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bq 24196. Charging&OTG Simultaneously

Luis Gomez1
Prodigy 10 points
Other Parts Discussed in Thread: BQ24196, BQ24195L, BQ24195, BQ24192, BQ24292I

Hi everybody, 

I am currently using the chip bq24196. I am trying to guess why this chip can not support Charging and OTG simultaneously by using a Y USB cable.

I guess that it is something connected with the working modes of the chip. Once a OTG device is detected, the chip works on "boost" mode and charging is not allowed. I know that some devices as Sony xperia mobiles allow both functionallities at the same type, so I guess that they are using somehow and "hybrid" mode which allows charging and OTG conection simultaneously.

Can anyone give me a hint about this topic or suggest me any chip which allows charging and OTG simultaneously?

Thanks in advance to everybody.

Regards,

Luis. 

  • 0
    TI__Intellectual 1910 points

    Luis,

    The bq24196 only support independent charge or OTG , but not both at the same time. The converter can only operate in buck or boost mode by reusing the internal circuit and external inductor). For end equipment to support both charging and OTG, please consider bq24195 or bq24195L. The device can output USB input to PMID pin, while charging battery at the same time by management the power priority.

    -sam

  • 0 in reply to SamW2000
    TI__Mastermind 25546 points

    hi Sam,

    I have a customer willing to use the BQ2419x.

    I have then a few question, since datasheet is not very clear to me:

    - in boost mode the 5V generate will be presented to VBUS, that means we have to provide external oring diode to separate the normal input (VBUS) to the 5V provided by the boost to supply the 5V device that will be connected to the same rail, right?

    - what happens when VBUS "comes back" from the off state and how device manage to go back in normal mode (no boost)?

    - device enters in boost mode (once all the conditions are met) in 220msec. What about the other time/delay (i.e. after which device is back to normal mode)?

    many thanks in advance

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    TI__Mastermind 25546 points

    PS: BQ24192 and BQ24195 will be the same under this point of view?

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    TI__Intellectual 1910 points

    Vincenzo,

    Thanks for choosing bq2419x family charger. Please see my comment below:

    - in boost mode the 5V generate will be presented to VBUS, that means we have to provide external oring diode to separate the normal input (VBUS) to the 5V provided by the boost to supply the 5V device that will be connected to the same rail, right?

    It depends on the application, do you have a block diagram of what the customer wants to accomplish. For bq24196, the VBUS can be connected to a power source which would supply 5V to the bq24196 charger, or the charger can output 5V using USB OTG mode and provide power. In most application, the host will need to manage the OTG mode to turn it on/off based on USB ID pin. In the bq24195 for power bank application, there is a requirement for VBUS front end external circuit which manage the automatic turn on/off of OTG based on adapter detection.  

    - what happens when VBUS "comes back" from the off state and how device manage to go back in normal mode (no boost)?

    Please see above for different device.

    - device enters in boost mode (once all the conditions are met) in 220msec. What about the other time/delay (i.e. after which device is back to normal mode)?

    The boost mode is turned off immediate (<1 ms) once OTG pin goes low or OTG Mode is disabled in i2c.

    many thanks in advance

    Regards,

    Sam

  • 0 in reply to SamW2000
    TI__Mastermind 25546 points

    thanks a lot Sam,

    still 2 riddles are bothering me:

    a) why device need 220msec to enter in boost mode and only 1msec to get out? even considering a huge SS time, 220msec seems to me an ethernity...

    b) what's the purpose of PMID pin?

    thanks a lot in advance

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    TI__Intellectual 1910 points

    Vincenzo,

    a) The 220ms includes power source detection, REGN power up, and charge pump power up etc. For USB charging application, the delay is usually acceptable. Is there a particular need/reason for faster boost mode enable? If so, we have a new device in the family (bq24292i) released last week which has boost mode delay of 30ms. I would also highlight that since the bq24292i is a 4.5A, the price is going to be higher.

    b) The PMID has a decoupling cap that supply instantaneous current to the converter. Please see the datasheet block diagram for how it is connected inside the IC.

    Regards,

    Sam