application
INFO
available
UCC1895
UCC2895
UCC3895
BiCMOS Advanced Phase Shift PWM Controller
FEATURES
•
Programmable Output Turn-on Delay
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DESCRIPTION
The UCC3895 is a phase shift PWM controller that implements control of a
full-bridge power stage by phase shifting the switching of one half-bridge
Adaptive Delay Set
with respect to the other. It allows constant frequency pulse-width modula-
Bidirectional Oscillator Synchronization tion in conjunction with resonant zero-voltage switching to provide high effi-
ciency at high frequencies. The part can be used either as a voltage mode
Capability for Voltage Mode or Current
or current mode controller.
Mode Control
While the UCC3895 maintains the functionality of the UC3875/6/7/8 family
Programmable Soft Start/Soft Stop
and UC3879, it improves on that controller family with additional features
and Chip Disable via a Single Pin
such as enhanced control logic, adaptive delay set, and shutdown capabil-
ity. Since it is built in BCDMOS, it operates with dramatically less supply
0% to 100% Duty Cycle Control
current than it’s bipolar counterparts. The UCC3895 can operate with a
7MHz Error Amplifier
maximum clock frequency of 1MHz.
Operation to 1MHz
The UCC3895 and UCC2895 are offered in the 20 pin SOIC (DW) pack-
age, 20 pin PDIP (N) package, 20 pin TSSOP (PW) package, and 20 pin
PLCC (Q). The UCC1895 is offered in the 20 pin CDIP (J) package, and 20
pin CLCC package (L).
•
Low Active Current Consumption
(5mA Typical @ 500kHz)
•
Very Low Current Consumption
During Undervoltage Lock-out
(150mA typical)
SIMPLIFIED APPLICATION DIAGRAM
UCC3895
1
EAN
EAP
20
7
Q1
V
OUT
2
EAOUT
SS/DISB
19
3
RAMP
OUTA
18
4
REF
OUTB
17
A
C
5
GND
PGND
16
V
IN
V
BIAS
6
SYNC
VCC
15
7
CT
OUTC
14
B
D
8
RT
OUTD
13
9
DELAB
CS
12
10
DELCD
ADS
11
UDG-98139
SLUS157B - DECEMBER 1999 - REVISED JANUARY 2001
TI [ TEXAS INSTRUMENTS ]
