BQ25120A: Leakage currents

Marc Hoffknecht

Part Number: BQ25120A

So the bq25120A can be operated through the use of only I2C and /CD.

There are a number of open drain signals ( /PG, INT. /RESET ), and LSCTRL with a very weak internal pull down. From a layout perspective (more and continuous GND), EMI, and especially from the perspective of potential leakage currents, is it advisable to GND these signals or is it better to leave them unconnected ? What about the TS signal if no NTC is being used ?

Thank you.

over 5 years ago

0 Raheem over 5 years ago

TI__Mastermind 21590 points

Since LSCTRL has an internal pulldown, you can leave them floating. same with the open drain pins.

For NTC, you can either disable TS through I2C or set VTS to be between 50% and 60% of VIN with the voltage divider.

0 Marc Hoffknecht over 5 years ago in reply to Raheem

Prodigy 30 points

Functionally that makes sense. I was looking for the lowest possible leakage current setup (eg an external voltage divider on LSCTRL is not good). This may need knowledge about the internals of the chip.

0 Raheem over 5 years ago in reply to Marc Hoffknecht

TI__Mastermind 21590 points

Hello Marc,

Another way to do this is through I2C by disabling the TS function in reg 0x02 bit 7.

0 Raheem over 5 years ago in reply to Raheem

TI__Mastermind 21590 points

Hello,

Any updates here?

0 Marc Hoffknecht over 5 years ago in reply to Raheem

Prodigy 30 points

Raheem,

I was really looking for optimizing the (sub-uA) leakage currents. Just as a reference, the SDA/SCL pins specify up to 1 uA leakage. That's quite a lot in some applications and I am trying to avoid those where possible.

I believe I am fairly in tune with the functional setup of the chip, and I am aware that the TS can be disabled via I2C (done). My question is, which potential would I now connect it to in order to achieve the lowest possible leakage currents. GND ? Floating ?

And then the same for the other pins I mentioned. Is any particular connection better than others with respect to those sub-uA leakage currents ?

Thanks.

0 Raheem over 5 years ago in reply to Marc Hoffknecht

TI__Mastermind 21590 points

Hello Marc,

To reduce the Iq, i'll suggest leaving them floating.

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BQ25120A: Leakage currents