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As shown in above figures above, a comparator is outputting 16V pulse signal when it is ON.

For some reason I want to lower this voltage around 8V pulse. In Config 1, it is coupled to a voltage divider. In Config 2, it is coupled to a zener clamp. This final 8V pulses will then be coupled to a DAQ which will count the pulses. The reason of stepping down the voltage is that the DAQ has 10V input limit. The DAQ has input impedance 100Gohm.

I can use both Config 1 and 2. But is there an advantage of one configuration to another? Which one would you use and is more convenient?

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  • \$\begingroup\$ what compartor? \$\endgroup\$ – Jasen Mar 2 '16 at 9:57
  • \$\begingroup\$ general comparator or schmitt trigger. \$\endgroup\$ – user16307 Mar 2 '16 at 9:59
  • \$\begingroup\$ so nothing at all like an ordinary comparator like LM319 then? \$\endgroup\$ – Jasen Mar 2 '16 at 10:10
  • \$\begingroup\$ yes it doesnt matter, imagine a schmitt trigger or compa ator has 16V 0V pulse train output. The rest is the question. Coupling config to the DAQ. \$\endgroup\$ – user16307 Mar 2 '16 at 10:11
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Either choice will work.

Configuration 1 is cheaper, both in component costs and PCB area, so I'd probably go with that.

If the pulses are very narrow, the transient response of configuration 1 is also better, since a zener will have greater stray capacitance, but that's likely not a concern, since really narrow pulses should probably have some sort of detection circuitry.

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resistors are better behaved than zeners at low power (and also cheaper) go with the resistive divider.

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