MC68HC908GR8A_07 Datasheet, PDF (63/260 Pages) Freescale Semiconductor, Inc – Microcontrollers

SIMOSCEN
OSCSTOPENB
(FROM CONFIG)
OSC1
RB
X1
C1
CGMXCLK
OSC2
CGMXFC
RS
R_F1
C_F2
C_F1
C2
I/O Signals
V_SSA
V_DDA
V_DD
CBYP
0.1 μF
Note: Filter network in box can be replaced with C_F but will degrade stability.
Figure 4-2. CGM External Connections
4.4 I/O Signals
The following paragraphs describe the CGM I/O signals.
4.4.1 Crystal Amplifier Input Pin (OSC1)
The OSC1 pin is an input to the crystal oscillator amplifier.
4.4.2 Crystal Amplifier Output Pin (OSC2)
The OSC2 pin is the output of the crystal oscillator inverting amplifier.
4.4.3 External Filter Capacitor Pin (CGMXFC)
The CGMXFC pin is required by the loop filter to filter out phase corrections. An external filter network is
connected to this pin. (See Figure 4-2.)
NOTE
To prevent noise problems, the filter network should be placed as close to
the CGMXFC pin as possible, with minimum routing distances and no
routing of other signals across the network.
MC68HC908GR8A • MC68HC908GR4A Data Sheet, Rev. 5
Freescale Semiconductor
63