Tl494 Circuit Diagram ★

TL494 Pulse‑Width Modulation (PWM) Controller — Overview and Example Circuits

What is the TL494?

The TL494 is a versatile, fixed‑frequency PWM controller originally designed for switching power supplies. It integrates the core functions needed to build regulated DC–DC converters: an error‑amplifier section, an internal oscillator, a dead‑time control input, a pulse‑width modulator with a comparator, an output‑transistor driver stage, and an overcurrent/feedback control pin. Its flexibility makes it suitable for flyback, forward, push‑pull, half‑bridge, and SEPIC topologies as well as simple switching regulators.

The TL494 is a fixed-frequency, Pulse Width Modulation (PWM) control circuit. Its primary job is to monitor an output voltage and adjust the "on-time" of its switching transistors to keep that voltage rock-steady. Key Features: tl494 circuit diagram

Circuit Diagram (Description):

  1. Oscillator: Connect CT (pin 5) to GND via 10nF. Connect RT (pin 6) to REF (pin 14) via 10kΩ. This sets frequency ≈ 1.1 / (RT * CT) ≈ 10 kHz.
  2. Dead-Time Control: Connect DTC (pin 4) to GND via a 1kΩ resistor (minimum dead time).
  3. Output Mode: Connect OUT CTRL (pin 13) to GND for single-ended output (both transistors in parallel).
  4. Feedback: Connect a potentiometer wiper to pin 3 (Feedback). One end of the pot to REF (5V), other end to GND. This varies duty cycle.
  5. Outputs: Short C1 (pin 8) and C2 (pin 11) together, then connect to +VCC through a pull-up resistor (1kΩ). Short E1 (pin 9) and E2 (pin 10) together as the PWM output.

TL494 resistors of output signals - Power management forum - TI E2E Oscillator: Connect CT (pin 5) to GND via 10nF