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Design >> Analog Design >> Why fault indicators are open-drain outputs?
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Message started by jsaenznoval on Oct 7^th, 2014, 6:33am

Title: Why fault indicators are open-drain outputs?
Post by jsaenznoval on Oct 7^th, 2014, 6:33am

Hi everyone,
I'm designing a switch with a digital controller that monitors fault conditions (Over current, Over/Under voltage, Thermal Shutdown, etc).
Why are commonly used open-drain outputs as external interface of fault signals?

Thanks!

Title: Re: Why fault indicators are open-drain outputs?
Post by loose-electron on Oct 9^th, 2014, 11:38am

So that the end user can attach a pull up resistor to the same power supply as the device that the output is feeding unto.

Net result of logic high low from ground to the Vcc of the digital device that you are feeding a signal to.

Example - got a Boost converter running off of 15V power and you want to feed the overcurrent indicator to a logic ASIC with 1.8V power.