TPS62902EVM-069: AEE feature

Yuta Nishie

Part Number: TPS62902EVM-069

Hi,

I have any questions.
It would be appreciated if you answer.

1. I read "7.4.2 AEE (Automatic Efficiency Enhancement)" on page 14 of the data sheet, but I couldn't understand AEE feature.
If you have explanatory material for AEE feature, please give me it.

2. Does the AEE feature affect the transient response characteristics?
As a background, I connected JP2 to Open (16.9kohm, 1MHz, Auto PFM / PWM) or GND (2.5MHz, Auto PFM / PWM with AEE) to operate EVM.
At this time, "Open" was more responsive than "GND".
I don't understand why "Open" is more responsive even though the switching frequency is slower.
Is it due to AEE feature?

Best Regards,

Nishie

over 2 years ago

0 Amod Vaze over 2 years ago

TI__Mastermind 23130 points

Hi Nishie,

The only explanation is what is available in the datasheet section 7.4.2. A related article is here: https://www.electronicdesign.com/power-management/article/21800690/aee-boosts-efficiency-for-loweroutputvoltage-stepdown-converters The frequency is lowered with lower Vout in order to keep the inductor ripple fairly constant.

For question 2, is it possible to share the Vin, Vout, Iout load step and slew rate (are these identical in both test cases)? Also are you using the same inductor or different inductor - what is the value used for each mode test? I would need to check the frequency of operation under these conditions. If you have any scope shots, feel free to share.

Thanks,

Amod

0 Yuta Nishie over 2 years ago in reply to Amod Vaze

Genius 3230 points

Hi Amod,

Thank you for your reply.

1. Thank you for the material information.

2. Please wait for a while as we will measure the waveform.

Best Regards,

Nishie

0 Yuta Nishie over 2 years ago in reply to Yuta Nishie

Genius 3230 points

Hi Amod,

The measurement was carried out.

I would appreciate it if you could check the PDF and comment.

waveform of TPS62902EVM.pdf

Best Regards,

Nishie

0 Amod Vaze over 2 years ago in reply to Yuta Nishie

TI__Mastermind 23130 points

Hi Nishie,

Thank you for the waveforms. I am checking to see if AEE can affect transient performance but for the 2.5MHz case, the recommended value for inductor is 1uH. You should see improvement in transient response using the 1uH inductor instead of the 2.2uH inductor. Will this inductor change work for your requirements?

Thanks,
Amod

0 Yuta Nishie over 2 years ago in reply to Amod Vaze

Genius 3230 points

Hi Amod,

Thank you for checking.
Please let me know if you find out whether AEE affects the transient performance.
I would like to check if there is a 1uH inductor in the company and make a measurement.

Best Regards,

Nishie

0 Amod Vaze over 2 years ago in reply to Yuta Nishie

TI__Mastermind 23130 points

Hi Nishie,

Yes I am checking with design team on this and will reply here as soon as I have an update hopefully in the next two days or earlier.

Thanks,

Amod

0 Yuta Nishie over 2 years ago in reply to Amod Vaze

Genius 3230 points

Hi Amod,

Thank you for your support.

Best Regards,

Nishie

0 Shuai Fan over 2 years ago in reply to Yuta Nishie

TI__Genius 13401 points

Hi Yuta!

Thanks for your feedback. Shall we close it ?

BSR-MV

Shuai

+1 Amod Vaze over 2 years ago in reply to Amod Vaze

TI__Mastermind 23130 points

Hi Nishie,

I confirmed that only change with AEE is the on-time generation to try and keep the inductor ripple constant as mentioned before. During transient response, the control scheme is identical between both the modes (1Mhz and 2.5MHz AEE). During undershoot, the control scheme increases the on-time trying to reach 100% duty cycle in order to recover from the undershoot. During overshoot, the switching is stopped in order to recover from the overshoot. You can read more about this in the transient response section here: https://www.ti.com/lit/an/slyt531/slyt531.pdf Please consider using the 1uH inductor when using the 2.5MHz AEE mode in order to improve the transient response.

Hope this helps.

Thanks,

Amod

0 Yuta Nishie over 2 years ago in reply to Amod Vaze

Genius 3230 points

Hi Amod,

Thank you for providing information.
Please close this thread.

Best Regards,

Nishie

0 Shuai Fan over 2 years ago in reply to Yuta Nishie

TI__Genius 13401 points

Hi Yuta!

Thank you!

BSR-MV

Shuai

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TPS62902EVM-069: AEE feature