NEC PD17062 - Manual (Page 231)

231
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PD17062
18.6 PLL DISABLE MODE
The PLL frequency synthesizer is disabled when the CE pin is at a low level. It is also disabled when the
PLL reference mode select register (PLRFMODE, at address 13H) selects the PLL disable mode.
Table 18-1 summarizes how each block operates during the PLL disable mode.
Because the PLL reference mode select register is not initialized at a CE reset (its previous state is preserved),
it returns to the previous state after the CE pin goes low (selecting the PLL disable mode) then back to a high.
If it is necessary to select the PLL disable mode at a CE reset, the PLL reference mode select register should
be initialized by program.
The PLL frequency synthesizer is disabled at a power-on reset.
Table 18-1 Operation of Each Block During the PLL Disable Mode
Block CE pin = low or PLRFMODE = 1111B
VCO pin Pulled down internally
Programmable counter Frequency division disabled
Reference frequency generator Output disabled
Phase comparator Output disabled
Charge pump Error output pin floating