TL494: "Dead-Time Control" of the TL494.

KIM Andy

Expert 2530 points

Part Number: TL494

The question about the "Dead-Time Control" of the TL494.

In the TL494 Application Report

- "The dead-time control provides 5% to 100% dead time"

I would like to know how to apply the above specification from 0% to 100% dead time.

That's about it.Thank you very much.

over 8 years ago

0 Peter Meaney over 8 years ago

TI__Mastermind 31580 points

Hi Andy,

Looking at the datasheet the minimum deadtime is 5%, "The dead-time control comparator has a fixed offset that provides approximately 5% dead time"

Can you tell me more about your application and it requires 0% dead-time.

Regards

Peter

0 KIM Andy over 8 years ago in reply to Peter Meaney

Expert 2530 points

Hi Peter,
I have now input 0V to Pin 4 using the DAC.
I want to create a duty to 0%. There is now a 5% duty cycle.

Can I set the duty cycle to zero when I input 0V into the DAC?
If not, can I set the duty cycle to 100% when I input 0V into the DAC?

If TL494 is not available, will there be any replaceable items?

Please confirm.

Thank you.

0 Oliver Pan91 over 8 years ago in reply to KIM Andy

TI__Intellectual 2230 points

Hi Kim,

You can set 0% duty cycle to the internal BJTs Q1&Q2 if you pull DTC pin above 2.6V. If you want to control the duty cycle by external signal, I recommand to pull the DTC to 0V and use the FEEDBACK pin to set the duty cycle by apply a DC voltage from 0V to 3.7V. The internal error amplifiers should be bypassed, refer to the test circuit in page 8 of the datasheet.

Thanks
Oliver

0 KIM Andy over 8 years ago in reply to Oliver Pan91

Expert 2530 points

Thank you.
It has helped a lot.

0 KIM Andy over 8 years ago in reply to Oliver Pan91

Expert 2530 points

Hi, Oliver

Circuit configuration is as follows.

There is currently only a 100% duty cycle.
The duty cycle is not changed.
FEED_BACK = DAC input = 0 ~ 2.63V (variable)
DTC = 3.8Vdc
Pin1,16 short,
Pin2,15,14,13 short - Vref

What would need to be modified?

0 Oliver Pan91 over 8 years ago in reply to KIM Andy

TI__Intellectual 2230 points

Hi Kim,

I am sorry that I mix up the pin3 and pin4 in my last reply(have been corrected), and the duty cycle which I refer to is for the internal BJTs, which are inverse to the final outputs C1/C2.

Thanks
Oliver

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TL494: "Dead-Time Control" of the TL494.