DC2564A: 5V @ 350mA, 5.5 ~ 42V in, Buck

Demonstration Circuit 2564A is a 42V, 0.35A micropower synchronous step-down regulator featuring the LT®8606. 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 LT8606 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes less than 3µA of quiescent current when output is regulated at 5V. Top and bottom power switches, compensation components and other necessary circuits are inside of the LT8606 to minimize external components and simplify design.

The SYNC pin on the demo board is grounded by default for low ripple Burst Mode® operation. Move JP1 to PULSE SKIPPING position can change the operation mode to pulse-skipping operation. Once JP1 is on SPREAD SPECTRUM position, VCC is applied to the SYNC pin for low EMI spread spectrum operation. To synchronous to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Figure 1 shows the efficiency of the circuit.

The demo board has an EMI filter installed. The radiated EMI performances of the board (with EMI filter) are shown in Figures 2 and 3. The red/green lines in Figures 2 and 3 are CISPR25 Class 5 peak/average limit. 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 LT8606 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 DC2564A.