(ACTIVE) PWM Controller


Functional Diagram


The TL494 device incorporates all the functions required in the construction of a pulse-width-modulation (PWM) control circuit on a single chip. Designed primarily for power-supply control, this device offers the flexibility to tailor the power-supply control circuitry to a specific application.

The TL494 device contains two error amplifiers, an on-chip adjustable oscillator, a dead-time control (DTC) comparator, a pulse-steering control flip-flop, a 5-V, 5%-precision regulator, and output-control circuits.

The error amplifiers exhibit a common-mode voltage range from –0.3 V to VCC – 2 V. The dead-time control comparator has a fixed offset that provides approximately 5% dead time. The on-chip oscillator can be bypassed by terminating RT to the reference output and providing a sawtooth input to CT, or it can drive the common circuits in synchronous multiple-rail power supplies.

The uncommitted output transistors provide either common-emitter or emitter-follower output capability. The TL494 device provides for push-pull or single-ended output operation, which can be selected through the output-control function. The architecture of this device prohibits the possibility of either output being pulsed twice during push-pull operation.

The TL494C device is characterized for operation from 0°C to 70°C. The TL494I device is characterized for operation from –40°C to 85°C.


  • Complete PWM Power-Control Circuitry
  • Uncommitted Outputs for 200-mA Sink or
    Source Current
  • Output Control Selects Single-Ended or
    Push-Pull Operation
  • Internal Circuitry Prohibits Double Pulse at
    Either Output
  • Variable Dead Time Provides Control Over
    Total Range
  • Internal Regulator Provides a Stable 5-V Reference Supply With 5% Tolerance
  • Circuit Architecture Allows Easy Synchronization

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Topology Boost^Buck^Flyback^Forward^Full-Bridge^Half-Bridge^Push-Pull    
Control method Voltage    
VCC (Min) (V) 7    
VCC (Max) (V) 40    
Frequency (Max) (kHz) 300    
UVLO thresholds on/off (V) N/A    
Duty cycle (Max) (%) 45    
Gate drive (Typ) (A) 0.2    
Features Adjustable Switching Frequency^Dead Time Control^Error Amplifier^Multi-topology    
Rating Catalog    
Operating temperature range (C) -40 to 85^0 to 70    
Package Group PDIP|16^SOIC|16^SO|16^TSSOP|16    
Package size: mm2:W x L (PKG) See datasheet (PDIP)^16SO: 80 mm2: 7.8 x 10.2 (SO|16)^16SOIC: 59 mm2: 6 x 9.9 (SOIC|16)^16TSSOP: 22 mm2: 4.4 x 5 (TSSOP|16)    

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Datasheet (1)

Application notes (6)

Selection guides (1)

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