TPS22924C: NMOS forward voltage

Ann_Lien

Part Number: TPS22924C
Other Parts Discussed in Thread: TPS22924

Hello expert,

My customer is facing TPS22924 failure and checked with its Cin and CL. CL is larger than Cin in their original schematic. they faced the issue that 1.8V power rail will see 1.12V output voltage on it. May we know if you can explain this issue? And customer would like to know the forward voltage for the NMOS body diode. Thanks a lot!

Best regards,

Ann Lien

over 2 years ago

0 Patrick Shalton over 2 years ago

TI__Mastermind 35010 points

Hi Ann,

When the customer is seeing 1.12V on the 1.8V rail, is the 1.8V rail powered or floating?

I will check on the NMOS forward voltage and let you know when I have an answer.

Thanks,

Patrick

0 Ann_Lien over 2 years ago in reply to Patrick Shalton

TI__Genius 15700 points

Hello Patrick,

1.8V is powered, there is no fault on input side. Thanks!

Best regards,

Ann Lien

0 Patrick Shalton over 2 years ago in reply to Ann_Lien

TI__Mastermind 35010 points

Hi Ann,

Thanks for the information, I will inquire to the team about the body diode forward voltage and let you know the value.

Thanks,

Patrick

0 Ann_Lien over 2 years ago in reply to Patrick Shalton

TI__Genius 15700 points

Customer is having significant fail rate on this case so please help. Or if there is any input which is not related to forward voltage, please let me know. Thanks!

0 Patrick Shalton over 2 years ago in reply to Ann_Lien

TI__Mastermind 35010 points

Hi Ann,

Absolutely, I am still in communications about the forward voltage.

In the meantime, can you provide the Cin/CL values in the customer's circuit? And, at what point in manufacture/field deployment is this part failing? With WCSP ICs like this, we are always cautious of the manufacturing quality, as we've seen a substantial number of final test/day 0 failures caused by non-careful manufacturing.

Thanks,

Patrick

0 Ann_Lien over 2 years ago in reply to Patrick Shalton

TI__Genius 15700 points

Hello Patrick,

They did use incorrect Cin/CL value but this issue can be observed when they use correct ratio for Cin/CL. For the manufacturing problem, they are under checking now. Thanks!

Best regards,

Ann Lien

0 Patrick Shalton over 2 years ago in reply to Ann_Lien

TI__Mastermind 35010 points

Hi Ann,

The body diode forward voltage is about 0.7V at 25C and 0.3V at 125C, so if VOUT exceeds VIN by more than that for longer than ~1us, the device can be damaged by high current across the FET. Please let me know if there are any comments about the manufacturing process.

Thanks,

Patrick

Power management

Power management forum

TPS22924C: NMOS forward voltage