How to use TL494 pulse width modulation control IC

How to use TL494 pulse width modulation control IC? Hi everyone I hope you are fine and doing well. Today tutorial is a introduction TL494 pulse width modulation control circuit. How we can use  TL494 pulse width modulation control IC to generate fixed and variable PWM.  I have already posted a tutorial on sg3525 pulse width modulation controller. You may also like to check it.  TL494 is PWM control or generation integrated circuit. TL494 is used in many applications. I have designed a proteus simulation on how to generate PWM signals and how to design a buck converter. It can be used in dc to dc converter circuits. It is also used in pure sine wave inverter circuits. I have made many power electronics based projects. You may also like to check them:

Introduction to TL494 PWM control IC

It is a complete PWM control IC. It can be used in single end operation as well as in push pull configuration. It also provides variable dead time which provides maximum range of PWM. It has all the functions required to design a power supply circuit. Block diagram of TL494 is shown below:

functional block diagram of TL494

It is a fixed frequency and a variable PWM IC. Pulse width is varied by comparing the saw tooth wave forms of two internal oscillators on the timing capacitor to anyone of the control signals. The output becomes high when control signal becomes lower than the voltage of sawtooth waveform. I recommend you to check data sheet of TL494 PWM control IC for more information and working details.

Pinout of TL494 PWM CONTROL circuit

Pinout and pins details of TL494 is given below: pinout of TL494

Circuit diagram to generate PWM signals with TL494

Below circuit diagram can be used to generate 2 PWM signals. Width of each PWM can be controlled through these variable resistors. PWM generation using TL494

Simulation results of two PWM are shown below:

PWM generation using TL494 simulation results

Buck converter design using TL494 pulse width modulation control circuit

I have designed a buck converter using TL494 as an example. Input to buck conveter is 25 volt and output is in the range of  7  to 19 volts. User can change the output voltage with the help of variable resistor shown in circuit diagram below. TIP127 is used a switching device. buck converter circuit diagram using TL494

For detailed working of buck converter check the video simulation. In this video I have explained the working of buck converter design using this pulse width modulation controller circuit.  I have used variable resistor to control duty cycle of pulse width. Another variable resistor is used to control current.  Input voltage is 25 volt and output voltage is in the range of 5 volt to 19 volt. When duty cycle is maximum output voltage will be 19 volt and when duty cycle is minimum, output voltage will be 5 volt. Voltage divider circuit is used for feedback voltage measurement and shunt resistor is used for feedback current measurement.

One Response

  1. Suresh March 27, 2018

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