13. Stabilization of power supply voltage
A sudden change in the supply voltage may cause the device to malfunction even within the specified VCC supply
voltage operating range. Therefore, the VCC supply voltage should be stabilized.
For the reference, stabilize the supply voltage by setting the following value.
•VCC ripple variations (peak-to-peak value) at commercial frequencies (50 Hz/60 Hz) fall below 10
% of the
standard VCC supply voltage
• The coefficient of fluctuation does not exceed 0.1 V/ms at instantaneous power switching.
In the device, there are internal registers which are initialized only by a power-on reset. To initialize these registers,
turn on the power again.
15. Port 0 to port 3 output during Power-on (External-bus mode)
As shown below, when power is turned on in External-Bus mode, in spite of reset input, there is a possibility that
output signal of Port 0 to Port 3 might be unstable.
16. Flash security Function
The security bit is located in the area of the flash memory.
If protection code 01H is written in the security bit, the flash memory is in the protected state by security.
Therefore please do not write 01H in this address if you do not use the security function.
Please refer to following table for the address of the security bit.
Flash memory size
Address for security bit
Embedded 1 Mbit Flash Memory
Port 0 to Port 3 outputs
might be unstable
Port 0 to Port 3 outputs = Hi-Z
Port 0 to Port 3