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griffin1701's avatar
griffin1701
Icon for New Contributor rankNew Contributor
1 year ago
Solved

More info needed regarding Schmitt Trigger input setting in Max-V CPLD

I am looking for the center voltage value for a pin on the Max V CPLD, when it is configured as a 3.3V Schmitt trigger input. The datasheet shows a hysteresis voltage of 400 mV for Vccio = 3.3V, but...
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  • AqidAyman_Altera's avatar
    AqidAyman_Altera
    1 year ago

    Thank you for the input, Frank.


    Do you have any more help needed on this issue?


FvM's avatar
FvM
Icon for Super Contributor rankSuper Contributor
1 year ago

Hi,

unfortunately MAX V datasheet (neither other CPLD or FPFA datasheets) give typical threshold voltage for 3.3V IO-standard, you can assume that it's somewhere between Vil,max of 0.8 V and Vih,min of 1.7 V. 3.3V ST thresholds have in case of doubt +/- offset to lvcmos33.

To evaluate typical ST thresholds, you'll need to make your own measurements. You can e.g. setup a slow RC ST oscillator and measure reversal points.