Fujitsu MB15C02 Datasheet page 15

Since the divide rations are unpredictable when the MB15C02 is turned on, it is necessary to initialize the divide
ratio for both dividers at power-on time. As shown in Figure 6, after setting the divide ratio for one of the dividers
(e.g., programmable reference divider), set LE to "H" level before setting the divide ratio for the other dividers (e.g.,
programmable divider). To change the divide ratio of one of the divider after initialization, input the serial data only
for that divider (the divide ratio for the other divider is preserved).
Data
Clock
LE
Serial data for program-
1*
mable reference divider
15 clocks
Figure 6. Inputting serial data(Setting divisors)
Serial data for program-
0*
mable divider
19 clocks
* : Control bit
MB15C02
15