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CHAPTER 13 PLL FREQUENCY SYNTHESIZER
User’s Manual U15104EJ2V0UD
After setting the above PLL data registers (PLLR and PLLR0), data must be transferred to the
programmable counter and swallow counter by setting bit 0 (PLLNS0) of the PLL data transfer register
(PLLNS).
In this example, a value of half the N value is set to the higher 16 bits of the PLL data register (PLLR)
by shifting the N value resulting from calculation 1 bit to the right.
If the N value is calculated as follows with the least significant bit of the N value in PLLSCN fixed to 0,
the result of the calculation (N
PLLR
) can be set to the PLL data register (PLLR) as is.
If the calculation result is set in this way, however, the input frequency (f
VCOH
) is 2
×
f
r
(reference frequency)
of the set value N
PLLR
.
N
PLLR
=
f
VCOH
2f
r
Содержание mPD178053
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