ADSP-214xx SHARC Processor Hardware Reference
22-3
Power Management
multiplication range, the processor uses a combination of programmable
multipliers in the PLL feedback circuit and output configuration blocks.
The processor uses an on-chip, phase-locked loop (PLL) to generate its
internal clock, which is a multiple of the
CLKIN
frequency. The PLL
requires some time to achieve phase lock and
CLKIN
must be valid for a
minimum time period during reset before the
RESET
signal can be deas-
serted. For information on minimum clock setup, external crystal use, and
range for any given
CLKIN
frequency, see the appropriate product data
sheet.
A detailed diagram along with specific equations on the derivation
of VCO frequency with reference to
CLKIN
can be found in the
appropriate product data sheet.
PLL Input Clock
If an external clock oscillator is used, it should NOT drive the
CLKIN
pin
when the processor is not powered. The clock must be driven immediately
after power-up; otherwise, internal gates stay in an undefined (hot) state
and can draw excess current. After power-up, allow sufficient time for the
oscillator to start up, reach full amplitude, and deliver a stable
CLKIN
signal
to the processor before the reset is released. This may take several millisec-
onds and depends on the choice of crystal, operating frequency, loop gain
and capacitor ratios. For details on timing, refer to the appropriate prod-
uct data sheet.
Pre-Divider Input
This unit divides the PLL input clock by 2 if enabled (using the
INDIV
bit). The pre-divider input is part of the PLL loop, therefore, if a program
changes the PLL input clock (affecting the VCO frequency), the PLL
must be put in bypass mode before the change is made. This is described
in
.
www.BDTIC.com/ADI
Содержание SHARC ADSP-214 Series
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Страница 72: ...Notation Conventions lxxii ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 130: ...Programming Model 2 52 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 264: ...Programming Models 3 134 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 290: ...Programming Model 4 26 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 296: ...Programming Model 5 6 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 396: ...Effect Latency 7 28 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 520: ...Programming Model 10 62 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 656: ...Programming Model 15 40 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 714: ...Programming Model 19 10 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...