Series Limiting Resistor on Inputs | Cypress Semiconductor
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Series Limiting Resistor on Inputs
Is it recommended to use current limiting resistor for feeding data into PSoC?
Yes, if the input voltage is expected to go beyond VDD, it is recommended to use current limiting resistors on the input pins. The PSoC GPIO has got internal clamping diodes which will protect the GPIO. The current through these clamping resistors should be limited to about 5mA. For example for an input voltage of 30V and Vcc of 5V, a series resistor of atleast 5K should be used.