topic KV30 Input Protection in Kinetis Microcontrollers

KV30 Input Protection

dillonkopecky — Wed, 12 Oct 2016 13:00:57 GMT

The datasheet for the KV30 implies that inputs are protected from a positive overvoltage if a current limiting resistor is used:

"All analog and I/O pins are internally clamped to VSS through ESD protection diodes. If VIN is less than VIO_MIN or

greater than VIO_MAX, a current limiting resistor is required. The negative DC injection current limiting resistor is

calculated as R=(VIO_MIN-VIN)/|IICIO|."

However testing this with a 100k input resistor, the device does not seem to clamp the input voltage (tested up to 6.5 V which is well in excess of the 'VIO_MAX'). This makes sense since the datasheet also says that pins are only clamped to VSS, so I am wondering if the inputs are actually protected from overvoltage events like implied.

Re: KV30 Input Protection

Hui_Ma — Mon, 17 Oct 2016 03:18:07 GMT

There is a similar thread about input voltage positive overvoltage requirement and protection circuit with below link:
https://community.nxp.com/thread/433880

The input voltage should not exceed with datasheet requirement a max. value 3.8V.
There requires an external diode to VDD, Injected current must be limited to prevent disruption to the internal supply rails.

Wish it helps.

Have a great day,
Ma Hui
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