CPLD Controlled Door Lock - Input Circuit

25 Apr 2015

Input Circuit

The input circuit is very simple. Consider that 24V is present at the connector X1-1; this will allow 20mA to flow through LED1 and indicate there is an input present. Approximately 2mA will flow via R2 and R3, thereby pulling the CPLD IN01 pin to 3V (the device can accept unto 4V).

Top Comments

michaelkellett over 11 years ago in reply to oldmanraskers +1

You're mixing up output drive currents and input currents. The MAXV will draw a tiny 10uA current on an input (unless you program a pullup current for that pin) so when Q1 is off you would expect to see…

oldmanraskers over 11 years ago

I know there is no junction at IN01 but I have since fixed it.
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clem57 over 11 years ago

Good now
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oldmanraskers over 11 years ago in reply to michaelkellett

I've uploaded it here as JPEG - hopefully that will make some difference.
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michaelkellett over 11 years ago in reply to oldmanraskers

Try putting it into a discussion post for now - or give us a Dropbox link if you use Dropbox.

MK
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oldmanraskers over 11 years ago in reply to michaelkellett

Not sure what has happened here - I did embed the image via the camera icon
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