunt. To synchronize to an external clock, move JP1 to FCM/SYNC and apply the external clock to the SYNC terminal.

The LT8642-1 data sheet gives a complete description of the part, operation, and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 3162A. The LT8642-1 is assembled in a 3mm × 4mm LQFN package with exposed pads for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout and Thermal Considerations.