UCC28230 Datasheet, PDF (1/7 Pages) Texas Instruments – Advanced PWM Controller For Bus Converters

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Advanced PWM Controller For Bus Converters
UCC28230
UCC28231
SLUS814 – FEBRUARY 2008
FEATURES
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• Programmable, Load Dependent, Off-Time
Control
• Frequency Controlled Start Up Allows Small
Output Inductor, Low Ripple and Constant
Current Start with Large Output Capacitor
• Two 0.2-A Push-Pull Outputs Provide Matched
Control Signals D to External Drivers
• Two Additional 1- D Outputs for Optimal Use
of Self-Driven or Control Driven Synchronous
Rectifiers
• Unregulated, Fixed Volt-Second or Fixed
Frequency Modes set by User
• Two, 1.5% Overall Accuracy Reference Voltage
Options: 5-V for UCC28230 and 3.3-V for
UCC28231
• Resistor Programmable Switching Frequency
up to 1 MHz
• Cycle-by-Cycle Current Limit Allows Parallel
Operation with Droop Based Current Sharing
• Single External Capacitor sets Soft-Start and
Over Current Hiccup Mode Parameters with
Restart
• Severe Short Circuit Hiccup with Restart or
Latch-Off Protection Option by External
Resistor
• Input Under Voltage Lock Out
• Thermal Shutdown
• Thermally Enhanced 3 mm x 2 mm SON-12
and TSSOP-14 Package Options
APPLICATIONS
• Intermediate Bus Isolated Converters
• DC-to-DC Transformers
DESCRIPTION
The UCC28230, UCC28231 PWM bus controllers are
optimized for use in high efficiency, high power
density, unregulated intermediate bus converters.
Topologies include push-pull, half-bridge and
full-bridge. External drivers, such as 120-V
high-side/low-side driver UCC27200, can be used
with this controller.
Low cost, small size and highly efficient solutions are
achieved by innovations such as:
• Start-up frequency control circuit allowing small
output inductor and start with large intermediate
bus capacitance.
• Load dependent off-time control set by user.
Additional 1-D control outputs can be used for
primary winding clamping in self-driven output
synchronous rectifier applications or as drive signals
for the control-driven synchronous rectifier.
Cycle-by-cycle current limit prevents overstresses of
converter. If the over current condition causes less
than 80% duty cycle at the output, then after
programmable time the controller proceeds into
periodical shutdown and restart hiccup mode.
The UCC28230 provides 5 V, and the UCC28231
provides 3.3-V precision reference voltages with 1.5%
overall accuracy and 10-mA output current. This
reference voltage can be used to supply
housekeeping circuit and/or microcontroller. The
precision reference voltage can also be used for
accurate setting of system parameters.
Other features include under-voltage lockout, thermal
shutdown, programmable soft-start, over-current
hiccup mode and short circuit protection with internal
restart (by default) or latch-off mode by using an
external resistor.
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Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCT PREVIEW information concerns products in the
formative or design phase of development. Characteristic data and
other specifications are design goals. Texas Instruments reserves
the right to change or discontinue these products without notice.
Copyright © 2008, Texas Instruments Incorporated