Buffered Power Half-Bridge
Functional Block Diagram
IN
AAT4900
CLK
Control Logic
and
Shoot-Through
Protection
LX
EN
GND
Typical Applications
DC/DC Converter
The most common AAT4900 applications include a
DC/DC converter output power stage and a MOS-
FET gate drive buffer.
Figure 1 shows a common configuration when used
as a DC/DC converter power stage with synchro-
nous rectification. The enable pin can be used to
V
IN
= 2.0 to 5.5V
force the LX output to a high impedance state under
light load conditions. This enables the output induc-
tor to operate in discontinuous conduction mode
(DCM), improving efficiency under light load condi-
tions. The body diode associated with the low side
switching device gives the AAT4900 inductive
switching capability, clamping the LX node at a
diode drop below GND during the break-before-
make time.
IN
EN
DC / DC
Controller
AAT4900
CLK
GND
GND
LX
+
V
OUT
= 0 to V
IN
I
OUT
= 0 to 1A
-
Figure 1: AAT4900 DC/DC Converter Power Stage.
4900.2006.05.1.3
7
AAT [ ADVANCED ANALOG TECHNOLOGY, INC. ]
