0
\$\begingroup\$

I am using USB2517 - USB 2.0 Hi-Speed 7-Port Hub Controller IC to make a USB 2.0 hub.

What I do not understand (or its missing from the IC's datasheet), is Pins OCS[7:1]_N, which are "Input from external current monitor indicating an over-current condition".

overcurrent active low or high

I do not understand if that pin is Active Low or active high. Do I need to send a 0V signal to indicate there is no overcurrent, or a 3.3V signal to indicate there is no overcurrent?

As a note, the datasheet says this pin has a internal pull up resistor, but this does not help me understand what level signal I need to send to activate the overcurrent condition.

I guess since there is a internal pull-up, then 0V are used to indicate overcurrent?

This information from the datasheet is either missing or its plain obvious.

Otherwise, I will have to contact microchip to ask for support.

\$\endgroup\$
2
  • \$\begingroup\$ Even if _N suffixes are not given, the {Note} gives a clue: Since those terminals are inputs with internal pull-ups, they see logic-hi when left floating. So it's obvious that the inputs should be active-low. \$\endgroup\$
    – Rohat Kılıç
    Sep 24, 2021 at 9:46
  • \$\begingroup\$ I know, I was thinking about that, but I then said "wait, what if the IC wants to keep the overcurrent protection passively active by pulling the pin high?" \$\endgroup\$
    – Christianidis Vasileios
    Sep 24, 2021 at 9:49

1 Answer 1

Reset to default
1
\$\begingroup\$

The _N typically indicates 'negated' and thereby it is active LOW.

\$\endgroup\$
1
  • \$\begingroup\$ Okay, it was plain obvious. Thanks! \$\endgroup\$
    – Christianidis Vasileios
    Sep 24, 2021 at 9:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.