UC3842

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Single ended 500KHz current mode PWM controller with 16V/10V UVLO 100% duty cycle, 0C to 70C

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Product details

Parameters

Topology Boost, Buck, Buck-Boost, Flyback, Forward Control method Peak Current Mode VCC (Min) (V) 16 VCC (Max) (V) 28 Duty cycle (Max) (%) 100 UVLO thresholds on/off (V) 16/10 Frequency (Max) (kHz) 500 Operating temperature range (C) 0 to 70 Gate drive (Typ) (A) 1 Features Adjustable Switching Frequency, Current Limiting, Dead Time Control, Error Amplifier, Multi-topology 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 SOIC (D) 14 52 mm² 8.65 x 6 open-in-new Find other PWM controllers & resonant controllers

Features

  • Optimized for off-line and DC-to-DC converters
  • Low start-up current (< 1 mA)
  • Automatic feedforward compensation
  • Pulse-by-pulse current limiting
  • Enhanced load-response characteristics
  • Undervoltage lockout with hysteresis
  • Double-pulse suppression
  • High-current totem-pole output
  • Internally trimmed bandgap reference
  • Up to 500-kHz operation
  • Error amplifier with low output resistance

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Description

The UCx84x series of control integrated circuits provide the features that are necessary to implement off-line or DC-to-DC fixed-frequency current-mode control schemes, with a minimum number of external components. The internally implemented circuits include an undervoltage lockout (UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator that also provides current-limit control, and a totem-pole output stage that is designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state.

The UCx84x family offers a variety of package options, temperature range options, choice of maximum duty cycle, and choice of turnon and turnoff thresholds and hysteresis ranges. Devices with higher turnon or turnoff hysteresis are ideal choices for off-line power supplies, while the devices with a narrower hysteresis range are suited for DC-DC applications. The UC184x devices are specified for operation from –55°C to 125°C, the UC284x series is specified for operation from –40°C to 85°C, and the UC384x series is specified for operation from 0°C to 70°C.

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Technical documentation

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Type Title Date
* Datasheet UCx84x Current-Mode PWM Controllers datasheet (Rev. F) Apr. 28, 2020
Application notes Understanding Inverting Buck-Boost Power Stages in Switch Mode Power Supplies (Rev. B) Mar. 12, 2019
Technical articles When should you use PWM controllers? Dec. 02, 2016
Application notes UCC38C42 Family of High-Speed BiCMOS Current-Mode PWM Controllers Feb. 07, 2002
Application notes Conditioning a Switch-mode Power Supply Current Signal Using TI Op Amps Mar. 23, 2000
Application notes DN-26 UC3842A Low-Cost Start-up and Fault Protection Circuit Sep. 05, 1999
Application notes DN-27 UC1842/UC1842A Family - Summary of Functional Differences Sep. 05, 1999
Application notes DN-40 The Effects of Oscillator Discharge Current Variations on Maximum Duty Sep. 05, 1999
Application notes DN-42A Design Considerations for Transitioning from UC3842 to the New UCC3802 Sep. 05, 1999
Application notes DN-62 Switching Power Supply Topology Voltage Mode vs. Current Mode Sep. 05, 1999
Application notes DN-65 Considerations in Powering BiCMOS ICs Sep. 05, 1999
Application notes DN-89 Comparing the UC3842, UCC3802, and UCC3809 Primary Side PWM Controllers Sep. 05, 1999
Application notes U-100A UC3842/3/4/5 Provides Low-Cost Current-Mode Control Sep. 05, 1999
Application notes U-111, Practical Considerations in Current Mode Power Supplies Sep. 05, 1999
Application notes Understanding Boost Power Stages In Switchmode Power Supplies Mar. 04, 1999
Application notes Understanding Buck Power Stages In Switchmode Power Supplies Mar. 04, 1999

Design & development

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Design tools & simulation

SIMULATION MODELS Download
SLUM522.ZIP (4 KB) - PSpice Model
SIMULATION MODELS Download
SLVM049.ZIP (101 KB) - PSpice Model

CAD/CAE symbols

Package Pins Download
PDIP (P) 8 View options
SOIC (D) 14 View options
SOIC (D) 8 View options

Ordering & quality

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