Part Number:TPS2561
Hi,
I am using TPS2561 for current limiting of USB Ports. TPS2561 enable input pin is controlled by Hub controller TUSB-4041I. Output is terminated to USB2.0 connector for sourcing current to external load which is very low load something like pendrive or optical mouse.' FAULT1 & FAULT2 pins are connected to overcurrent input pins of USB Hub controller.
I have designed for ILIM with 25.5K as current limiting resistor which should be much more than enough to drive external load up to 1A(Theoretically it should drive up to 2.4A).
the Problem is whenever I connect any USB device to the Ports, TPS2561 gives overcurrent fault. Due to Over current fault detection, the Hub controller sets the enable inputs TPS2561 to low. I have tested by varying current limiting resistor R67(in above figure) to different values and all the time behavior is same for all range of resistors. I have checked the load current requirement by bypassing the input power from external source and found that load draws just 40-50mA which is much lesser load. But this much small load is also detecting as overcurrent by this IC which results in shutting down the output power of TPS2561.
Can anyone please tell what may be bug in the design? I have repeated this experiment in 3 boards and all behave the same. With external power, hub is able to detect the external USB device but with TPS2561, its not detecting.
Thanks.