BQ40Z80: SMBus Pulldown Resistance

Antonio Fadhel

Part Number: BQ40Z80

Hi,

My customer is measuring 400kOhm pulldown resistance on the SMBus clock and data lines of the bq40z80, but the datasheet drawing and specs show 1Mohm. They have removed everything else from the lines and even measured on an IC off the reel. Can you please confirm if this is expected?

I am wondering if it could be due to the leakage current of the internal Zener diodes and/or SMBxEN switches.

Thanks,

Antonio

over 5 years ago

0 Andy Liu (BMS) over 5 years ago

TI__Guru 52115 points

Hi Antonio,

I will check some bq40z80 devices and get back to you.

Andy

0 Antonio Fadhel over 5 years ago in reply to Andy Liu (BMS)

TI__Genius 9410 points

Hi Andy,

Have you had a chance to measure the devices? When can we expect feedback?

Thanks,

Antonio

0 Antonio Fadhel over 5 years ago in reply to Antonio Fadhel

TI__Genius 9410 points

Hi Andy,

The customer needs this information. When can we expect feedback?

Thanks,

Antonio

0 Kang Kang over 5 years ago in reply to Antonio Fadhel

TI__Mastermind 24870 points

Hello Antonio,

Let me follow up with Andy on this.

0 Andy Liu (BMS) over 5 years ago in reply to Antonio Fadhel

TI__Guru 52115 points

Hi Antonio,

As far as I know, it is not possible to measure the pulldown resistance with a loose part.

How did the customer take the measurement?

To my best knowledge, the correct measurement is to power the device on and pull the SMBD or SMBC pin to some voltage (e.g. 3.3V) and then measure the leakage current flowing into SMBD or SMBC. The pulldown resistance should be the voltage divided by the leakage current.

Andy

Power management

Power management forum

BQ40Z80: SMBus Pulldown Resistance