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Synchronous Rectifier Driver
DESCRIPTION
These two families of high speed drivers are designed to provide drive
waveforms for complementary switches. Complementary switch configura-
tions are commonly used in synchronous rectification circuits and active
clamp/reset circuits, which can provide zero voltage switching. In order to
facilitate the soft switching transitions, independently programmable delays
between the two output waveforms are provided on these drivers. The de-
lay pins also have true zero voltage sensing capability which allows imme-
diate activation of the corresponding switch when zero voltage is applied.
These devices require a PWM-type input to operate and can be interfaced
with commonly available PWM controllers.
In the UC1714 series, the AUX output is inverted to allow driving a
p-channel MOSFET. In the UC1715 series, the two outputs are configured
in a true complementary fashion.
BLOCK DIAGRAM
2
PWR
50ns 鈥?00ns
INPUT
6
TIMER
S
Q
R
V
REF
50ns 鈥?00ns
TIMER
S
Q
T2
5
R
V
REF
UC1714
ONLY
T1
7
4
1
V
CC
5V
LOGIC
GATES
TIMER
REF
AUX
VCC
BIAS
ENBL 3V
GND
3
1.4V
ENBL
8
ENABLE
GND
Note: Pin numbers refer to J, N and D packages.
UDG-99028
SLUS170A - FEBRUARY 1999 - REVISED JANUARY 2002