TPS62088A: Min On-Time, etc.

Shinichi Yokota

Genius 9715 points

Part Number: TPS62088A
Other Parts Discussed in Thread: TPS62088,

Hello,

I have two questions about TPS62088A (forced PWM).

What's the minimum on-time of the TPS62088A?
The WEBENCH Power Designer tool shows a switching frequency result of about 4.2 MHz with TPS62088 (PFM/PWM) while the result is 2.17 MHz with TPS62088A (forced PWM) under the following condition. The TPS62088A's result is clearly strange from the data sheet specs, too. Is something wrong with the WEBENCH simulation?
- Conditions
  - Input voltage: 3.3 V
  - Output: 0.9 V/1.8 A

Best regards,
Shinichi Yokota

over 2 years ago

0 Febin over 2 years ago

TI__Mastermind 27990 points

Hi Yokota-san,

I will check Webench and update you later today.

Regards,

Febin

0 Febin over 2 years ago in reply to Febin

TI__Mastermind 27990 points

Hi Yokota-san,

I see your point. However, I need to cross-check with the Webench team if there is any difference between the two designs. This may take a couple of days to debug.

For now, I suggest to rely on the datasheet. The test conditions mentioned above is available in the d/s already.

I will keep you posted.

Regards,

Febin

0 Shinichi Yokota over 2 years ago in reply to Febin

TI__Genius 9715 points

Febin,

How about my first question? Is the minimum on-time of the TPS62088A available?

Best regards,
Shinichi Yokota

0 Febin over 2 years ago in reply to Shinichi Yokota

TI__Mastermind 27990 points

Hi Yokota-san,

Please calculate the Ton using the equation 1 in the datasheet for the application conditions.

Regards,

Febin

0 Shinichi Yokota over 2 years ago in reply to Febin

TI__Genius 9715 points

Febin,

If V_IN and V_OUT are both within the recommended operating ranges, I believe the TPS62088A won't go below the real minimum t_ON. I'd like to just confirm it. Is the real minimum t_ON value not available?

Best regards,
Shinichi Yokota

0 Febin over 2 years ago in reply to Shinichi Yokota

TI__Mastermind 27990 points

Hi Yokota-san,

If the Vin_min and the Ton time needed is calculated, then it should not be a problem. In DCS, the Ton is fixed and the fsw changes according to the duty cycle.

I will check internally if we have some data available and get back to you early next week.

Regards,

Febin

0 Febin over 2 years ago in reply to Febin

TI__Mastermind 27990 points

Hi Yokota-san,

I would like to clarify something,

Does the customer have any concerns on the switching frequency variation or you want to know the minimum on time value for particular frequency?

If they are interested in what minimum on time they can get for extreme duty cycles, then this is not available.

Regards,

Febin

0 Febin over 2 years ago in reply to Febin

TI__Mastermind 27990 points

Hi Yokota-san,

Any updates to share?

Regards,

Febin

0 Shinichi Yokota over 2 years ago in reply to Febin

TI__Genius 9715 points

Febin,

If the parameter value were available, I thought it could be used to verify whether the TPS62088A surely works properly under an operating condition. It's no more than that.

By the way, do you have any update on this WEBENCH issue?

Febin said:
I see your point. However, I need to cross-check with the Webench team if there is any difference between the two designs. This may take a couple of days to debug.

Best regards,
Shinichi Yokota

0 Febin over 2 years ago in reply to Shinichi Yokota

TI__Mastermind 27990 points

Hi Yokota-san,

If the concern of the customer is really that they do not go below min on time of the device then there is no risk here with this device.

Shinichi Yokota said:
By the way, do you have any update on this WEBENCH issue?

I am working closely with Webench team on this... It is not yet finalized... This will take a couple more days...

Regards,

Febin

0 Shinichi Yokota over 2 years ago in reply to Febin

TI__Genius 9715 points

Febin,

Febin said:
If the concern of the customer is really that they do not go below min on time of the device then there is no risk here with this device.

That's correct.

Febin said:
I am working closely with Webench team on this... It is not yet finalized... This will take a couple more days...

I'm looking forward to your feedback.

Best regards,
Shinichi Yokota

0 Febin over 2 years ago in reply to Shinichi Yokota

TI__Mastermind 27990 points

Hi Yokota-san,

I will update you. Thanks

0 Febin over 2 years ago in reply to Febin

TI__Mastermind 27990 points

Hi Yokota-san,

Webench issue is fixed. Please check by mid of the week.

Regards,

Febin

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TPS62088A: Min On-Time, etc.