UCC28251 Datasheet, PDF (1/54 Pages) Texas Instruments – Advanced PWM Controller With Pre-Bias Operation

UCC28251
www.ti.com
SLUSBD8D – FEBRUARY 2013 – REVISED APRIL 2013
Advanced PWM Controller With Pre-Bias Operation
Check for Samples: UCC28251
FEATURES
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• Pre-biased Startup
• Synchronous Rectifier Control Outputs with
Programmable Delays (Including Zero Delay
Support)
• Voltage Mode Control with Input Voltage Feed-
Forward or Current Mode Control
• Primary or Secondary-Side Control
• 3.3-V, 1.5% Accurate Reference Output
• Lower Minimum Operating Frequency
• 1% Accurate Cycle-by-Cycle Over Current
Protection with Matched Duty Cycle Outputs
• Programmable Soft-Start and Hiccup Restart
Timer
• Thermally Enhanced 4-mm x 4-mm QFN-20
Package and 20-pin TSSOP Package
APPLICATIONS
• Half-Bridge, Full-Bridge, Interleaved Forward,
and Push-Pull Isolated Converters
• Telecom and Data-com Power
• Wireless Base Station Power
• Server Power
• Industrial Power Systems
DESCRIPTION
The UCC28251 PWM controller is designed for high
power density applications that may have stringent
pre-biased startup requirements. The UCC28251’s
integrated synchronous rectifier control outputs target
high efficiency and high performance topologies such
as half-bridge, full-bridge, interleaved forward, and
push-pull. The UCC27210 half bridge drivers and
UCC2752x MOSFET drivers used in conjunction with
the UCC28251 provide a complete power converter
solution.
The UCC28251 is a functional variant of the
UCC28250 PWM Controller. While the same basic
functionality of the UCC28250 is largely maintained,
the UCC28251 is designed to enhance performance
in both offline, 400-V input DC-to-DC applications and
48-V input full-bridge or half-bridge applications.
Externally programmable soft-start, used in
conjunction with an internal pre-biased startup circuit,
allows the controller to gradually reach a steady-state
operating point under all output conditions. The
UCC28251 can be configured for primary or
secondary-side control and either voltage or current
mode control can be implemented.
The oscillator operates at frequencies up to 1.8 MHz,
and can be synchronized to an external clock. Input
voltage feedforward, cycle-by-cycle current limit, and
a programmable hiccup timer allow the system to
stay within a safe operation range. Input voltage,
output voltage and temperature protection can be
implemented. Dead time between primary-side switch
and secondary-side synchronous rectifiers can be
independently programmed.
Simple Application Diagram (400-V_IN DC-to-DC Converter)
Secondary
UCC28251
VREF
RAMP
OUTA
OUTB
RT
SRA
SS
SRB
VSENSE
FB
GND
Isolation
Primary
400 V
700-V Driver
HI
HO
LI
LO
Secondary
UCC 2752 x
Secondary
Not Shown : PS, SP, HICC, VDD , EA+, EN AND ILIM
VOUT
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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 the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2013, Texas Instruments Incorporated