Micrel, Inc.

MIC2176

November 2010

3

M9999-111710-A

Pin Description (Continued)

Pin

Number

Pin Name

Pin Function

9

SW

Switch Node and Current-Sense input (Input): High current output driver return. The SW pin connects

directly to the switch node. Due to the high-speed switching on this pin, the SW pin should be routed

away from sensitive nodes. The SW pin also senses the current by monitoring the voltage across the

low-side MOSFET during OFF time. In order to sense the current accurately, connect the low-side

MOSFET drain to the SW pin using a Kelvin connection.

10

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. Adding a small resistor in series with the BST pin can slow

down the turn-on time of high-side N-Channel MOSFETs.