MB90420G/425G Series
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5.
Real Time Clock Timer
The real time clock timer is composed of a real time clock timer control register, sub second data register, second/
minute/hour data registers, 1/2 clock divider, 21-bit prescaler and second/minute/hour counters. Because the
MCU oscillation frequency operates on a given real time clock timer operation, a 4 MHz frequency is assumed.
The real time clock timer operates as a real world timer and provides real world time information.
Block diagram
INTE0 INT0
EN
CI
EN
LOAD
CO
OE
WOT
IRQ#30
CO
INTE1
ST
UPDT
INT1
INTE2 INT2
INT3
Main oscillator clock
1/2 clock
divider
21-bit
prescaler
Sub second
register
Second
counter
Minute
counter
Hour
counter
6-bit
5-bit
Second/minute/hour register