UCC28083, UCC28084, UCC28085, UCC28086
UCC38083, UCC38084, UCC38085, UCC38086
SLUS488E − SEPTEMBER 2002 − REVISED JULY 2009
8 PIN CURRENT MODE PUSH PULL PWM CONTROLLERS
WITH PROGRAMMABLE SLOPE COMPENSATION
FEATURES
APPLICATIONS
D
D
D
D
D
D
D
D
D
Programmable Slope Compensation
Internal Soft-Start on the UCC38083/4
Cycle-by-Cycle Current Limiting
Low Start-Up Current of 120
µA
and 1.5 mA
Typical Run Current
Single External Component Oscillator
Programmable from 50 kHz to 1 MHz
High-Current Totem-Pole Dual Output Stage
Drives Push-Pull Configuration with 1-A Sink
and 0.5-A Source Capability
Current Sense Discharge Transistor to
Improve Dynamic Response
Internally Trimmed Bandgap Reference
Undervoltage Lockout with Hysteresis
D
D
D
D
High-Efficiency Switch-Mode Power Supplies
Telecom dc-to-dc Converters
Point-of-Load or Point-of-Use Power Modules
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
V OUT
compensation function. This device also includes an
internal discharge transistor from the 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.
BASIC APPLICATION
V IN
POWER
TRANSFORMER
VDD
UCC3808x
CTRL
OUTA
RT
OUTB
RF
ISET
RT
R SET
GND
CS
CF
RS
FEEDBACK
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.
Copyright
2002−2009, Texas Instruments Incorporated
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