BQ25798: Substitute

Vaibhav Khatri

Prodigy 140 points

Part Number: BQ25798
Other Parts Discussed in Thread: BQ25792, BQ25730

Tool/software:

Hello,

I am designing a UPS around BQ25798 but it is out of stock, is there any similar IC offered by TI?

Thanks and regards

Vaibhav

7 months ago

0 Christian Moyer 7 months ago

TI__Mastermind 31366 points

Hello Vaibhav.

Will your design require a removal battery?

We have the BQ25792 which is very similar to the BQ25798, however the BQ25792 was designed for embedded applications like smartphone. At battery removal, 792 BAT then SYS pins hit OVP and then turn off converter for 30ms. Any load on SYS crashes SYS.

Best Regards,

Christian.

0 Vaibhav Khatri 7 months ago in reply to Christian Moyer

Prodigy 140 points

I looked at BQ25792 as well before selecting BQ25798, the only missing feature is Fast-backup mode and I need that feature in my design, other alternative I looked was bq25730 which have MOSFET driving options so I have to use external MOSFETs with that which complicates my design, it also does not have Fast-backup mode.

It would be good if you can clarify that BQ25792 can provide the fast-backup mode functionality as well.

Thanks

Vaibhav

0 Christian Moyer 7 months ago in reply to Vaibhav Khatri

TI__Mastermind 31366 points

Hello Vaibhav,

I checked yesterday and BQ25798 was out of stock, but today it is back in stock.

Can you check if you are able to order them?

Best Regards,

Christian.

0 Vaibhav Khatri 7 months ago in reply to Christian Moyer

Prodigy 140 points

Yes, they are in stock but I wish to order from a different source.

One more doubt, BQ25792 is also pretty much similar to BQ25798 the only difference being the back-up power mode. But can I use OTG capabilities of bq25792 to do fast switching when input source is disconnected?
So it can mimic the functionality of bq25798.

Thanks

Vaibhav

0 Christian Moyer 6 months ago in reply to Vaibhav Khatri

TI__Mastermind 31366 points

Hello Vaibhav,

Vaibhav Khatri said:
One more doubt, BQ25792 is also pretty much similar to BQ25798 the only difference being the back-up power mode. But can I use OTG capabilities of bq25792 to do fast switching when input source is disconnected?
So it can mimic the functionality of bq25798.

Backup mode and OTG mode are different. Backup mode is simply OTG mode that turns on automatically when input power droops and provides the OTG output back to PMID pin not VBUS pin. So it will be dependent on where your load is.

Best Regards,

Christian.

0 Vaibhav Khatri 6 months ago in reply to Christian Moyer

Prodigy 140 points

Okay, so BQ25798 have a path leading to PMID, but is it same in BQ25792?

Cause BQ25798 can provide power on PMID in cases of VBUS absence but can BQ25792 can also do the same?

0 Christian Moyer 6 months ago in reply to Vaibhav Khatri

TI__Mastermind 31366 points

Hello Vaibhav,

I will provide feedback by EOD Wednesday.

Best Regards,

Christian

0 Vaibhav Khatri 6 months ago in reply to Christian Moyer

Prodigy 140 points

Sure

0 Christian Moyer 6 months ago in reply to Vaibhav Khatri

TI__Mastermind 31366 points

Hello Vailbhav,

Vaibhav Khatri said:
Okay, so BQ25798 have a path leading to PMID, but is it same in BQ25792?

Cause BQ25798 can provide power on PMID in cases of VBUS absence but can BQ25792 can also do the same?

Yes, I confirmed you can support a load on PMID or VBUS in OTG mode. Backup up the charger automatically changes the converter's operating direction to reverse/OTG/source (from forward/charge/sink) so that the battery can provide a regulated voltage at PMID. If you are okay with manually turning on OTG mode when adapter is removed, then BQ25792 will work.

Best Regards,

Christian.

0 Vaibhav Khatri 6 months ago in reply to Christian Moyer

Prodigy 140 points

Thanks.
How long does the mode switching takes? cause in my application i need switching in few milli seconds

Best regards

Vaibhav

0 Christian Moyer 6 months ago in reply to Vaibhav Khatri

TI__Mastermind 31366 points

Hello Vailbhav,

Vaibhav Khatri said:
cause in my application i need switching in few milli seconds

Then I would highly recommend using BQ25798 with backup mode. OTG is not meant for fast switch over.

In OTG, you have to wait for VBUS to drop below VBUS_UVLO, Then send a command to enable OTG, Then wait for the converter to start up (around 5ms).

Best Regards,

Christian.

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BQ25798: Substitute