![](http://datasheet.mmic.net.cn/240000/5082-7623-BE200_datasheet_15638971/5082-7623-BE200_59.png)
TMS320LF2407A,TMS320LF2406A,TMS320LF2403A,TMS320LF2402A
TMS320LC2406A,TMS320LC2404A,TMS320LC2403A,TMS320LC2402A
DSP CONTROLLERS
SPRS145K
JULY 2000
REVISED AUGUST 2005
59
POST OFFICE BOX 1443
HOUSTON, TEXAS 77251
1443
external reference oscillator clock option (continued)
External Clock Signal
(Toggling 0
3.3 V)
C
b1
(see Note A)
XTAL2
XTAL1/CLKIN
XTAL1/CLKIN
XTAL2
Crystal
C
b2
(see Note A)
(a)
(b)
NC
NOTE A: TI recommends that customers have the resonator/crystal vendor characterize the operation of their device with the DSP chip. The
resonator/crystal vendor has the equipment and expertise to tune the tank circuit. The vendor can also advise the customer regarding
the proper tank component values that will ensure start-up and stability over the entire operating range.
Figure 17. Recommended Crystal/Clock Connection
loop filter
The PLL module uses an external loop filter circuit for jitter minimization. The components for the loop filter
circuit are R1, C1, and C2. The capacitors (C1 and C2) must be non-polarized. This loop filter circuit is connected
between the PLLF and PLLF2 pins (see Figure 16). For examples of component values of R1, C1, and C2 at
a specified oscillator frequency (XTAL1), see Table 10.
Table 10. Loop Filter Component Values With Damping Factor = 2.0
XTAL1/CLKIN FREQUENCY
(MHz)
R1 (
) (
±
5% TOLERANCE)
C1 (
μ
F) (
±
20% TOLERANCE)
C2 (
μ
F) (
±
20% TOLERANCE)
4
4.7
3.9
0.082
5
5.6
2.7
0.056
6
6.8
1.8
0.039
7
8.2
1.5
0.033
8
9.1
1
0.022
9
10
0.82
0.015
10
11
0.68
0.015
11
12
0.56
0.012
12
13
0.47
0.01
13
15
0.39
0.0082
14
15
0.33
0.0068
15
16
0.33
0.0068
16
18
0.27
0.0056
17
18
0.22
0.0047
18
20
0.22
0.0047
19
22
0.18
0.0039
20
24
0.15
0.0033
low-power modes
The 240xA has an IDLE instruction. When executed, the IDLE instruction stops the clocks to all circuits in the
CPU, but the clock output from the CPU continues to run. With this instruction, the CPU clocks can be shut down
to save power while the peripherals (clocked with CLKOUT) continue to run. The CPU exits the IDLE state if
it is reset, or, if it receives an interrupt request.