Texas Instruments TMS320C6727 Manuale Utente
www.ti.com
BOARD
DV
DD
(3.3 V)
EMI
Filter
10
m
F
0.1
m
F
PLLHV
Place Filter and Capacitors as Close
to DSP as Possible
EMI Filter: TDK ACF451832−333, −223, −153, or −103,
Panasonic EXCCET103U, or Equivalent
+
TMS320C6727, TMS320C6726, TMS320C6722
Floating-Point Digital Signal Processors
SPRS268E – MAY 2005 – REVISED JANUARY 2007
Table 4-40. Allowed PLL Operating Conditions
ALLOWED SETTING OR RANGE
PARAMETER
DEFAULT VALUE
MIN
MAX
1
PLLRST = 1 assertion time during initialization
N/A
125 ns
2
Lock time before setting PLLEN = 1. After changing D0, PLLM, or
N/A
187.5 µs
input clock.
3
PLL input frequency (PLLREF after D0
(1)
)
12 MHz
50 MHz
4
PLL multiplier values (PLLM)
x13
x4
x25
5
PLL output frequency (PLLOUT before dividers D1, D2, D3)
(2)
N/A
140 MHz
600 MHz
6
SYSCLK1 frequency (set by PLLM and dividers D0, D1)
PLLOUT/1
Device Frequency
Specification
7
SYSCLK2 frequency (set by PLLM and dividers D0, D2)
PLLOUT/2
/2, /3, or /4 of SYSCLK1
8
SYSCLK3 frequency (set by PLLM and dividers D0, D3)
PLLOUT/3
EMIF Frequency
Specification
(1)
Some values for the D0 divider produce results outside of this range and should not be selected.
(2)
In general, selecting the PLL output clock rate closest to the maximum frequency will decrease clock jitter.
CAUTION
SYSCLK1, SYSCLK2, SYSCLK3 must be configured as aligned by setting ALNCTL[2:0]
to '1'; and the PLLCMD.GOSET bit must be written every time the dividers D1, D2, and
D3 are changed in order to make sure the change takes effect and preserves
alignment.
to '1'; and the PLLCMD.GOSET bit must be written every time the dividers D1, D2, and
D3 are changed in order to make sure the change takes effect and preserves
alignment.
CAUTION
When changing the PLL parameters which affect the SYSCLK1, SYSCLK2, SYSCLK3
dividers, the bridge BR2 in
dividers, the bridge BR2 in
must be reset by the CFGBRIDGE register. See
.
The PLL is an analog circuit and is sensitive to power supply noise. Therefore it has a dedicated 3.3-V
power pin (PLLHV) that should be connected to DV
power pin (PLLHV) that should be connected to DV
DD
at the board level through an external filter, as
illustrated in
Figure 4-44. PLL Power Supply Filter
Peripheral and Electrical Specifications
103