High Speed PWM Controller - UC3825

UC3825 (ACTIVE)

High Speed PWM Controller

Description

The UC1825 family of PWM control ICs is optimized for high frequency switched mode power supply applications. Particular care was given to minimizing propagation delays through the comparators and logic circuitry while maximizing bandwidth and slew rate of the error amplifier. This controller is designed for use in either current-mode or voltage mode systems with the capability for input voltage feed-forward.

Protection circuitry includes a current limit comparator with a 1V threshold, a TTL compatible shutdown port, and a soft start pin which will double as a maximum duty cycle clamp. The logic is fully latched to provide jitter free operation and prohibit multiple pulses at an output. An under-voltage lockout section with 800mV of hysteresis assures low start up current. During under-voltage lockout, the outputs are high impedance.

These devices feature totem pole outputs designed to source and sink high peak currents from capacitive loads, such as the gate of a power MOSFET. The on state is designed as a high level.

Features

  • Compatible with Voltage or Current Mode Topologies
  • Practical Operation Switching Frequencies to 1MHz
  • 50ns Propagation Delay to Output
  • High Current Dual Totem Pole Outputs (1.5A Peak)
  • Wide Bandwidth Error Amplifier
  • Fully Latched Logic with Double Pulse Suppression
  • Pulse-by-Pulse Current Limiting
  • Soft Start / Max. Duty Cycle Control
  • Under-Voltage Lockout with Hysteresis
  • Low Start Up Current (1.1mA)

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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$)
UC3825 UC1825 UC2825
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
Voltage    
Current     Current    
50     50     50    
1000     1000     1000    
9.2/8.4     9.2/8.4     9.2/8.4    
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
20PLCC
16SOIC    
16CDIP
16CFP
20LCCC    
16PDIP
16SOIC
20PLCC    
1.68 | 1ku       1.76 | 1ku    

Other qualified versions of UC3825

Version Part Number Definition
Military UC1825 QML certified for Military and Defense Applications
Catalog UC3825M TI's standard catalog product
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