BQ76940: when Charging Q1 N-MOSFET increase temperature.

Dexter Choi

Expert 2795 points

Part Number: BQ76940
Other Parts Discussed in Thread: UCC27424

Dear Sir,

When charging BAT PACK. Q1 N-MOSFETs are increase Temperature and very hot.

When TURN OFF Q1 N-MOSFETs. GATE voltage is 4V.

When TURN ON Q1 N-MOSFETs. GATE voltage is 12V.

If BAT CHARGING Voltage and BAT PACK are same. When TURN OFF Q1 N-MOSFETs. GATE voltage is 0V.

BAT CHARGING Voltage : 84V

BAT PACK voltage : 70V

could you let me know advise me about this issue.,

please refer below wave form.

3250.LOW-SIDE FET_gate voltage abnormal.pptx

over 4 years ago

0 Matt Sunna over 4 years ago

TI__Guru* 77283 points

Hi Dexter,

Can you let me know which FET part number you are using and your typical charge and discharge currents? Are the FETs properly rated for the voltage applied and is the RDSon reasonably low?

Best regards,

Matt

0 HYOUNG RAE RYU over 4 years ago in reply to Matt Sunna

Prodigy 40 points

Hi Matt.

I'm SONGUO H/W engineer.

I attach test data.200403_SONGUO_FET-1.pptx

We are using the FET below.(IPB048N15N5LF)

Charge/Discharge is up to 20A~100A.(20s/72V) and the FET is controlled by UCC27424.

[Additional question]

1) Is it safe to use a resistance value of R301(1M --> 150kohm)?

2) What are the benefits of using a p-ch FET for UCC27424?

Please check the attachment.

0 Matt Sunna over 4 years ago in reply to HYOUNG RAE RYU

TI__Guru* 77283 points

Hi Dexter,

I am not an expert on the UCC27424, so I am reassigning your question to the expert for this device.

Best regards,

Matt

0 Mamadou Diallo over 4 years ago in reply to Matt Sunna

TI__Genius 13445 points

Hi Dexter,

I have sent you an email, let's continue to debug there while I mark this thread as resolved.

Regards,

-Mamadou

0 Dexter Choi over 4 years ago in reply to Mamadou Diallo

Expert 2795 points

Hi Mamadou,

I got the your email.

Thank you for your support!!

Power management

Power management forum

BQ76940: when Charging Q1 N-MOSFET increase temperature.