Hello,
I have used the TI TPS2561 current limited power switch on two different designs.
It has worked well for me using the switch on a four port USB Hub with a Panasonic NN31001A-BB DC/DC converter switching at 800kHZ .
However, I'm having problems right now using it for a seven port USB Hub board using a VISHAY SIC471 power supply switching at 300kHZ.
The ILIM resistor is set to 48.7K.
When I power the card using VBUS or a 5VDC external supply bypassing the VISHAY SIC471, I see the switch work as intended. The FAULT pin toggles low when I apply a 1.2A load and the Cypress HUB controller disables the EN Pin. In turn I get a over current status on a LED from the HUB controller.
When I am powering the card with a external power (12-24VDC) and dropping voltage down to 5VDC using the VISHAY SIC471 switching power supply, I never see the FAULT pin toggle low when I apply a 1.2A load. The voltage OUT just droops down to 1.48V. If I increase the current load it eventually triggers the fault pin as the voltage begin to drop even lower, but not at the expected current.
Please advice on what can be causing the FAULT pin not to toggle on a over current.
Thanks!
