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griffin1701's avatar
griffin1701
Icon for New Contributor rankNew Contributor
11 months 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
    10 months 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
11 months 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.