mc68hc908qf4 Freescale Semiconductor, Inc, mc68hc908qf4 Datasheet - Page 95

• Manufacturer Part Number: mc68hc908qf4
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

11.3.4 RC Oscillator
11.4 Oscillator Module Signals
11.4.1 Crystal Amplifier Input Pin (OSC1)
MC68HC908QF4 — Rev. 1.0
MOTOROLA
The RC oscillator circuit is designed for use with external R to provide a clock
source with tolerance less than 25%.
In its typical configuration, the RC oscillator requires two external components, one
R and one C. In the MC68HLC908QF4, the capacitor is internal to the chip. The R
value should have a tolerance of 1% or less, to obtain a clock source with less than
25% tolerance. The oscillator configuration uses one component, R
In this configuration, the OSC2 pin can be left in the reset state as PTA4. Or, the
OSC2EN bit in the port A pullup enable register can be set to enable the OSC2
output function on the pin. Enabling the OSC2 output slightly increases the external
RC oscillator frequency, f
The following paragraphs describe the signals that are inputs to and outputs from
the oscillator module.
The OSC1 pin is either an input to the crystal oscillator amplifier, an input to the RC
oscillator circuit, or an external clock source.
FROM SIM
Freescale Semiconductor, Inc.
MCU
SIMOSCEN
For More Information On This Product,
V
DD
Figure 11-3. RC Oscillator External Connections
EN
Go to: www.freescale.com
R
EXT
Oscillator Module (OSC)
EXTERNAL RC
OSC1
OSCILLATOR
RCCLK
.
INTCLK
RCCLK
PTA4/BUSCLKX4 (OSC2)
See
for component value requirements.
Section 17. Electrical Specifications
0
1
1
0
OSCRCOPT
TO SIM
PTA4
BUSCLKX4
I/O
Oscillator Module Signals
Oscillator Module (OSC)
÷ 2
TO SIM
EXT
BUSCLKX2
.
PTA4
OSC2EN
Data Sheet
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