MC908JB16DWE Datasheet, PDF (94/332 Pages) Freescale Semiconductor, Inc – Microcontrollers

Oscillator (OSC)
7.3 Oscillator External Connections
In its typical configuration, the oscillator requires five external
components. The crystal oscillator is normally connected in a Pierce
oscillator configuration, as shown in Figure 7-1. This figure shows only
the logical representation of the internal components and may not
represent actual circuitry. The oscillator configuration uses five
components:
• Crystal, X₁ (nominally 12MHz)
• Fixed capacitor, C₁
• Tuning capacitor, C₂ (can also be a fixed capacitor)
• Feedback resistor, R_B
• Series resistor, R_S (not required for 12MHz)
FROM SIM
TO CGM
TO COP, SCI
TO SIM
SIMOSCEN
MCU
OSCXCLK
CLOCK OSCDCLK
DOUBLER
÷2 ^OSCOUT
OSC1
R_B
÷2
OSC2
TO USB
Technical Data
94
X1
C1 ^{12 MHz}
R_S*
* R_S can be 0 (shorted) when used with
C2
higher frequency crystals.
Refer to manufacturer’s data.
Figure 7-1. Oscillator External Connections
The series resistor (R_S) is included in the diagram to follow strict Pierce
oscillator guidelines and may not be required for all ranges of operation,
especially with high-frequency crystals. Refer to the crystal
manufacturer’s data for more information.
Oscillator (OSC)
MC68HC908JB16 — Rev. 1.1
Freescale Semiconductor