TPS65381-Q1: Clamp protection characteristic of VBATP-pin and VBAT_SAFING-pin

masahiko shimizu

Part Number: TPS65381-Q1
Other Parts Discussed in Thread: TPS65381A-Q1

Hi,

My customer has a question of clamp protection characteristic of VBATP-pin and VBAT_SAFING-pin.

For protection of reverse battery connection, customer uses a diode in a battery line in series.
But when reverse battery connection, leakage current of this diode is 100 uA.

Do VBATP-pin and VBAT_SAFING-pin have damage by the negative voltage at this time?

Best regards,
Shimizu

over 8 years ago

0 Raymundo Hernandez-Toscano over 8 years ago

TI__Intellectual 810 points

Hi Masahiko Shimizu,

Has your customer considered using a P/N MOS FET with low RdsON in their reverse-protection scheme?

-Raymundo Hernandez

0 masahiko shimizu over 8 years ago in reply to Raymundo Hernandez-Toscano

Guru 11235 points

Hi Raymundo,

Thank you for your reply.
No, they has not considered using P/N MOS FET with low RdsON in their reverse-protection scheme.
Of course, I recommend using it.
But they has used only diode at currently design.
At this customer's situation, customer wants to know whether device has damage or not.

Best regards,
Shimizu

0 Scott Monroe over 8 years ago in reply to masahiko shimizu

TI__Mastermind 20590 points

Hi Shimizu-san,

The small leakage current of the diode reverse protection should not be an issue. The other option is to use the charge pump with an NMOS which does offer lower RDS, which if needed allows a lower input voltage on the battery since the drop will be less on a FET than a diode. However if this is not a concern standard reverse blocking with a diode is fine.

Best Regards,
Scott

0 masahiko shimizu over 8 years ago in reply to Scott Monroe

Guru 11235 points

Hi Scott-san,

I add a question about this.

Customer uses the diode to reverse protection at VBAT-pin.

At then, customer recently knew that the leakage current is about 1mA.

Is it problem?

And, Until how much leak current value does TPS65381A-Q1 accept?

Best regards,

Shimizu

0 masahiko shimizu over 8 years ago in reply to masahiko shimizu

Guru 11235 points

Hi Scott-san,

How is the progress about this?

Best regards,

Shimizu

0 Scott Monroe over 8 years ago in reply to masahiko shimizu

TI__Mastermind 20590 points

Hi Shimizu-san,

We do not have a specification of the allowed reverse current for the TPS65381A-Q1. TI is not aware of a specific issue that 1 mA would cause, but it recommended if possible to choose a different diode with a lower leakage specification or to thoroughly validate this diode in the application design. We have seen a range of diodes with reverse leakage as low as 4uA up to the 1mA range.

Best Regards,
Scott

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TPS65381-Q1: Clamp protection characteristic of VBATP-pin and VBAT_SAFING-pin