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TPS2543

Calum Mackinnon
Genius 4155 points
Other Parts Discussed in Thread: TPS2511, TPS2546

I have configured the TPS2511 to limit current at 500mA (min). If a device is plugged in that has a very low battery, it will assume that I can supply more than the 500mA since it negotiates as a DCP. The problem is that the voltage drops across the FET enough to trigger a device shutdown. This will loop when the devices turns back on.

I also read in the TI forum that

http://e2e.ti.com/support/power_management/power_interface/f/204/t/240121.aspx

So, I am now looking at the TPS2546 now so I can force the SDP mode. However, the datasheet states:

Standard Downstream Port (SDP) USB 2.0/USB 3.0

An SDP is a traditional USB port that follows USB 2.0/3.0 protocol and supplies a minimum of 500mA/900mA per

port. USB 2.0/3.0 communications is supported, and the host controller must be active to allow charging.

I don’t have a host controller since this is just like a wall charger. Do you think this configuration would still allow charging?

 

Calum

  • 0
    TI__Mastermind 42795 points

    TPS251x is probably the best choice for a wall charger application, but you could use TPS2546 as well. But, with the current limit set at 500mA, you will have the FET foldback issue with both (DCP mode). If you use TPS2546 configured for SDP (via the CTL pins), then there are some portable devices which will not charge if they detect an SDP host (through the handshake with the TPS2546) and cannot establish USB 2.0 communication with the controller. Many portable devices can slow charge, but there are a few which cannot.

  • 0 in reply to Eric Wright
    TI__Prodigy 650 points

    When TPS2511 is used with 500mA current limiting, which device with low battery can pull it into thermal shutdown?

    Is the D+/D- configured 10.5W mode? I would sugguest configure D+/D- 5W mode, with D+/D- fliped and connected to connector and keeps ILIM at 500mA.

    TPS2511 is continious current limiting, with 500mA, in order to make it thermal shutdown, the Output Voltage must be pulled down to very low voltage. It can happen with electrical load test, whcih will pull output voltage very low. But with portable devices, they all have limitation of lowest votlage they can accept. As their battery requires 3.0V-4.2V, usually 4.xV is the lowest voltage device can accept. Some special phones, like Moto phones may accpet lower. In general, we found it quite different to have portable devices to pull power switch into thermal shutdown.

  • 0 in reply to Vincent Wang64858
    Prodigy 10 points

    The charger is configured at 5W with the D+/D- flipped and the current limit is set to 500mA (min).  The absolute max current draw is about 580mA, and the TPS2511 will shutdown once the output voltage reaches about 4.1V.

    An iPad Mini with a dead battery will draw 580mA and the output voltage is at 4.28V. The TPS2511 heats up a little but still seems to function in continuous current limit. A dead battery on an iPad Retina was causing the TPS2511 to continually reset. Perhaps this is due to the inrush as the screen turns on to display the charging icon?