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Originally Posted by bigbop
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Close - check the USB host schematics from the Intel eval sheets (pg29) and you will see that there are two control lines going to the MAX1693 USB power control chip. One is the over current sense output to the CPU (USBHPWR) and the other turns on (or off in the case of an overcurrent condition) the 5V to the external device (USBHPEN).
We probably don't need those signals. However, we DO need a signal conditioning/transient-protection device similar to the STF201 USB interface chip between our external device and the CPU.
One interesting observation from those schematics on page 29 - note the 15K pulldown resistors...:approve:
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Totally agree.
What I am wondering if I CPU needs a HIGH at USBHPWR (LOW means fault) to turn on data flow. I do not think so, CPU should use that input just to set USBHPEN output.
Yeh!, pull down resistors are the same at page 29.