MB90540/540G/545/545G Series
(12) Indeterminate outputs from ports 0 and 1 (MB90F543/F549/V540/V540G only)
During oscillation setting time of step-down circuit (during a power-on reset) after the power is turned on, the
outputs from ports 0 and 1 become following state.
• If RST pin is “H”, the outputs become indeterminate.
• If RST pin is “L”, the outputs become high-impedance.
Pay attention to the port output timing shown as follow.
• RST pin is “H”
Oscillation setting time*2
Power-on reset*1
VCC (Power-supply pin)
PONR (power-on reset) signal
RST (external asynchronous reset) signal
RST (internal reset) signal
Oscillation clock signal
KA (internal operation clock A) signal
KB (internal operation clock B) signal
PORT (port output) signal
Period of indeterminated
*1 : Power-on reset time : Period of “clock frequency × 217” (Clock frequency of 16 MHz : 8.19 ms)
*2 : Oscillation setting time : Period of “clock frequency × 218” (Clock frequency of 16 MHz : 16.38 ms)
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