PXD20RM Datasheet, PDF (226/1628 Pages) Freescale Semiconductor, Inc – PXD20 Microcontroller

Clock
Monitor
Monitor_Failure
OSCCLK
Peak
Detector
Gain Control
V_{DDE_B} = 3.3 V
EXTAL
Rf
XTAL
Figure 8-26. FXOSC block diagram
8.4.1.5 External signal description
This section lists and describes the signals that connect off chip
8.4.1.5.1 V_{DDE_B} and V_SS — operating and ground voltage pins
Theses pins provides operating voltage (V_{DDE_B}) and ground (V_SS) for the FXOSC circuitry. This allows
the supply voltage to the FXOSC to use an independent bypass capacitor.
8.4.1.5.2 EXTAL and XTAL — input and output pins
These pins provide the interface for either a crystal or a 3.3 V CMOS compatible clock to control the
internal clock generator circuitry. EXTAL is the external clock input or the input to the crystal oscillator
amplifier. XTAL is the output of the crystal oscillator amplifier. The MCU internal system clock is derived
from the EXTAL input frequency. In full stop mode (PSTP = 0), the EXTAL pin is pulled down by an
internal resistor of typical 200 k.
8-30
PXD20 Microcontroller Reference Manual, Rev. 1
Preliminary—Subject to Change Without Notice
Freescale Semiconductor