Current-Mode PWM Controller - UC3843

UC3843 (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

View more

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)
Special Features
Rating
Operating Temperature Range (C)
Pin/Package
Approx. Price (US$)
UC3843 LM5021 LM5021-Q1 UC1843 UC2843 UC3842 UC3845
Boost
Buck
Buck-Boost
Flyback
Forward   
Boost
Flyback   
Flyback    Boost
Flyback
Forward   
Boost
Buck
Buck-Boost
Flyback
Forward   
Boost
Buck
Buck-Boost
Flyback
Forward   
Boost
Buck
Buck-Boost
Flyback
Forward   
Peak Current Mode        Current    Peak Current Mode    Peak Current Mode    Peak Current Mode   
9    8    8    7.6    9    17    9   
400    30    30    30    400    400    400   
500        500    500    500    500   
8.4/7.6    20/7.25    20/7.25    8.4/7.6    8.4/7.6    16/10    8.4/7.6   
100    80    80    100    100    100    50   
1    0.3    0.3    1    1    1    1   
Error Amplifier
Multi-topology   
SSR
DCM
CCM
Frequency Synchronization
Smart Meters Compatible
Audio Compatible
Motor Drive Compatible
Power Delivery Compatible   
SSR
DCM
CCM
Frequency Synchronization
Automotive   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Error Amplifier
Multi-topology   
Catalog    Catalog    Automotive    Military    Military    Catalog    Catalog   
0 to 70    -40 to 125    -40 to 125    -55 to 125    -40 to 85    0 to 70    0 to 70   
14SOIC
8PDIP
8SOIC   
8PDIP
8VSSOP   
8VSSOP    20LCCC
8CDIP   
14SOIC
8PDIP
8SOIC   
14SOIC
8PDIP
8SOIC   
14SOIC
8PDIP
8SOIC   
0.42 | 1ku    0.50 | 1ku    0.59 | 1ku        0.42 | 1ku    0.42 | 1ku   

Other qualified versions of UC3843

Version Part Number Definition
Military UC1843 QML certified for Military and Defense Applications

WEBENCH® Designer UC3843

 AC  DC  
AC Frequency  60 Hz  50 Hz
Use Isolated Output?
  Min   Max Range
VinRMS  V 15.00 to 480.00V
Vout  V 3.3 to 50.0V
Iout  A ≤ 20.0A
Ambient Temp  °C 0 to 70°C