BQ24600: Schematic Review - No battery charge, Flashing STAT LED

Kris Parrent

Part Number: BQ24600

Good afternoon,

We are successfully booting up and there is not any noticeable heat generation, but we are getting a flashing STAT light (fault condition) and the PGn signal is only active in a specific voltage range within a few volts of the battery.

This is a new battery pack, so I am waiting on confirmation from the vendor on the thermistor details, but the voltage on TS looks to be in rage (2.2 V). However, VREF is also 4.1-4.2 V instead of the expected 3.3 V.

Do you have any thoughts?

Thank you,

Kris

over 1 year ago

0 Michael Emanuel35 over 1 year ago

TI__Mastermind 35605 points

Hello,

I am having trouble viewing the schematic due to the upload method, but I can tell you that I think there is not the required VREF capacitor of 1 uF. This could explain the not normal VREF voltage. Please run through the Typical Application in the datasheet and make sure all the required components are present.

Regards,

Mike Emanuel

0 Kris Parrent over 1 year ago in reply to Michael Emanuel35

Intellectual 795 points

Hi Mike,

Thanks- after adding a 1uf cap to VREF I see a stable 3.3V operation and a solid LED on PG. STAT however is still flashing indicating an error.

Let me try to upload the schematic again. I am using a 4-cell Li-Ion which is currently at 14.0 V. The thermistor is measuring 1.6 V which looks to be in the appropriate range.18408.Schematic Prints.pdf

0 Michael Emanuel35 over 1 year ago in reply to Kris Parrent

TI__Mastermind 35605 points

Hello,

Another thing I noticed. The pullup resistors for the open drain pins are too small. The pins are rated for 5 mA and 3.3V/499 Ohms is 6.6 mA. This could potentially damage the device. Replace the resistors with say 10kOhm and replace the IC and please note the difference.

Regards,

Mike Emanuel

0 Kris Parrent over 1 year ago in reply to Michael Emanuel35

Intellectual 795 points

Hi Mike,

I will try that. For reference, the 499 Ohm resistors were used because of a TI reference design. Here is the link to the schematic https://www.ti.com/lit/pdf/tidrgx1

I will report back results later today.

Thanks for the help.

Kris

0 Kris Parrent over 1 year ago in reply to Kris Parrent

Intellectual 795 points

Hi Mike,

Replaced the IC and the resistors, and still have the same situation with the flashing STAT, but both LEDs are very dim now. The 10k resistor is probably too big, but I can continue working on that so long as they are just indicators and not effecting charging operations.