MIC2176 Datasheet, PDF (3/31 Pages) Micrel Semiconductor – Wide Input Voltage, Synchronous Buck

Micrel, Inc.
MIC2176
Pin Description (Continued)
Pin
Number
9
10
Pin Name
SW
BST
Pin Function
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.
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.
November 2010
3
M9999-111710-A