Demonstration circuit 2521A is a 42V, 1.5A micropower synchronous step-down regulator featuring the LT8608/ LT8608B. There are two assembly versions. DC2521A-A is for the LT8608 and DC2521A-B is for the LT8608B.
The LT8608/LT8608B is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator. Top and bottom power switches, compensation components and other necessary circuits are inside of the 2mm × 2mm DFN package to minimize external components and simplify design. The difference LT8608 and LT8608B is the LT8608 works under low ripple Burst Mode® operation at light load condition, while the LT8608B has pulse-skipping mode for light load. Due to the Burst Mode operation, LT8608 consumes only 1.7μA of quiescent current when output is regulated at 5V. LT8608B has higher quiescent current because of its pulse-skipping mode operation.
The demo board is designed for 5V output from a 5.5V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies.
The demo board has an EMI filter installed. To use the EMI filter, the input should be tied to VEMI, not VIN. An inductor L2, which is a 0Ω jumper on the board by default now, can be added in the EMI filter to further reduce the conducted emission.
The LT8608 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 DC2521A.