Port Input / Unused Pins / Latch-Up; Port Input / Unused Pins - Fujitsu ALL FR 460 Series Application Note

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FR460 Hardware Set Up

Chapter 3 Port Input / Unused Pins / Latch-up

3 Port Input / Unused Pins / Latch-up

How to connect Input Port Pins and how to proceed with unused Pins

It is strongly recommended to do not leave Input Pins unconnected. In this case those pins

can enter a so-called floating state. This can cause a high I

current, which is adverse to low

power modes. Also damage of the MCU can happen.

Use the internal pull-up/down resistors, if the port provides such function. If not, use external

pull-up or pull-down resistors to define the input-level. If both solutions are not possible, set

the Port Pin to Output.

Never connect a potential divider with almost same resistor values.

Be careful with connection of input pins to other devices, which can go into High-Z states.

Always use pull-up or pull-down resistors in this case.

Outputs from external circuits should always be connected via a serial resistor to a MCU input

pin.

Debouncing and decoupling capacitors should always be chosen as smallest as possible.

Please refer to chapter 3.2.

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MCU-AN-300033-E-V13

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