Current Mode PWM Controller - UC3846

UC3846 (ACTIVE)

Current Mode PWM Controller

Description

The UC1846/7 family of control ICs provides all of the necessary features to implement fixed frequency, current mode control schemes while maintaining a minimum external parts count. The superior performance of this technique can be measured 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 capability, automatic symmetry correction for push-pull converters, and the ability to parallel "power modules" while maintaining equal current sharing.

Protection circuitry includes built-in under-voltage lockout and programmable current limit in addition to soft start capability. A shut-down function is also available which can initiate either a complete shutdown with automatic restart or latch the supply off.

Other features include fully latched operation, double pulse suppression, deadline adjust capability, and a ±1% trimmed bandgap reference.

The UC1846 features low outputs in the OFF state, while the UC1847 features high outputs in the OFF state.

Features

  • Automatic Feed Forward Compensation
  • Programmable Pulse-by-Pulse Current Limiting
  • Automatic Symmetry Correction in Push-pull Configuration
  • Enhanced Load Response Characteristics
  • Parallel Operation Capability for Modular Power Systems
  • Differential Current Sense Amplifier with Wide Common Mode Range
  • Double Pulse Suppression
  • 500mA (Peak) Totem-pole Outputs
  • ±1% Bandgap Reference
  • Under-voltage Lockout
  • Soft Start Capability
  • Shutdown Terminal
  • 500kHZ Operation

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Parametrics Compare all products in PWM and Resonant Controller

 
Topology
Control Method
Duty Cycle (Max) (%)
Frequency (Max) (kHz)
UVLO Thresholds On/Off (V)
Regulated Outputs (#)
Special Features
Rating
Operating Temperature Range (C)
Pin/Package
Approx. Price (US$)
UC3846 UC1846 UC2846
Boost
Buck
Flyback
Forward
Full-Bridge
Half-Bridge
Push-Pull    
Boost
Flyback
Forward
Full-Bridge
Half-Bridge
Push-Pull    
Boost
Flyback
Forward
Full-Bridge
Half-Bridge
Push-Pull    
Current     Current     Current    
50     50     50    
450     450     450    
7.7/6.95     7.7/6.95     7.7/6.95    
2     2     2    
Error Amplifier
Soft Start
Synchronization Pin    
Error Amplifier
Soft Start
Synchronization Pin    
Error Amplifier
Soft Start
Synchronization Pin    
Catalog     Military     Catalog    
0 to 70     -55 to 125     -40 to 85    
16PDIP
16SOIC
20PLCC    
16CDIP
20LCCC    
16PDIP
16SOIC
20PLCC    
1.60 | 1ku       1.70 | 1ku    

Other qualified versions of UC3846

Version Part Number Definition
Military UC1846 QML certified for Military and Defense Applications
Enhanced Product UC1846-EP Supports Defense, Aerospace and Medical Applications
Catalog UC3846M TI's standard catalog product
Space UC1846-SP Radiation tolerant, ceramic packaging and qualified for use in Space-based application
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