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BQ25570: BQ25570 VBAT pin greater than 4.2V

Part Number: BQ25570
Other Parts Discussed in Thread: TIDA-00588

We're using BQ25570 in our product. Currently we are having problems with this IC. Devices are sent back by customers to claim a lot of warranty. I checked the VBAT pin of IC BQ25570 is higher than 4.2V (4.5 - 4.8V). Common value is about 4.18V. This IC is are charging for 18650 cells, so the 18650 cells broken and the device stopped working. I want to find out what could be the cause of VBAT pin higher than 4.2V. I refer to the design according to TIDA-00588

  • Hi Chung,

    The only two known but preventable issues that cause this IC to fall out of regulation are:

    1. Noise injected into VSTOR if the 0.1uF bypass capacitor (CBYP) is not placed as close as possible between the VSTOR pin and nearest GND (VSS) pin as shown in the datasheet recommended layout on datasheet page 35.

    2. Parasitic resistors formed across the megaohm resistors from solder flux if the board isn't cleaned properly after assembly as explained in datasheet section 10 starting on page 34.