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About pull-up of unused pin processing

Last Updated:01/16/2018

Question:

Is an external pull-up resistor required for the unused pins configured as inputs if an on-chip pull-up resistor is connected (enabled in port settings)?

Answer:

When an on-chip pull-up resistor is enabled, the unused pins do not need to be externally pulled up. However, since the on-chip pull-up resistor is disabled until its settings are done by the user program after reset release, through-current may flow. To prevent this, the on-chip pull-up resistor must be enabled immediately after reset release.
Suitable Products
RL78/G13
RL78/G14
RL78/F12
RL78/F13
RL78/F14
RL78/F15
RL78/D1A
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