Product details


Topology Flyback Control method Feedforward, Voltage VCC (Min) (V) 8.6 VCC (Max) (V) 9.3 Duty cycle (Max) (%) 55 UVLO thresholds on/off (V) 8.4/6.3 Frequency (Max) (kHz) 250 Operating temperature range (C) 0 to 70 Gate drive (Typ) (A) 0.2 Features Error Amplifier, Soft Start Rating Catalog open-in-new Find other PWM controllers & resonant controllers

Package | Pins | Size

PDIP (P) 8 93 mm² 9.81 x 9.43 SOIC (D) 8 19 mm² 3.91 x 4.9 open-in-new Find other PWM controllers & resonant controllers


  • Transformerless Off-line Applications
  • Ideal Primary-side Bias Supply
  • Efficient BiCMOS Design
  • Wide Input Range
  • Fixed or Adjustable Low Voltage Output
  • Uses Low Cost SMD Inductors
  • Short Circuit Protected
  • Optional Isolation Capability

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The UCC1889 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, and both driven from a single external power switch. The significant benefit of this approach is the ability to achieve voltage conversion ratios of 400V to 12V with no transformer and low internal losses.

The control algorithm utilized by the UCC1889 is to force the switch on time to be inversely proportional to the input line voltage while the switch off time is made 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 400V to 12V to be achieved with a switch duty cycle greater than 10%. This topology also offers inherent short circuit protection since as the output voltage falls to zero, the switch off time approaches infinity.

The output voltage can be easily set to 12V or 18V. Moreover, it can be programmed for other output voltages less than 18V with a few additional components. An isolated version can be achieved with this topology as described further in Unitrode Application Note U-149.

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Technical documentation

= Top documentation for this product selected by TI
No results found. Please clear your search and try again. View all 5
Type Title Date
* Datasheet Off-line Power Supply Controller datasheet (Rev. A) Feb. 20, 2003
Selection guides Power Management Guide 2018 (Rev. R) Jun. 25, 2018
User guides Off-Line Low-Voltage Power Supply Evaluation Module UCC3889EVM-001 for TMS320C24 Dec. 12, 2001
Application notes DN-59A UCC3889 Bias Supply Controller EVM Kit - Schematic Sep. 05, 1999
Application notes U-149 Elegantly Simple Off-Line Bias Supply for Very Low Power Applications Sep. 05, 1999

Design & development

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Reference designs

PFC Non-Isolated Flyback 390V@2.56A and 12V@250mA for Blower PSU
PMP2552 — The PMP2552 is a power factor corrected 1KW Boost converter. It takes advantage of the continuous conduction mode inductor's current to reduce the conducted emissions while maintaining simplicity with a 8-pin controller. A small auxiliary power supply provides the 12V for the housekeeping and is (...)
3.6W Non-Isolated PSU
PMP4710 — Typical Bias supply connected directly off-line or to a 400V PFC voltage: simple way to generate 12V @ 300mA from hight voltage.
Design files

CAD/CAE symbols

Package Pins Download
PDIP (P) 8 View options
SOIC (D) 8 View options

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