MC908GR16ACFA FREESCALE [Freescale Semiconductor, Inc], MC908GR16ACFA Datasheet - Page 65

• Manufacturer Part Number: MC908GR16ACFA
• Description: M68HC08 Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

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
4.4.4 PLL Analog Power Pin (V
V
potential as the V
4.4.5 PLL Analog Ground Pin (V
V
potential as the V
4.4.6 Oscillator Enable Signal (SIMOSCEN)
The SIMOSCEN signal comes from the system integration module (SIM) and enables the oscillator and
PLL.
4.4.7 Oscillator Enable in Stop Mode Bit (OSCENINSTOP)
OSCENINSTOP is a bit in the CONFIG2 register that enables the oscillator to continue operating during
stop mode. If this bit is set, the oscillator continues running during stop mode. If this bit is not set (default),
the oscillator is controlled by the SIMOSCEN signal which will disable the oscillator during stop mode.
4.4.8 Crystal Output Frequency Signal (CGMXCLK)
CGMXCLK is the crystal oscillator output signal. It runs at the full speed of the crystal (f
directly from the crystal oscillator circuit.
and OSC2 and may not represent the actual circuitry. The duty cycle of CGMXCLK is unknown and may
Freescale Semiconductor
DDA
SSA
is a ground pin used by the analog portions of the PLL. Connect the V
is a power pin used by the analog portions of the PLL. Connect the V
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.
Route V
capacitors as close as possible to the package.
Route V
capacitors as close as possible to the package.
DD
SS
pin.
pin.
DDA
SSA
carefully for maximum noise immunity and place bypass
Figure
carefully for maximum noise immunity and place bypass
4-2.)
MC68HC908GR16A Data Sheet, Rev. 1.0
DDA
SSA
Figure 4-2
)
)
NOTE
NOTE
NOTE
shows only the logical relation of CGMXCLK to OSC1
DDA
SSA
pin to the same voltage
pin to the same voltage
XCLK
) and comes
I/O Signals
65