UCC2888 Datasheet, PDF (1/9 Pages) Texas Instruments – OFF-LINE POWER SUPPLY CONTROLLER

www.ti.com
UCC2888
UCC3888
SLUS159B – MARCH 1997 – REVISED JUNE 2007
OFF-LINE POWER SUPPLY CONTROLLER
FEATURES
• Transformerless Off-Line Power Supply
• Wide 100-VDC to 400-VDC Allowable Input
Range
• Fixed 5-VDC or Adjustable Low-Voltage
Output
• Output Sinks 200 mA, Sources 150 mA Into a
MOSFET Gate
• Uses Low-Cost SMD Inductors
• Short Circuit Protected
• Optional Isolation Capability
TYPICAL APPLICATION
100-400 V
DESCRIPTION
The UCC3888 controller is optimized for use as an
off-line, low-power, low-voltage, regulated bias
supply. The unique circuit topology utilized in this
device can be visualized as two cascaded flyback
converters, each operating in the discontinuous
mode, both driven from a single external power
switch. The significant benefit of this approach is the
ability to achieve voltage conversion ratios as high
as 400 V to 2.7 V with no transformer and low
internal losses.
The control algorithm utilized by the UCC3888 sets
the switch on time inversely proportional to the input
line voltage and sets the switch off time inversely
proportional to the output voltage. This action is
automatically controlled by an internal feedback loop
and reference. The cascaded configuration allows a
voltage conversion from 400 V to 2.7 V to be
achieved with a switch duty cycle of 7.6%. This
topology also offers inherent short circuit protection
because as the output voltage falls to zero, the
switch-off time approaches infinity.
The output voltage is set internally to 5 V. It can be
programmed for other output voltages with two
external resistors. An isolated version can be
achieved with this topology as described further in
Unitrode Application Note U-149.
5-V
Note: This device incorporates patented technology used under license from Lambda Electronics, Inc.
UDG-96013
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 the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 1997–2007, Texas Instruments Incorporated