Unused pins are configured as follows typically:
- Input-dedicated pin: Fixed (pull-up, pull-down, connected to the power supply or ground)
- Output-dedicated pin: Open
- I/O pin: Fixed to input (pull-up or pull-down), or left open to output
- NC pin: Connection is not allowed
When the input pin does not install a resistor to connect with the power supply directly or ground, the pin may be affected by the spike noise on the power supply line, and may cause malfunction.
Or, when an unexpected accident occurs to damage the CPU input protection circuit, a large current flows through the CPU which may damage the CPU terminally. So, we recommend installing a pull-up resistor or pull-down resistor with the unused input pin (or I/O pin which is set to input).
Install the pull-up or pull-down resistors between 4.7 kΩ to 100 kΩ.
As the pins with weak keeper has limitations on the resistor value, refer to the manual of the MCU. Configuration of some are specified by Renesas. Make sure to refer the Hardware Manual of the MCU.
When leaving the input-dedicated pin or I/O pins (default: input port) open, it is possible that the pin floats to the midpoint voltage would cause the through current in the MCU internally. A through current may degrade or damage the pins.
|SH7131, SH7132, SH7136, SH7137|
|SH7083, SH7084, SH7085, SH7086|
|SH7052, SH7053, SH7054|
|SH7047, SH7049, SH7105, SH7107, SH7109|
|SH7046, SH7148, SH7101, SH7048, SH7104, SH7106, SH7108|
|SH7040, SH7041, SH7042, SH7043, SH7044, SH7045|
|SH7032, SH7034, SH7034B|
|SH7014, SH7016, SH7017|