![](http://datasheet.mmic.net.cn/240000/5082-7623-BE200_datasheet_15638971/5082-7623-BE200_58.png)
TMS320LF2407A,TMS320LF2406A,TMS320LF2403A,TMS320LF2402A
TMS320LC2406A,TMS320LC2404A,TMS320LC2403A,TMS320LC2402A
DSP CONTROLLERS
SPRS145K
JULY 2000
REVISED AUGUST 2005
58
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251
1443
PLL-based clock module (continued)
XTAL2
XTAL1/CLKIN
PLL
XTAL
OSC
CLKOUT
F
in
3-bit
PLL Select
(SCSR1.[11:9])
R
1
C
1
C
2
PLLF
RESONATOR/
CRYSTAL
PLLF2
C
b1
C
b2
Figure 16. PLL Clock Module Block Diagram
Table 9. PLL Clock Selection Through Bits (11
9) in SCSR1 Register
CLK PS2
CLK PS1
CLK PS0
CLKOUT
4
×
F
in
2
×
F
in
1.33
×
F
in
1
×
F
in
0.8
×
F
in
0.66
×
F
in
0.57
×
F
in
0.5
×
F
in
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Default multiplication factor after reset is (1,1,1), i.e., 0.5
×
F
in
.
NOTE:
The bootloader sets the PLL to x2 or x4 option. If the bootloader is used, the value of CLKIN used
should not force CLKOUT to exceed the maximum rated device speed. See the “Boot ROM” section
for more details.
external reference crystal clock option
The internal oscillator is enabled by connecting a crystal across the XTAL1/CLKIN and XTAL2 pins as shown
in Figure 17a. The crystal should be in fundamental operation and parallel resonant, with an effective series
resistance of 30
150
and draws no more than 1 mW; it should be specified at a load capacitance of 20 pF.
NOTE: Lx240xA crystal biasing needs an external 1 M
resistor across X1 and X2 pins for reliable operation. See the
TMS320LF2407A,
LF2406A, LF2403A, LF2402A DSP Controllers Silicon Errata
(literature number SPRZ002) or the
TMS320LC2406A, TMS320LC2404A,
TMS320LC2402A DSP Controllers Silicon Errata
(literature number SPRZ185) for details on this requirement.
external reference oscillator clock option
The internal oscillator is disabled by connecting a clock signal to XTAL1/CLKIN and leaving the XTAL2 input
pin unconnected as shown in part b of Figure 17.