Datasheet

Oscillator (OSC)
Technical Data MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
90 Oscillator (OSC) Freescale Semiconductor
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, X
1
• Fixed capacitor, C
1
• Tuning capacitor, C
2
(can also be a fixed capacitor)
• Feedback resistor, R
B
• Series resistor, R
S
(optional)
Figure 7-1. Oscillator External Connections
C1 C2
SIMOSCEN
OSCXCLK
X1
R
S
*
* R
S
can be 0 (shorted) when used with
MCU
FROM SIM
OSCOUT
TO USB TO SIM
CLOCK
DOUBLER
÷ 2
TO SIM
OSC1 OSC2
R
B
higher frequency crystals.
Refer to manufacturer’s data.