dsp56002fc80 Freescale Semiconductor, Inc, dsp56002fc80 Datasheet - Page 32

• Manufacturer Part Number: dsp56002fc80
• Description: 24-bit Digital Signal Processor
• Manufacturer: Freescale Semiconductor, Inc

Specifications
External Clock (EXTAL Pin)
EXTERNAL CLOCK (EXTAL PIN)
2-6
Note:
1. The suggested crystal source is
2. To reduce system cost, a ceramic
Suggested Component Values
R = 680 k
C = 20 pf
The DSP56002 system clock may be derived from the on-chip crystal oscillator as
shown in Figure 2-2, or it may be externally supplied. An externally supplied square
wave voltage source should be connected to EXTAL, leaving XTAL physically
unconnected to the board or socket. The rise and fall times of this external clock
should be 4 ns maximum.
ICM, # 433163 - 4.00
(4 MHz fundamental, 20 pf load) or
# 436163 - 30.00
(30 MHz fundamental, 20 pf load).
resonator may be used instead of
the crystal. Suggested source:
Murata-Erie #CST4.00MGW040
(4 MHz with built-in load
capacitors)
Fundamental Frequency
Crystal Oscillator
C
XTAL EXTAL
20%
XTAL1
10%
R
Figure 2-2 Crystal Oscillator Circuits
C
DSP56002/D, Rev. 3
Note:
1. *3
2. The suggested crystal source is ICM,
3. R2 limits crystal current.
4. Reference Benjamin Parzen, The Design
Suggested Component Values
R1 = 470 k
R2 = 330
C1 = 0.1 f
C2 = 26 pf
C3 = 20 pf
L1 = 2.37 H
XTAL = 40 MHz, AT cut, 20 pf load,
50
L1
# 471163 - 40.00 (40 MHz 3
20 pf load).
of Crystal and Other Harmonic
Oscillators, John Wiley & Sons, 1983.
EXTAL
rd
max series resistance
overtone crystal.
Crystal Oscillator
C1
C2
3rd Overtone
20%
10%
20%
10%
10%
XTAL1*
10%
R1
R2
C3
XTAL
MOTOROLA
rd
overtone,
AA0211