MC68HC705K1 Datasheet, PDF (22/140 Pages) Freescale Semiconductor, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
General Description
MCU
2 MΩ
CERAMIC
RESONATOR
V_SS
OSC1
OSC2
CER.
RES.
V_SS
C1 C2
V_DD
Figure 1-6. 3-Pin Ceramic Resonator Connections
To use the resonator-driven oscillator, the RC bit in the mask option
register must be clear. See 9.6 Mask Option Register. Clearing the RC
bit connects an internal 2-MΩ startup resistor between OSC1 and
OSC2.
1.6.2.3 2-Pin RC Oscillator
For maximum cost reduction, use the 2-pin RC oscillator configuration
shown in Figure 1-7. The OSC2 signal is a square wave, and the signal
on OSC1 is a triangular wave. The optimum frequency for the 2-pin
oscillator configuration is 2 MHz.
Technical Data
MCU
R
C3
OSC1
OSC2
V_SS
R C3
V_SS
C1 C2
V_DD
Figure 1-7. 2-Pin RC Oscillator Connections
To use the 2-pin RC oscillator configuration, the RC bit in the mask
option register must be programmed to a logic 1. Setting the RC bit
General Description
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MC68HC705K1 — Rev. 2.0