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BQ24620: BQ24620 Icharge query

Star Xu
Genius 9645 points
Part Number: BQ24620
Other Parts Discussed in Thread: BQ24610

Hi

The customer set the Icharge, the problem as below:

According to the current formula in the data sheet, the charging current is 800mA and the set voltage is 0.16V. However, the actual test reaches 800mA at 0.17V. This error is within 5%, this is within the error range.

If the sense resistor is 0.1ohm, the theoretical calculation setting the voltage of 1.6V can reach 800mA, but the actual need 1.6V can reach about 500mA.

Why is the error so big?

Waiting for your reply.

Thanks

Star

  • 0
    TI__Genius 13495 points

    Hello Star,

    Star Xu said:
    If the sense resistor is 0.1ohm, the theoretical calculation setting the voltage of 1.6V can reach 800mA, but the actual need 1.6V can reach about 500mA.

    I recommend checking the placement of the sense resistor. The charging-current sensing resistor should be placed right next to the inductor output. Route the sense leads connected across the sensing resistor back to the IC in same layer, close to each other (minimize loop area) and do not route the sense leads through a high-current path (see Figure 27 of the BQ24610 datasheet for Kelvin connection for best current accuracy). Place the decoupling capacitor on these traces next to the IC.

    I also recommed placing the output capacitor next to the sensing resistor output and ground. Output capacitor ground connections must be tied to the same copper that connects to the input capacitor ground before connecting to system ground.

    Here is a layout guideline for this device:BQ24620 Layout

    Best Regards,

    Christian.