TL494: Max duty cycle?

Jerry Hsueh

Expert 2730 points

Part Number: TL494

Can the maximum duty cycle be greater than 0.5 when pin13 is grounded(Selects single-ended operation)?

I want to use TL494 to design buck circuit.

Thank you

Jerry

over 7 years ago

0 John Griffin1 over 7 years ago

TI__Mastermind 34465 points

Hello Jerry,
The TL494 has 2 separate PWM outputs
When OUTPUT CTRL (pin 13) pin is tied to ground the max duty cycle is 50% and the PWM outputs are in phase.
When this pin is tied to VREF the PWM outs are 180 degrees out of phase .
So for your buck regulator you can use either configuration if you require D<50% but you need to tie OUTPUT CTRL to VREF is you need D>50%
Regards
John

0 Jerry Hsueh over 7 years ago in reply to John Griffin1

Expert 2730 points

Hi John,

Help confirm that the buck circuit diagram below is correct, through the MCU to give PWM signal to adjust pin 1.

Whether the duty cycle can be adjusted to more than 50%? What's the maximum?

Thank you

Jerry

0 John Griffin1 over 7 years ago in reply to Jerry Hsueh

TI__Mastermind 34465 points

Hi Jerry,
Yes you will be able to use this configuration to drive the buck switch QS5.
You will be able to get a max duty cycle of 50% on QS5 provided the gate drive transformer is designed for this switching frequency.
Regards
John

0 John Griffin1 over 7 years ago in reply to John Griffin1

TI__Mastermind 34465 points

Hi Jerry,
I am marking this post as closed since it looks like all the requested information was provided.
Regards
John

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TL494: Max duty cycle?