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I have a programmable f/I converter which can be modified for various types of inputs and outputs. They have also a more detailed manual. I read them and learned how to configure and set this device. As an output I set it to 0-10V and as input I set it for frequency with TTL type input. This is because for NPN and PNP inputs I need to add some transistor circuitry with certain voltage ect. Input to the converter will come from a circuit which is currently outputting 0-8.2V pulse train(8.2V is because of a zener limiting the amplitude)

Anyway the bottom line is I will use this converter to convert incoming pulse train from a circuit to analog voltage. And my inputs to the converter is 0-8.2V pulse train(input to pins 5 and 6 in the datasheet). I made the setup and works fine. The converter successfully converts 0-8.2V pulse train frequency to a voltage range set. I set the converter to TTL input as I mentioned.

My concern is coming from lack of knowledge here. So the input to the converter is a pulse train with 8.2V amplitude, on the other hand the converter is set to TTL input settings. But my input to the converter is 0-8.2V not 0-5V.

Is it alright to use this like that? I mean would exceeding 5V and using 8.2V amplitude pulse train cause damage in long run? I know that TTL stands for 0-5V signals. Should I reduce my input pulse amplitude to exactly 5V? I couldn't extract this from the manual from the max ratings.

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The manual does not give absolute input limits, so there is no way to tell if 8 volts will kill it. As a result, you should assume that it will. And be careful how you reduce the voltage. Simply using a voltage divider can get you into trouble if you use resistances which are too large.

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