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BQ25601: REGN voltage with Vin = 12V, Using 9V input voltage

Jason Petras
Intellectual 650 points
Part Number: BQ25601

Hi Charger Experts, 

I have two questions:

1. What is the REGN voltage when Vin is 12V? Datasheet only specs 5V and 9V input.

2. Using 9V or 12V as Vin has a gotcha/showstopper: The default REG06, OVP[1:0] bits are set to 6.5V by default - meaning that the part is disabled (no powerpath, no i2c) if you have a dead/missing battery and a 9V, 12V wall wart. This is a big deal. Is there going to be a fix for this? If not, can you please at least update the datasheet so that this nuance is in bold?

Thanks!

Jason 

  • 0
    TI__Guru 54651 points

    1. REGN is a 6V LDO. For 12V input, VREGN=6V.

    2. If powering up the device with 9V or 12V input, although the device will be in input OVP, the device can still communicate via I2C. User may use a LDO from 9V or 12V to support I2C pull-up voltage. Then the input OVP setting can be modified right after 9V or 12V starts up and charger will operate normally.

    Thanks!

  • 0 in reply to Ning T
    Intellectual 650 points
    Hi Ning,

    Thank you for the answers. I would like to discuss #2 further...

    1. Thank you on 12 Vin = 6 VREGN

    2. This doesn't quite solve the problem. Since the switcher is disabled during OVP, I would need an LDO for the i2c pullups *and* my mcu which is normally connected to the charger's SYS pins. The goal is to be able to operate without a battery (or fully depleted battery) when a >6V wall adapter is plugged in. Adding extra LDOs sorta defeats the point of this (otherwise) wonderfully full featured charger.

    Unfortunately, I have to ask the same question: Is there going to be an update to this charger? If not, can you please update the datasheet to point this requirement out? Again, you lead the datasheet saying that it's 9V, 12V compatible. However, a 5V source is required if the battery is missing or fully depleted before the charger operates correctly again. This is a problem since 99% of wall adapters are fixed voltage.

    Thanks Ning

    Jason
  • 0 in reply to Jason Petras
    TI__Guru 54651 points
    This is more an application question about how to support the pull-up voltage for I2C. I have passed your feedback to the related personnel and they will research and make the decisions. Thanks!
  • 0 in reply to Ning T
    Intellectual 650 points

    Thank you Ning!