What is the maximum input voltage for the Counter/Timer on the KUSB-3100, KUSB-3102, KUSB-3108 and KUSB-3116?
USB Modules: KUSB-3100 Series: KUSB-3100, KUSB-3102, KUSB-3108, KUSB-3116
Question:What are the maximum and minimum input voltages for the Counter/Timer on the KUSB-3100, KUSB-3102, KUSB-3108 and KUSB-3116?If I supply a square wave of 15Vpk-pk, will the input circuitry clamp the input to be compatible with the HCT levels or will it be damaged?
Answer:There are protection diodes 74HCT14 to +5V and GND. There are also 4.7K ohm resistors on the Counter/Timer inputs.The inputs are +5V tolerant and will be ok with a back EMF voltage (22 ohm resistor is in place) from driving a relay and will tolerate the 4KV-150pF ESD pulse but will be damaged with a 15V Square Wave.
Copyright 2003, Keithley Instruments, Inc.
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