BQ25700A: Buck-Boost operation

tateo yamashiro

Part Number: BQ25700A
Other Parts Discussed in Thread: LM5175

Hi,

We got a question from customer about bq25700A.
Could you help us?

[Question]
Our customer would like to make sure Buck-Boost operation.

- Is there any application notes of Buck-Boost operation?
- What is the condition of moving to Buck-Boost region?
- We are thinking the operation of this IC is similar to LM5175. Are these IC same operation?

Best Regards,
tateo

over 8 years ago

0 Wang5577 over 8 years ago

TI__Guru 56650 points

When the input is in +10% to -10% of Vout, the charger could run into buck-boost mode. After in 10% region, only one pair switch will be active in one switching cycle which gives a high efficiency in buckboost. You can compare it with other part.
That one pair switch could be buck switches or boost switches which is decided by the feedback loop. I cannot discourse more.

0 tateo yamashiro over 8 years ago in reply to Wang5577

Guru 10890 points

Hi, Thank you for your reply. How does the IC monitor the output voltage and the input voltage? Does the IC use SRN and VBUS terminal?

Best Regards,
tateo

0 Wang5577 over 8 years ago in reply to tateo yamashiro

TI__Guru 56650 points

Input side only VBUS; output side either VSYS or SRN.

0 tateo yamashiro over 8 years ago in reply to Wang5577

Guru 10890 points

Hi, Thank you for your support. Sorry to bother you again. Could you inform me of the function of comp1 and comp2? Does the IC have the independent error AMP for regulation to boost mode and buck mode?

Best Regards,
tateo

0 Wang5577 over 8 years ago in reply to tateo yamashiro

TI__Guru 56650 points

COMP1 and COMP2 for loop compensation. Currently, we don't allow customer change the compensation loop parameter. BTW, buck and boost share a same AMP.

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BQ25700A: Buck-Boost operation