dsp56824 Freescale Semiconductor, Inc, dsp56824 Datasheet - Page 23

• Manufacturer Part Number: dsp56824
• Description: 16-bit Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

If the design uses an external clock circuit, apply the external clock input to the EXTAL input with the
XTAL pin left unconnected, as shown in Figure 7.
C
EXTAL XTAL
w
No.
1
2
3
4
5
6
7
8
9
Crystal Frequency = 32 kHz or 38.4 kHz
R
x
Clock cycle time
External clock input fall time
External clock input high time
Frequency of operation (external clock)
Instruction cycle time
External reference frequency
Crystal option,
External clock option,
External clock input rise time
External clock input low time
PLL output frequency
R
C
y
x
R
C
Example Crystal Parameters:
Motional capacitance, C
Motional inductance, L
Series resistance, R
Shunt capacitance, C
Load capacitance, C
(Assumes pin and trace
capacitance on the EXTAL and
XTAL pins is 9 pF each)
XCOLF = 0
x
w
= 10 M
Figure 6. Examples of Crystal Oscillator Circuits
= 12 pF
Figure 7. Connecting an External Clock Signal
XCOLF = 0
Freescale Semiconductor, Inc.
,
C
R
x
For More Information On This Product,
y
Table 22. Clock Operation Timing
= 19 pF
= 330 k
Characteristics
XCOLF = 1
S
L
0
= 36 k
= 12 pF
1
= 1 pF
1
= 7.47 kH
DSP56824 Technical Data
Go to: www.freescale.com
= 2.3 fF
External
EXTAL
Clock
DSP56824
Connected
C
EXTAL XTAL
XTAL
y
Not
R
z
Crystal Frequency = 2–10 MHz
C
z
R
C
Example Crystal Parameters:
Series resistance, R
Shunt capacitance, C
Load capacitance, C
(Assumes pin and trace
capacitance on the EXTAL and
XTAL pins is 9 pF each)
XCOLF = 1
z
y
, C
= 10 M
14.29
28.57
z
.032
Min
6.5
6.5
10
= 31 pF
—
—
0
0
External Clock Operation
70 MHz
S
L
Max
0
70
10
70
70
= 36 k
—
—
—
—
= 20 pF
3
3
= 7 pF
AA0180
AA1449
MHz
MHz
MHz
Unit
MHz
ns
ns
ns
ns
ns
ns
23