UCC3808 Datasheet, PDF (1/10 Pages) Texas Instruments – LOW POWER CURRENT MODE PUSH-PULL PWM

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UCC2808-1, UCC2808-2, UCC3808-1, UCC3808-2
LOW POWER CURRENT MODE PUSH-PULL PWM
D Dual Output Drive Stages in Push-Pull
Configuration
D 130-µA Typical Starting Current
D 1-mA Typical Run Current
D Operation to 1-MHz
D Internal Soft Start
D On Chip Error Amplifier With 2-MHz Gain
Bandwidth Product
D On Chip VDD Clamping
D Output Drive Stages Capable Of 500-mA
Peak Source Current, 1-A Peak Sink Current
description
SLUS168D – APRIL 1999 – REVISED AUGUST 2002
D OR N PACKAGE
(TOP VIEW)
COMP ¹
FB 2
CS 3
RC ₄
8 VDD
7 OUTA
6 ^OUTB
5 ^GND
OUTA
VDD
COMP
FB
PW PACKAGE
(TOP VIEW)
1
8
2
7
3
6
4
5
OUTB
GND
RC
CS
The UCC3808 is a family of BiCMOS push-pull, high-speed, low-power, pulse-width modulators. The UCC3808
contains all of the control and drive circuitry required for off-line or dc-to-dc fixed frequency current-mode switching
power supplies with minimal external parts count.
The UCC3808 dual output drive stages are arranged in a push-pull configuration. Both outputs switch at half the
oscillator frequency using a toggle flip-flop. The dead time between the two outputs is typically 60 ns to 200 ns
depending on the values of the timing capacitor and resistors, thus limiting each output stage duty cycle to less than
50%. (continued)
block diagram
FB
COMP
CS
2
1
3
OVERCURRENT
COMPARATOR
VDD OK
VDD–1 V
0.5 V
22 k Ω
0.75 V
2.0 V
2.2 V
S
Q
R
S
Q
R
VDD
VOLTAGE
REFERENCE
SOFT START
SLOPE = 1 V/ms
PEAK CURRENT
COMPARATOR
0.5 V
OSCILLATOR
1.2R
PWM
COMPARATOR
R
4
Note: Pinout shown is for SOIC and PDIP packages. TSSOP pinout is different.
RC
14 V
PWM
LATCH
S
Q
R
Q
T
Q
8 VDD
7 OUTA
6 OUTB
5 GND
UDG-02116
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of Texas Instruments
standard warranty. Production processing does not necessarily include
testing of all parameters.
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Copyright  2002, Texas Instruments Incorporated
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