UCC38083PW Datasheet, PDF (1/26 Pages) Texas Instruments – 8-PIN CURRENT MODE PUSH-PULL PWM CONTROLLERS WITH PROGAMMABLE SLOPE COMPENSATION

UCC28083, UCC28084, UCC28085, UCC28086
UCC38083, UCC38084, UCC38085, UCC38086
SLUS488E − SEPTEMBER 2002 − REVISED JULY 2009
8ĆPIN CURRENT MODE PUSHĆPULL PWM CONTROLLERS
WITH PROGRAMMABLE SLOPE COMPENSATION
FEATURES
D Programmable Slope Compensation
D Internal Soft-Start on the UCC38083/4
D Cycle-by-Cycle Current Limiting
D Low Start-Up Current of 120 µA and 1.5 mA
Typical Run Current
D Single External Component Oscillator
Programmable from 50 kHz to 1 MHz
D High-Current Totem-Pole Dual Output Stage
Drives Push-Pull Configuration with 1-A Sink
and 0.5-A Source Capability
D Current Sense Discharge Transistor to
Improve Dynamic Response
D Internally Trimmed Bandgap Reference
D Undervoltage Lockout with Hysteresis
BASIC APPLICATION
V _IN
VDD
UCC3808x
CTRL OUTA
RT
OUTB
ISET
CS
RT
R _SET
GND
POWER
TRANSFORMER
RF
CF
RS
FEEDBACK
APPLICATIONS
D High-Efficiency Switch-Mode Power Supplies
D Telecom dc-to-dc Converters
D Point-of-Load or Point-of-Use Power Modules
D Low-Cost Push-Pull and Half-Bridge
Applications
DESCRIPTION
The UCC38083/4/5/6 is a family of BiCMOS pulse width
modulation (PWM) controllers for dc-to-dc or off-line
fixed-frequency current-mode switching power
supplies. The dual output stages are configured for the
push-pull topology. Both outputs switch at half the
oscillator frequency using a toggle flip-flop. The dead
time between the two outputs is typically 110 ns, limiting
each output’s duty cycle to less than 50%.
The new UCC3808x family is based on the UCC3808A
architecture. The major differences include the addition
of a programmable slope compensation ramp to the CS
signal and the removal of the error amplifier. The current
flowing out of the ISET pin through an external resistor
is monitored internally to set the magnitude of the slope
VOUT
compensation function. This device
internal discharge transistor from the
also includes an
CS pin to ground,
which is activated at each clock cycle after the pulse is
terminated. This discharges any filter capacitance on
the CS pin during each cycle and helps minimize filter
capacitor values and current sense delay.
The UCC38083 and the UCC38084 devices have a
typical soft-start interval time of 3.5 ms while the
UCC38085 and the UCC38086 has less than 100 µs for
applications where internal soft-start is not desired.
The UCC38083 and the UCC38085 devices have the
turn-on/off thresholds of 12.5 V / 8.3 V, while the
UCC38084 and the UCC38086 has the turn-on/off
thresholds of 4.3 V / 4.1 V. Each device is offered in 8-pin
TSSOP (PW), 8-pin SOIC (D) and 8-pin PDIP (P)
packages.
UDG−01080
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of 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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