BQ25150: LS/LDO output not working on power up from battery

user4052185

Prodigy 230 points

Part Number: BQ25150

Hi,

i am powering BQ25150 from battery (own standalone pcb without I2C connections).

1) When pressing /MR line down for a period battery voltage is seen on PMID. However, LS/LDO output is showing 0V.

2) When powering same pcb from VIN LS/LDO is powered to 1.8V.

3) On battery powered case, when i set /LP line "HIGH" temporary or permanently, LS/LDO output startsup to 1.8V. When pulling "LOW" again /LP line LS/LDO keeps 1.8V.

Only removal of the battery will set BQ25150 back on step 1) again.

What could explain this behaviour? My previous PCB with some small differences LS/LDO starts up normally from battery only as well without need of /LP "HIGH"

over 3 years ago

0 Gautham over 3 years ago

TI__Genius 12485 points

Hello,

Can you share your schematic for the BQ25150 portion and also the connections to the VINLS pins? VINLS is the input to the LDO so is it connected to PMID?

Regards,

Gautham

0 user4052185 over 3 years ago in reply to Gautham

Prodigy 230 points

Here is the schematics

0 user4052185 over 3 years ago in reply to user4052185

Prodigy 230 points

Can it be happening due to the timing of /MR release? In previous design this autostart function (exit from shipping mode) in case of battery insertion (logic on /MR pin), CHARGER_/MR was released by external regualator, thus a few milliseconds latert than now using VBAT_SYS (PMID)

0 Arelis Guerrero over 3 years ago in reply to user4052185

TI__Expert 5645 points

Hi,

The MR has to be held low for Twake2 and then release in order for the device to exit ship-mode. Plugin VIN will also exit ship-mode. Can you provide a scope plot with the MR, LDO, PMID (VINLS), and BAT signals when connecting battery?

Regards,

Arelis G. Guerrero

0 user4052185 over 3 years ago in reply to Arelis Guerrero

Prodigy 230 points

I will attach plots sooon.

Meanwhile, when battery inserted, PMID is used to release /MR from "LOW", and PMID rises up to BAT normally. LDO is not powering up until /LP pins is driven high.

So based on PMID behaviour it exists from ship mode but LDO behaviour is strange (reacting to /LP).

0 Arelis Guerrero over 3 years ago in reply to user4052185

TI__Expert 5645 points

Hi,

Perfect, thanks. I'll be waiting on the plots to continue the support. When trying a BQ25150 unit on the lab I see both the PMID and LDO being powered after waking out of shipmode. You mentioned you had a different supply (external regulator) powering out of ship mode before, did you observed the same behavior (LP vs LDO) or is it only after the schematic changes to use PMID instead when this is happening?

Best regards,

Arelis G. Guerrero

0 user4052185 over 3 years ago in reply to Arelis Guerrero

Prodigy 230 points

With external regulator driving CHARGER_/MR on my schematics, LS/LDO rises up normally.

It seems that something internal timing related thing of BQ? Eventhough LS/LDO does not rise up, BQ reacts to I2C communication(/LP toggle) and this input make LS/LDO output rise up.

0 Arelis Guerrero over 3 years ago in reply to user4052185

TI__Expert 5645 points

Hello,

Do you know the timing it was taking before with the external regulator vs the timing is taking now? I'll like to try to replicate your setup on my end. Also having the scope captures will help out to see if something does not seems okay.

Regards,

Arelis G. Guerrero

Power management

Power management forum

BQ25150: LS/LDO output not working on power up from battery