# Digital input of high voltage

1. ## Digital input of high voltage

Hi i need a square input for my digital input application from function generator but a voltage of 150V and frequency of 35kHz .. our module accepts only digital input .. kindly help me with an interface circuit between function generator and module

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2. ## Re: Digital input of high voltage

is the 150V the input or desired output?

if 150V is the input, what is the desired output?
if 150V is the output, what is the desired input?

what voltage levels for digital input? TTL? CMOS? 3V? 3.3V?

is the frequency alwatys 35 kHz, or is the frequency variable?

is the duty cycle 50% (square) or is the duty cycle variable?

what are the desired rise and fall times?

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3. ## Re: Digital input of high voltage

Hi,

150V is the input range to my module needed to test. It has a range from 15-150V.
If 15-150v is input then nodule read as 1 else 0.
Input shal be given frm function generator as it has a capacity to vary frequency.
Frequency is variable from1k to 35k
Duty cyle 50% would be enough
Rise and fall times should be as minimum as possible. Its just like i can test with function generator but it does not support enough voltage to test..

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4. ## Re: Digital input of high voltage

Hi,

Resistive voltage divider
Comparator.

Sadly you don't give the expected output voltage levels, and you don't give information about your power supplies voltages.

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You have two options:
* either calculate the voltage divider that 150V input gives output in the range of your comparator's input voltage range (which usually depends on supply voltage)
* or you focus on the 15V switching level and use a limiter (zener diode...) to limit the output voltage at higher input voltages.

The first one has the benefit that you easily can adjust threshold level,
The second one gives a more precise threshold level.

Klaus

Rise and fall times should be as minimum as possible
This is no useful specification. Give a value.

5. ## Re: Digital input of high voltage

Can i use a mosfet switching circuit for this requirement but i think rise and fall times would be more at high frequencies

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6. ## Re: Digital input of high voltage

Hi,

Generally: Yes, but...

How? What circuit? Why?

Klaus

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