PCF8574A INT Problem

Hi,

I have Building a 24 Inputs Alarm Device,all is working fine,but :-) i have just a little Problem
when I have a Voltage on one Pin between the HI and LO PDF Specification the INT is still remaining LOW and is blocking my complete INT.
I use a 10K Resistor on the Interrupt Line,and a Voltage divider like on the Picture.

Thank You for any Help

Regards Pesti.

I forgott to say that this Problem is happen just when the voltage is slow decreasing!
I think that I should use a Schmidt Trigger between Input and pcf8574A.

Regards Pesti

Quote:

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Originally Posted by Pesticida

I forgott to say that this Problem is happen just when the voltage is slow decreasing!
I think that I should use a Schmidt Trigger between Input and pcf8574A.
Regards Pesti

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Or use a high value pullup resistor...unless it's that slow voltage drop that you're looking for.

Hi Skimask,

No I'm not looking for Slow Voltage drop,I need a Secure Alarm Device,this was just a coincidence that I found this Error.

I can use the Device in two Mode :

Mode1 = On/Off to Ground
Mode2 = Voltage On/Off Between 5-15 Volt

The Problem is that when the Input Pin Voltage is going Slow from High to ~ < 1.9 Volts then the INT switch to Low and is remaining Low.

Regards Pesti