Current-Mode PWM Controller - UC2842

UC2842 (ACTIVE)

Current-Mode PWM Controller

 

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.

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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Parametrics Compare all products in PWM and Resonant Controller

 
Topology
Control Method
Vin (Min) (V)
Vin (Max) (V)
Frequency (Max) (kHz)
UVLO Thresholds On/Off (V)
Duty Cycle (Max) (%)
Gate Drive (Typ) (A)
Features
Rating
Operating Temperature Range (C)
Pin/Package
UC2842 UC2843 UC2844 UC2845
Boost
Buck
Buck-Boost
Flyback
Forward   
Boost
Buck
Buck-Boost
Flyback
Forward   
Boost
Buck
Flyback
Forward   
Boost
Buck
Flyback
Forward   
Peak Current Mode    Peak Current Mode    Peak Current Mode    Peak Current Mode   
16    8.4    16    8.4   
400    400    400    400   
500    500    500    500   
16/10    8.4/7.6    16/10    8.4/7.6   
100    100    50    50   
1    1    1    1   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Catalog    Catalog    Catalog    Catalog   
-40 to 85    -40 to 85    -40 to 85    -40 to 85   
14SOIC
8PDIP
8SOIC   
14SOIC
8PDIP
8SOIC   
14SOIC
8PDIP
8SOIC   
14SOIC
8PDIP
8SOIC   

WEBENCH® Designer UC2842

 AC  DC  
AC Frequency  60 Hz  50 Hz
Use Isolated Output?
  Min   Max Range
VinRMS  V 20.00 to 480.00V
Vout  V 3.3 to 50.0V
Iout  A ≤ 20.0A
Ambient Temp  °C -40 to 85°C