MIC2166_1009 Datasheet, PDF (3/28 Pages) Micrel Semiconductor – Adaptive On-Time DC-DC Controller Hyper Speed Control™ Family

Micrel, Inc.
MIC2166
Pin Description (Continued)
Pin
Number
9
10
EP
Pin Name
SW
BST
GND
Pin Function
Switch Node (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.
Current Sense (Input): SW pin also senses the current by monitoring the voltage across the low-side
MOSFET during OFF-time. The current sensing is necessary for short circuit protection. In order to
sense the current accurately, connect the low-side MOSFET drain to SW using a Kelvin connection.
Boost (Output): Bootstrapped voltage to the high-side N-channel 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 at BST pin can slow down the turn-on time of high-side
N-Channel MOSFETs.
Thermal Pad and Signal ground. GND is the ground path for VDD and the control circuitry. The loop for
the signal ground should be separate from the power ground (PGND) loop.
September 2010
3
M9999-092410-C