UCC35701_13 Datasheet, PDF (1/24 Pages) Texas Instruments – Advanced Voltage Mode Pulse Width Modulator

application
INFO
available
Advanced Voltage Mode Pulse Width Modulator
UCC15701/2
UCC25701/2
UCC35701/2
FEATURES
DESCRIPTION
700kHz Operation
Integrated Oscillator/ Voltage Feed
Forward Compensation
Accurate Duty Cycle Limit
Accurate Volt-second Clamp
Optocoupler Interface
Fault Counting Shutdown
Fault Latch off or Automatic Shutdown
Soft Stop Optimized for Synchronous
Rectification
1A Peak Gate Drive Output
The UCC35701/UCC35702 family of pulse width modulators is intended for
isolated switching power supplies using primary side control. They can be
used for both off-line applications and DC/DC converter designs such as in
a distributed power system architecture or as a telecom power source.
The devices feature low startup current, allowing for efficient off-line start-
ing, yet have sufficient output drive to switch power MOSFETs in excess of
500kHz.
Voltage feed forward compensation is operational over a 5:1 input range
and provides fast and accurate response to input voltage changes over a
4:1 range. An accurate volt-second clamp and maximum duty cycle limit
are also featured.
Fault protection is provided by pulse by pulse current limiting as well as the
ability to latch off after a programmable number of repetitive faults has oc-
curred.
130mA Start-up Current
Two UVLO options are offered. UCC35701 family has turn-on and turn-off
750mA Operating Current
thresholds of 13V/9V and UCC35702 family has thresholds of 9.6V/8.8V.
The UCC35701/2 and the UCC25701/2 are offered in the 14 pin SOIC (D),
14 pin PDIP (N) or in 14 pin TSSOP (PW) packages. The UCC15701/2 is
offered in the 14 pin CDIP (J) package.
TYPICAL APPLICATION DIAGRAM
V_IN S UP P LY
VREF
R4
R5
CF
R_F
R1
R6
R2
VFF
R7
6
VDD 3
R3
7 RT
CT
UCC35701
10 CT
C1
9 VS CLAMP
11 S YNC
CS
14 SS
OUT 4
ILIM 2
1 COUNT
C3
12 VREF
P GND 5
R8
R10
C2
RCS
R8
RGND
8 FB
GND 13
R11
C5
R12
C6
V_OUT
R13
R14
C7
R15
SLUS293C - JANUARY 2000 - REVISED JUNE 2005
C6 ^V_OUT
C4
V_IN RETURN
UDG-98005-1