This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25756E: BQ25756E Schematic review

Part Number: BQ25756E
Other Parts Discussed in Thread: BQ25756

Tool/software:

Hi ti Team,

According to the customer's feedback, the abnormal situation of stopping charging after a period of time was caused by large fluctuations in output current sampling. Currently, there are changes to the following circuit, please help to systematically check whether it is OK and give suggestions, thank you.

As shown below, R71 and R7 are normal after changing from 10Ω to 100Ω. Is there any other problem after the two resistors are enlarged? In addition, only step-down charging function is used at present, can the circuit be optimized and simplified?

Application scenario: Adapter input voltage 29.4V, charging cut-off voltage 25.2V, charging current 2.5A.

Now we need help to review whether there is any problem with the schematic design.

  • Hello Ken,

    Thanks for working with this. Here are a few quick recommendations for the current surge problem:

    R71 and R72 should be 10Ω.

    Can you move C50 and C51 to the other side of the battery sense resistor? C51 should be as close to QT11 as possible.

    Can you move C53 to the other side of the input sense resistor? C53 should be as close to QT12 as possible.

    Also, the VAC pin needs to have 1µF capacitor close to it.

    Also, can you do a first pass review with the BQ25756 schematic checklist also? I'll look over the schematic again afterwards. Here's the checklist: e2e.ti.com/.../faq-bq25756-schematic-and-layout-checklist

    Best Regards,
    Ethan Galloway