TPS610981: VMAIN biased without no VIN

K.Hamamoto

Guru 12155 points

Part Number: TPS610981

The customer would like to reduce the components around TPS610981.

And we have two question.

1)Our customer are considering such as a following configuration.

Can we remove the diode at the output(VMAIN) line?

We are considering the case of no BAT or no-battery voltage.

If VIN is 0V, VMAIN is 5V and may cause by the reverse current flow from VMAIN to VSW via the body diode of FET.

Is my understanding correct? If it so,we can not remove the diode.

2)The customer would like to consider to reducing the current consumption of system around TPS610981.

What is the components can we reduce the current consumption? L or Rin will be impact to the current consumption?

Best Regards,

Koji Hamamoto

over 5 years ago

0 Jasper Li over 5 years ago

TI__Mastermind 46905 points

Hi Koji,

the maximum voltage rating of the VMAIN is only 4.7V, so this pin can't be bias to 5V.
what is the battery voltage?

0 K.Hamamoto over 5 years ago in reply to Jasper Li

Guru 12155 points

Hi Jasper,

Thank you . Yes, you are right. I had missed the information.

How about (2) question? What is the components imapcted the power consumption?

Best Regards,
Koji Hamamoto

0 Jasper Li over 5 years ago in reply to K.Hamamoto

TI__Mastermind 46905 points

Hi Koji,

the R in the VIN pin and L don't impact the power consumption at this condition.

0 K.Hamamoto over 5 years ago in reply to Jasper Li

Guru 12155 points

Hi Jasper,

Thank you .

Regarding to (1) question, we are concerned about the reverse current though the body diode of internal FET if VMAIN is <4.7V and VIN and VSW is 0V. (They clamp the voltage at VMAIN pin to below 4.7V.)

Is that correct? If it so,how much can the current be flowed?

Best Regards,
Koji Hamamoto

0 Jasper Li over 5 years ago in reply to K.Hamamoto

TI__Mastermind 46905 points

Hi Koji,

the current through the high side FET should be very small. as this device doesn't have UVLO, it will try to switch if there is voltage in the output.
so the voltage in the VIN is very small even there is leakage current from VOUT to VIN. there will be current into the VMAIN pin, but it is not into the VIN. the current is consumed by the internal control circuit.

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TPS610981: VMAIN biased without no VIN