How does pwmcontroller ic tl494 works?

Answer 1

As mentioned earlier, it is a fixed frequency and variable duty cycle dual PWM control circuit. It does not require any external components to operate except a few resistors and capacitors for an oscillator. This oscillator is responsible for generating a sawtooth waveform according to timing capacitor CT. This TL494 IC generates signals by comparing a sawtooth waveform with two control signals of the error amplifiers. The output signal will be on during the time when sawtooth voltage is greater than the voltage at error amplifiers outputs. You can see a block diagram given above.

Output signal low: if sawtooth voltage less than the control signal voltage

Output signal High: if sawtooth voltage greater than the control signal voltage

Pulse-Steering Flip-Flop transfers the PWM output signal to output transistors.

Answer 2

This chip is designed to be part of a power supply circuit. When you want to create a higher or lower voltage, instead of wasting the extra energy with a linear regulator you can create a switching power supply. In this design the pulse width of a signal can be varied to change the output voltage. This switching waveform is then filtered to remove the high frequency (switching) component leaving behind the lower voltage and wasting less energy in the process. This concept can be also be used for motor drivers and amplifiers.

The Tl494 is designed as part of a closed loop control system, so it varies the pulse width depending on how close the output is to the desired voltage.