BQ24296: Charger IC /Inductor gets heated up - Please review my schematic

Anil Sudhakaran

Part Number: BQ24296

Hi,

Have working BMS prototype board using BQ24296 Battery Charger, BQ27542 Fuel Gauge, BQ29701 protection IC. Functionally all the ICs are working fine.

Charger IC/Inductor is getting heated up when current limit is increased to default max ( Ilimit R = 120 ohm), with charging current at its default value of 2A. On a few boards charging IC failed.

Part of the schematic is below. Please review and suggest what could be wrong. Inductor used is IHLP2020BZER2R2M01 / Vishay make

Also, please review the ground path. All ICs ground are connected to B- now. Is it OK ?

Would like to send entire schematic for review in a private message.

Thanks in advance for help.

Regards,

Anil

over 6 years ago

0 Ning T over 6 years ago

TI__Guru 57781 points

Anil,

1. For the schematic, BOOT-SW cap should be 47nF, REGN cap should be 4.7uF, etc. Please double-check your schematic per Typical Application on the d/s or the BQ2429X EVM User's guide.

2. For the layout, please refer to https://e2e.ti.com/support/power-management/f/196/t/790169. Both devices are pin-compatible.

3. For heating concern, please refer to https://e2e.ti.com/support/power-management/f/196/t/787988.

Thanks,

Ning.

0 Anil Sudhakaran over 6 years ago in reply to Ning T

Expert 1125 points

Thanks Ning.

BOOT-SW cap , used 2 numbers of 100nF in series to get 50nF. This was done to standardize the components ( 100nF was already used ). Similarly for REGN, instead of 4.7uF in eval board, used an already used part (same schematic) 10uF. Can these cause issues ?

Anyway, have ordered 47nF. Will replace BOOT-SW cap to 47nF to test.

Working on your other comments too. Will update in 3-4 days.

Thanks & Regards,

Anil

0 Ning T over 6 years ago in reply to Anil Sudhakaran

TI__Guru 57781 points

Anil,

We haven’t heard back from you for a while, the thread is considered solved and closed.

Thanks,

Ning.

0 Anil Sudhakaran over 6 years ago in reply to Ning T

Expert 1125 points

Hi Ning,

I used a 1uH inductor and heating is reduced and it is OK now.

As per TI eval board schematic, Inductor value is 2.2uH. But in BOM section of eval board document it is mentioned as 1uH is assembled. (qty = 1).

Can you please confirm whether 2uH as mentioned in schematic is fine ? Or is 1uH the value to be used ?

Thanks & Regards,

Anil

0 Anil Sudhakaran over 6 years ago in reply to Anil Sudhakaran

Expert 1125 points

Hi Ning,

With Further test, it is found that high input cap that I had used on VBUS pin to standardize with another cap on board was the culprit.

Changed to 1uF as in Eval Board. Board/IC is OK now.

Thanks Ning for your help

Marking this as "resolved"

Regards,

Anil

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BQ24296: Charger IC /Inductor gets heated up - Please review my schematic