• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Subscribers 63 subscribers
  • Views 1954 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

BQ25890H: Using in OTG mode

Sergey Byshlakov
Prodigy 60 points
Part Number: BQ25890H
Other Parts Discussed in Thread: BQ25890, BQ25895, TPS2514A, TPS2546

Can I use the BQ25890H in OTG mode as a charging device? For example 5V 1,5A.
Is it possible to short-circuit the conclusions of D + and D- with BQ25890H?
Thank you

  • 0
    TI__Expert 8230 points
    Hello Sergey,

    The bq25890H can only operate in one mode at a time, either buck or boost mode. This means that when the device is configured as a charger, the switching converter will be in buck mode powering the SYS output and charging the battery. When in OTG mode, the converter is operated in reverse to provide the 5V output at VBUS.

    If you want to fix the D+/D- detection result to always detect DCP, you can short the D+/D- lines. However, if you short these lines, you won't be able to drive the programmable DACs on the D+/D- lines in the event you want to handshake with a HVDCP adapter. I recommend also reviewing the bq25890 or bq25895 which don't have the programmable DACs but still provide D+/D- detection.
  • 0 in reply to Fernando Lopez
    Prodigy 60 points

    Thanks for the answer.
    I want to enable bq25890h by this scheme:

    At the ID signal, I will recognize which type of device I connect to the USB. If the ID is floating, then SDP / DCP / CDP is connected to the USB. If the ID is connected to GND, then I want to include a boost mode and apply for 5V VBUS voltage and current up to 1.5 A, ie be a charger (Dedicated Charging Port). The question is, can bq25890h short-circuit D + and D- to be defined as DCP?
    Sorry for the bad english.

  • 0 in reply to Sergey Byshlakov
    TI__Expert 8230 points

    Hello Sergey,

    Yes, you can short the D+/D- lines to force the bq25890H to detect DCP always for input current limit when in charge mode. You can short them or use a 200Ohms in between the lines.

    When in OTG mode, you would configure the boost mode output in REG0A which lets you set the OTG current limit and the output voltage. Closest current limit for your requirements would be 1.4A.

    The device connected to the USB port expecting to see a DCP would need to see the correct D+/D- termination (in this case a short).

  • 0 in reply to Fernando Lopez
    Prodigy 60 points
    Hello Fernando,
    I understand that I can short circuit D + and D- or put a resistor up to 200 Ohm, but I'm interested in another question. Can the BQ25890H independently shorten the pins D + and D- in the booster mode without using external resistors?
    I need the BQ25890H to work in two modes:
    1) Charge the internal lithium-ion battery with the definition of the type of the connected port according to the signals D + and D-;
    2) Charge external devices (eg mobile phone), emulating DCP.
    Enable boost mode if Pin ID is shorted to GND.
  • 0 in reply to Sergey Byshlakov
    TI__Expert 8230 points
    Hello Sergey,

    The bq25890H cannot short the D+/D- lines on it's own. The bq25890H can generate various voltage thresholds on the D+/D- for HVDCP handshaking, but it cannot short the D+/D- lines internally or perform the enumeration for any external device connected.

    The external device connected during OTG will be expecting a DCP, it would need to see the D+/D- lines shorted for it to know how much current it can draw.

    Since the application requires to switch the D+/D- lines according to the state of the ID pin, you would need a USB port controller such as the TPS2546. If no data will be needed to be exchanged with the host, the TPS2514A is a good alternative.
  • 0 in reply to Fernando Lopez
    Prodigy 60 points
    Hello Fernando,
    Thanks for the help.
    Considering that for OTG operation as a charger of external devices we need to short-circuit the lines D + and D-, we can use the simplest analog multiplexer.