issue in voltage regulation using TL494

Thread Starter

silvi09

Joined Sep 26, 2021
11
I am using the given schematic for voltage regulation using TL494. When feedback is not given, that is point A and B are not connected, then I am getting a pulse of 35% duty cycle of 0-12V. But when the feedback is given ( A and B gets connected), then in the output I am getting a 12V DC rather than a pulse even though the positive and negative terminal of error amplifiers have some difference of voltage and there's a sudden large amount of current flow at point C and D that is the primary side of the transformer. I am not unable to understand why the pulse is getting vanished with 12V dc and sudden large increase in current( i. e from 0.5 A to 1.6 A) in the primary side of the transformer circuit . Is there any blunder in the schematic.circuit.jpeg
 

Thread Starter

silvi09

Joined Sep 26, 2021
11

Alec_t

Joined Sep 17, 2013
12,812
why I couldn't use pin 2 for taking voltage feedback am unable to understand .
From the TI datasheet :-
1653647677367.png
This shows feedback to pins 1 and 16 (the non-inverting inputs of the error amps. Pins 2 and 15 get a reference voltage. dreived from pin 14.
 

Ian0

Joined Aug 7, 2020
5,147
UC3842 is the ubiquitous choice!
What is the purpose of your power supply?
You have an isolating transformer, but the ground connections on the primary side and secondary side are connected together. Why have an isolating transformer?
 

Thread Starter

silvi09

Joined Sep 26, 2021
11
UC3842 is the ubiquitous choice!
What is the purpose of your power supply?
You have an isolating transformer, but the ground connections on the primary side and secondary side are connected together. Why have an isolating transformer?
I

I am trying to design a power supply in which output voltage will be controlled by the increase and decrease of duty cycle of input PWM pulse. If m giving voltage feedback in pin 1 . Then initially no voltage will be there at pin 1 and so no PWM pulse can be generated and m not getting any output voltage. If I give any particular voltage to DTC pin that is pin 4 . Then duty cycle will be constant , it won't vary.
 

Ian0

Joined Aug 7, 2020
5,147
I am trying to design a power supply in which output voltage will be controlled by the increase and decrease of duty cycle of input PWM pulse. If m giving voltage feedback in pin 1 . Then initially no voltage will be there at pin 1 and so no PWM pulse can be generated and m not getting any output voltage. If I give any particular voltage to DTC pin that is pin 4 . Then duty cycle will be constant , it won't vary.
What is the purpose of your power supply?
You have an isolating transformer, but the ground connections on the primary side and secondary side are connected together. Why have an isolating transformer?
 
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