Micrel, Inc.

MIC28500

June 2011

3

M9999-060311-B

Pin Description (Continued)

Pin

Number

Pin Name

Pin Function

20

BST

Boost (Output): Bootstrapped voltage to the high-side N-channel internal MOSFET driver. A Schottky

diode is connected between the VDD pin and the BST pin. A boost capacitor of 0.1μF is connected

between the BST pin and the SW pin.

4, 9, 10,

11, 12

SW

Switch Node (Output): Internal connection for the high-side MOSFET source and low-side MOSFET

drain.

23

FS

Frequency Setting Pin.

28

PVDD

Power Supply for gate driver of bottom MOSFET.

1, 3

NC

No Connect.