MC68HC908MR8 Datasheet, PDF (123/372 Pages) Motorola, Inc – Microcontrollers

Clock Generator Module (CGM)
I/O Signals
SIMOSCEN
CGMXCLK
OSC1
R_B
X1
C1
OSC2
R_S*
C2
V_SS
CGMXFC
V_DDA
C_F
V_DD
C_BYP
*R_S can be 0 (shorted) when used with higher-frequency crystals.
Refer to manufacturer’s data.
Figure 8-3. CGM External Connections
8.5 I/O Signals
The following paragraphs describe the CGM input/output (I/O) signals.
8.5.1 Crystal Amplifier Input Pin (OSC1)
The OSC1 pin is an input to the crystal oscillator amplifier.
8.5.2 Crystal Amplifier Output Pin (OSC2)
The OSC2 pin is the output of the crystal oscillator inverting amplifier.
8.5.3 External Filter Capacitor Pin (CGMXFC)
The CGMXFC pin is required by the loop filter to filter out phase
corrections. A small external capacitor is connected to this pin.
NOTE:
To prevent noise problems, C_F should be placed as close to the
CGMXFC pin as possible, with minimum routing distances and no
routing of other signals across the C_F connection.
MC68HC908MR8 — Rev 4.1
Freescale Semiconductor
Clock Generator Module (CGM)
Technical Data
123