BQ79731-Q1: Bq79731 DVDD Fault

korcan tuna

Part Number: BQ79731-Q1

Tool/software:

Dear Team,

We have designed our energy storage system based on the reference design using the bq79731 and bq79718 ICs. In our implementation, 15 bq79718 modules are connected in series and managed by a single bq79731 PDU.

Unfortunately, we have encountered a failure in the bq79731 IC. Upon analysis, we observed that when a wake-up signal is applied, DVDD rises only to 0.8 V, and the IC does not power up. Meanwhile, AVDD is measured at 2.5 V. Despite attempting communication via both the daisy-chain and UART/SPI interfaces, the IC remains unresponsive.

We measured the resistance between the DVDD pin and ground to further investigate the issue. SRP-SRN /ground(pins are measured seperately like SRP1-Ground, SRN1-Ground).The results are as follows:

Measurement Point	Faulty IC	Functional IC
DVDD – GND	51 Ω	180 kΩ
Sense Pins (SRP1-2 – SRN1-2)	51 Ω	220 kΩ

Note: As per the datasheet and reference design, DVDD is not connected to a load and is only connected through a decoupling capacitor.

We are currently unable to determine the root cause of the failure and would appreciate your support in identifying the potential reason(s) behind this issue.

Thank you in advance for your assistance.

2 months ago

0 Evan Han 2 months ago

TI__Prodigy 500 points

Hi,

You can troubleshoot the problem by taking the following steps:

1.It seems that the ground impedance of the chip is somewhat different from that of the normal chip. You can perform an ABA test on the faulty IC to see if the fault follows the IC

2.Ensure that the wake ping signal sent by the MCU complies with the data sheet

0 korcan tuna 2 months ago in reply to Evan Han

Intellectual 300 points

Hi Evan,

The system had been operating successfully in the product for three weeks before the IC became damaged. After the issue occurred, only the IC was replaced, and the system is now functioning properly again. All other components on the PCB appear to be in good condition; we verified them using a multimeter.

The only damaged parts were the IC’s DVDD pin and sense pins. The sense pins are connected to a 50 μΩ sense resistor, which is tied to the rack-, representing the negative terminal of a 15-module battery pack.

0 korcan tuna 2 months ago in reply to korcan tuna

Intellectual 300 points

Hi Team,

Is there any update or suugestion?

0 Evan Han 2 months ago in reply to korcan tuna

TI__Prodigy 500 points

Hi,

If the system resumes normal operation after replacing the IC, it means that the problem is caused by IC damage. The fault is with the IC. You can send this IC to the quality colleague for FA, and then we can know the root cause of the IC damage.

Thanks

0 korcan tuna 2 months ago in reply to Evan Han

Intellectual 300 points

Hi Evan,

How can I send the IC? Is there any DHL code or address?

+1 Evan Han 2 months ago in reply to korcan tuna

TI__Prodigy 500 points

Hi Korcan,

You can connect the Field Quality colleague in your region, they will provide the shipment address for you.

Thanks

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BQ79731-Q1: Bq79731 DVDD Fault