UC3842 product image


TI [Texas Instruments]
FAIRCHILD [Fairchild Semiconductor]
PHILIPS [NXP Semiconductors]

The  UC3842  is available in an 8-Pin mini-DIP the necessary features to implement off-line, fixed-frequency current-mode control schemes with a minimal external parts count. This technique results in improved line regulation, enhanced load response characteristics, and a simpler, easier to design control loop. Topological advantages include inherent pulse-by-pulse current limiting.


Protection circuitry includes built-in undervoltage lock-out and current limiting. Other features include fully-latched operation, a 1% trimmed bandgap reference, and start-up current less than 1mA.


These devices feature a totem-pole output designed to source and sink high peak current from a capacitive load, such as the gate of a power MOSFET. Consistent with N-channel power devices, the output is low in the OFF-state.
UC3842 Features
  • •Low start-up current (31mA)
  • •Automatic feed-forward compensation
  • •Pulse-by-pulse current limiting
  • •Enhanced load response characteristics
  • •Undervoltage lock-out with hysteresis
  • •Double pulse suppression
  • •High current totem-pole output
  • •Internally-trimmed bandgap reference
  • •400kHz operation, guaranteed min
UC3842 Applications


  • •Off-line switched mode power supplies
  • •DC-to-DC converters UC3842
Supply voltage (low impedance source) VCC30V
Output current IOUT±1A
Output energy (capacitive load)5uJ
Analog inputs (Pin 2, Pin 3)-0.3 to 6.3V
Power dissipation at TA370°C PD1W
Storage temperature range TSTG-65 to +150°C
UC3842 Replacement Parts
UC3842 Price
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