MIC4100 Datasheet, PDF (17/18 Pages) Micrel Semiconductor – 100V Half Bridge MOSFET Drivers

Micrel, Inc.
MIC4100/1
The circuit is configured as a synchronous buck power
stage. The high-side MOSFET drain connects to the input
supply voltage (drain) and the source connects to the
switching node. The low-side MOSFET drain connects to
the switching node and its source is connected to ground.
The buck converter output inductor (not shown) would
connect to the switching node. The high-side drive trace,
HO, is routed on top of its return trace, HS, to minimize
loop area and parasitic inductance. The low-side drive
trace LO is routed over the ground plane which minimizes
the impedance of that current path. The decoupling
capacitors, C_B and C_VDD are placed to minimize etch length
between the capacitors and their respective pins. This
close placement is necessary to efficiently charge
capacitor C_B when the HS node is low. All traces are
0.025” wide or greater to reduce impedance. Cin is used to
decouple the high current path through the MOSFETs.
Vin (FET Drain)
High-side FET
CIN
Low-side FET
HS Node
(switching node)
GND
Cvdd
CB
HS HO
HB
Vdd
GND
(FET Source)
MIC4100
LO
Vss
LI
HI
Figure 12
HO trace
March 2006
17
M9999-031506