+ Post New Thread
Results 1 to 6 of 6
  1. #1
    Advanced Member level 1
    Points: 3,240, Level: 13

    Join Date
    May 2013
    Posts
    424
    Helped
    82 / 82
    Points
    3,240
    Level
    13

    USB current negotiation

    Hi all,

    I'm working on a design that draws power through USB but needs about 1.5A of current at 5V. Hence I'm exceeding the 500mA limit and need to "negotiate" a higher current from the source. I've read various pieces of USB documentation and I understand a small microcontroller would be the way to do this properly. I'm looking for a solution that doesn't require me to implement custom embedded software, however.

    Does anyone know of any custom ICs that negotiate a higher current with the host? Ideally I'm looking for a single chip solution that allows the current to be negotiated to be programmed with an external resistor or something similar.

    Note: my on board power system is only compatible with 5V so I can't use the C-type controllers that pull up the voltage to 20V.

    Thanks for any recommendations or advice, as usual!

    •   AltAdvertisement

        
       

  2. #2
    Super Moderator
    Points: 80,975, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,421
    Helped
    3728 / 3728
    Points
    80,975
    Level
    69

    Re: USB current negotiation

    Hi,

    The most important is: you need a USB DCP which can supply 1.5V.
    There is the USB specification, various application notes and forum discussions. What else do you need?

    And for sure there are ICs from various manufacturers to find out current capability if an USB supply/host..
    If I'd want to find some I'd use an internet search or an internet catalog from a distributor.

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



    •   AltAdvertisement

        
       

  3. #3
    Advanced Member level 1
    Points: 3,240, Level: 13

    Join Date
    May 2013
    Posts
    424
    Helped
    82 / 82
    Points
    3,240
    Level
    13

    Re: USB current negotiation

    After searching over an hour and browsing through many datasheets and application notes, I've come to the conclusion that a BC 1.2 slave controller IC does not exist without I2C or other digital control features.
    Hence there is no single chip solution for the application I'm looking for.



    •   AltAdvertisement

        
       

  4. #4
    Super Moderator
    Points: 80,975, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,421
    Helped
    3728 / 3728
    Points
    80,975
    Level
    69

    Re: USB current negotiation

    Hi,

    It took me 5 minutes to find MAXIM's USB Host Adapter Emulators
    They may or may not have I2C. Some may have, but you don't need to use it (as stand alone solution)
    Other manufactureres have compareable parts.

    Maxim has a lot of documents and application notes about USB and charging...read through them

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



  5. #5
    Advanced Member level 1
    Points: 3,240, Level: 13

    Join Date
    May 2013
    Posts
    424
    Helped
    82 / 82
    Points
    3,240
    Level
    13

    Re: USB current negotiation

    Quote Originally Posted by KlausST View Post
    It took me 5 minutes to find MAXIM's USB Host Adapter Emulators
    They may or may not have I2C. Some may have, but you don't need to use it (as stand alone solution)
    Other manufactureres have compareable parts.
    As the name Host Adapter implies, these are parts intended to regulate power to a slave device on the host side. I'm looking for the equivalent handshaking part for the slave side.



    •   AltAdvertisement

        
       

  6. #6
    Super Moderator
    Points: 80,975, Level: 69
    Achievements:
    7 years registered
    Awards:
    Most Frequent Poster 3rd Helpful Member

    Join Date
    Apr 2014
    Posts
    16,421
    Helped
    3728 / 3728
    Points
    80,975
    Level
    69

    Re: USB current negotiation

    Hi,

    You are correct. My copy and paste fault.

    It should be: MAXIM USB CHARGER DETECTORS.
    https://www.maximintegrated.com/en/p...interface.html ... scroll down to the technical documents

    Klaus
    Please donīt contact me via PM, because there is no time to respond to them. No friend requests. Thank you.



--[[ ]]--