BQ24780EVM: About HPB operation time

Kenji Ohno1

Part Number: BQ24780EVM

Hi Team,

I have received questions from customers about the attached waveform.

For normal load fluctuation, the reaction time is as fast as 200 μs, but HPB reaction time will be as long as 53 ms at the time of switching from battery operation to 19 V operation. Is it possible to make 53 ms faster?

I will wait for suggestions from you if there is a solution.

Best Regards,

Kenji

BQ24780　Hybrid Power Boost.pptx

over 5 years ago

0 Jeff F over 5 years ago

TI__Guru*** 143960 points

Kenji,

I am confused by the question. Hybrid boost mode turns on once the input current sensed over Rac exceeds the input current limit setting. In the second plot, 19VIN is applied but that voltage, and therefore no input current, is passed to SYS. Why are the input AC FETs off initially?

0 Paul Yeh over 5 years ago in reply to Jeff F

TI__Genius 13625 points

Kenji,

Could you also measure some waveform for our reference? I also captured one turbo-boost response waveform during load transient testing for your reference at first. And the response time is around 40us based on our testing condition.

Thanks

0 Jeff F over 5 years ago in reply to Paul Yeh

TI__Guru*** 143960 points

Is there an update on this? If not, I would like to close this post.

0 Kenji Ohno1 over 5 years ago in reply to Jeff F

Genius 5095 points

Hi Jeff,

Sorry late response.

Please wait a little more.

Kenji

0 Jeff F over 5 years ago in reply to Kenji Ohno1

TI__Guru*** 143960 points

Haven't heard from you in a while so I will be closing this ticket.

0 Kenji Ohno1 over 5 years ago in reply to Jeff F

Genius 5095 points

Hi Jeff,

Sorry to be late replying.

I got additional information.

① HPB operation when the load increases during input of Power Supply # 1 (19 V) → B_STAT: 82 μs.

② HPB operation by 19 V input from battery operation, high load current (19 V / 4 A in attached file) → B_STAT: 53 μs.

BQ24780　Hybrid Power Boost(2).pdf

Request; I want to know how to set B_STAT of ② to about 100 μs.

Best Regards

Kenji

0 Jeff F over 5 years ago in reply to Kenji Ohno1

TI__Guru*** 143960 points

Kenji,

The delays getting into hybrid boost mode that you documented are typical. If the buck converter is operating in CCM, meaning the inductor is already charged, then the delay to enter hybrid boost mode is in the 50-100us range. If the buck converter is operating in DCM, meaning the inductor is not charged, the delay entering boost mode from a low current to high current transient can be in the 50ms range. This a combination of the buck converter internal delays and the inductor slew rate.

0 Kenji Ohno1 over 5 years ago in reply to Jeff F

Genius 5095 points

Hi Jeff,

Thank you for answering.
Does that mean that your view can not be about 100 us?
Is there a way to shorten it to about 100 μs?

Best Regards,
Kenji

Power management

Power management forum

BQ24780EVM: About HPB operation time