Demonstration circuit 2523A is an 18V, 8.5A (continuous)/12A (peak) synchronous step-down Silent Switcher® with 16µA quiescent current featuring the LT8652S. The LT8652S is a compact, high efficiency, high speed synchronous monolithic step-down switching with the second generation Silent Switcher structure that minimizes EMI and reduces PCB layout sensitivity. Top and bottom power switches, compensation components and other necessary circuits are inside of the LT8652S to minimize external components and simplify design. The demo board has two outputs: 3.3V and 1.2V from a 3.6V to 18V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies.
The SYNC pin on the demo board is grounded by default for low ripple Burst Mode® operation. Move JP2 to FCM without SSM position can change the operation mode to forced continuous mode operation. Once JP2 is on FCM with SSM position, VCC is applied to the SYNC pin for low EMI spread spectrum operation. To synchronous to an external clock, move JP2 to SYNC and apply the external clock to the SYNC turret.
The demonstration circuit 2523A runs at 2MHz to minimize solution size. The peak efficiency is 90%. The IC temperature rise is less than 70°C when both channels run at full load, 8.5A each, at 2MHz.
The demo board has EMI filters installed for both channels. To use the EMI filter, the input should be tied to VEMI1/VEMI2, not VIN1/VIN2.
The LT8652S 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 DC2523A.