PWM signal generating circuit based on LM393

In summary, the conversation is about a PWM signal generating circuit based on LM393. The circuit consumes only 10 milliwatts of power at 5V and can work at 3.3V, 12V, and 18V. However, it cannot be used in switching power supplies due to the lack of a dead time feature. The person is seeking advice on how to modify the circuit for use in a switching power supply and has been recommended to look into gate drivers and output stages. They are also asked for more information on the desired SMPS topology and transistor drive circuits. The LM393 circuit is not ideal for use in an SMPS and there are many other dedicated ICs available for this purpose. One suggestion is
  • #1
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TL;DR Summary
This is a PWM signal generating circuit based on LM393 but cannot be used in switching power supplies. How can I do?
This is a PWM signal generating circuit based on LM393.
LM393 PWM Circuit.jpg


When I was running this LM393 circuit, I found that this circuit only consumes about 10 milliwatts of power at a voltage of 5V. Not only that, this circuit can work normally at 3.3V, 12V and 18V.
But later I found that this circuit cannot be used in switching power supplies.

It is missing something: dead time.So I would like to ask you how to make some changes to this circuit?
 
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  • #2
A switching supply may only need uni-polar drive, so dead time may not be needed.
I think you must also show the gate driver and the output stage you will use.
Many gate drivers include a dead time circuit.
What type of switching supply are you considering, buck or boost ?
 
  • #3
I'm not sure what you mean by dead time in a single PWM waveform. That concept is normally applied to a two phase PWM signal. So perhaps you could elaborate on your circuit requirements? What SMPS topology? What transistor drive circuits?

This circuit could be used in some SMPS, as @Baluncore said. But, no one designing a SMPS would use it. There are about million ICs dedicated to controlling power supplies which are simpler, work better, and usually will provide other necessary functions. You can start by looking at the TI website, they provide lots of parts and information about this stuff. Analog Devices is another good place to look.

One ancient IC that does provide two phase PWM with dead time (plus other stuff) is the SG3525A, have a look at that one.
 

FAQ: PWM signal generating circuit based on LM393

What is a PWM signal generating circuit based on LM393?

A PWM (Pulse Width Modulation) signal generating circuit based on LM393 is a type of electronic circuit that uses the LM393 integrated circuit to generate a PWM signal. This signal is a type of digital signal that is commonly used in electronic devices to control the speed of motors, dim lights, and regulate power output.

How does a PWM signal generating circuit based on LM393 work?

The LM393 integrated circuit is a comparator that compares two input signals and produces an output based on the difference between them. In a PWM circuit, the LM393 is used to compare a reference voltage with a sawtooth wave signal. The output of the comparator is then fed into a transistor circuit, which converts it into a PWM signal.

What are the advantages of using a PWM signal generating circuit based on LM393?

One of the main advantages of using this type of circuit is its ability to control the duty cycle of the PWM signal. This means that the circuit can adjust the amount of time the signal is on versus off, allowing for precise control of the output. Additionally, the LM393 is a low-cost and widely available integrated circuit, making it a popular choice for PWM circuits.

What are some common applications of a PWM signal generating circuit based on LM393?

PWM circuits based on LM393 are commonly used in motor control applications, such as in robotics or electronic speed controllers for drones. They are also used in lighting systems to dim LEDs or regulate the brightness of displays. Additionally, PWM signals are used in power supply circuits to regulate the output voltage.

Are there any limitations to using a PWM signal generating circuit based on LM393?

One limitation of this type of circuit is that it requires a stable reference voltage to function properly. Any fluctuations in the reference voltage can affect the accuracy of the PWM signal. Additionally, the duty cycle of the PWM signal may be limited by the frequency of the sawtooth wave signal, which is typically generated by an external timer circuit.

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