TWR-56F8257 Freescale Semiconductor, TWR-56F8257 Datasheet - Page 38

• Manufacturer Part Number: TWR-56F8257
• Description: TOWER SYSTEM KIT MC56F8257
• Manufacturer: Freescale Semiconductor
• Type: DSC, Digital Signal Controllerr

Specifications of TWR-56F8257

• Contents: Board, Cables, Documentation, DVD
• For Use With/related Products: Freescale Tower System, MC56F8257
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

General System Control Information
when selecting a crystal, because crystal parameters determine the component values required to provide maximum stability
and reliable startup. The load capacitance values used in the oscillator circuit design should include all stray layout capacitances.
The crystal and associated components should be mounted as near as possible to the EXTAL and XTAL pins to minimize output
distortion and startup stabilization time. When using low-frequency, low-power mode, the only external component is the
crystal itself. In the other oscillator modes, load capacitors (C
resistor (R
5.4.3
The recommended method of connecting an external clock appears in
CLKIN pin while:
The external clock input must be generated using a relatively low-impedance driver with a maximum frequency not greater than
120 MHz.
38
•
•
both the EXT_SEL bit and the CLK_MODE bit in the OSCTL register are set, and
corresponding bits in the GPIOB_PER register in the GPIO module and the GPS_C0 bit in the GPS0 register in the
system integration module (SIM) are set to the correct values.
S
) may be used in high-gain modes. Recommended component values appear in
Figure 9. Typical Crystal Oscillator Circuit without Frequency Compensation Capacitor
Crystal Frequency = 4–16 MHz
OSC_DIV2 = 1 if 16 MHz is chosen
Alternate External Clock Input
Crystal Frequency = 4–16 MHz
OSC_DIV2 = 1 if 16 MHz is chosen
Figure 10. Typical Crystal or Ceramic Resonator Circuit
MC56F825x/MC56F824x Digital Signal Controller, Rev. 3
C
1
XTAL
XTAL
MC56F825x/MC56F824x
MC56F825x/MC56F824x
x
, C
y
) and feedback resistor (R
Figure
R
F
11. The external clock source is connected to the
EXTAL
EXTAL
C
2
F
Table
) are required. In addition, a series
27.
Freescale Semiconductor