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Best way to provide power for charging USB port

Oli
Prodigy 80 points
Other Parts Discussed in Thread: TPS62110, TPS2541

Hi all,

I have a 12V battery and I wish to provide a USB port on the product that allows just charging. It should be able to charge all standard USB devices, including the iPod and iPhone.

The battery isn't huge, so it has to be a switching regulated system for efficiency. It should only use significant power (>200uA) when a USB device is plugged in - whether this is by detecting when a device is plugged or having a very low quiescent current doesn't matter. I've had problems because all the solutions don't appear to be able to 'shutdown' when a device isn't plugged in or they use too much current all of the time.

What solutions do you think are suitable?

Thanks in advance.

  • 0
    TI__Guru**** 150770 points

    It sounds like all you are looking for is a 12V to 5V (USB) converter.  The power quick search at power.ti.com can provide many recommended ICs that meat your requirements.  The TPS62110 when operated in PFM mode will give less than 200 uA of input current when there is no load on the output.

    Our power interface products provide USB load switches to protect the USB port if you desire that.

  • 0 in reply to Chris Glaser
    Prodigy 80 points

    Hi Chris

    thanks for your reply, I don't think I explained myself clearly enough. Some devices actually require things to be present on the D+ and D- lines for them to charge (like apple devices for example) and I don't want to take an undocumented gamble by just seeing what works to charge what devices. 

    The TPS2541 takes care of these duties so it provides compatibility. Obviously I can't run this all the time, so I was hoping there would be a way to 'detect' when the USB plug is in and enable / disable the 5V. 

     

     

  • 0 in reply to Oli
    TI__Guru**** 150770 points

    Yes, you will need multiple devices for this--a power converter (TPS62110), USB power switch with the necessary detection for the Apple stuff, maybe a small uC to control the primary side, and a USB charger (this is most likely integrated in the secondary devices).  So, are you just trying to get your power consumption when idling down to a low level?

    You can post to the power interface forum to see if that team has a simple way to turn off their part when there is nothing connected to the bus.  But the TPS62110 running with no load will draw very little current, so it can convert the power for the USB port while keeping high standby efficiency.