MC68HC05V12 Datasheet, PDF (29/246 Pages) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

Freescale Semiconductor, Inc.
General Description
Functional Pin Descriptions
1.6.5 OSC1 and OSC2
The OSC1 and OSC2 pins are the connections for the on-chip oscillator.
OSC1 is the input to the oscillator inverter. The output (OSC2) will
always reflect OSC1 inverted except when the device is in stop mode
which forces OSC2 high.
The OSC1 and OCS2 pins can accept these sets of components:
1. A crystal as shown in Figure 1-3(a)
2. A ceramic resonator as shown in Figure 1-3(a)
3. An external clock signal as shown in Figure 1-3(b)
The frequency, f_OSC, of the oscillator or external clock source is divided
by two to produce the internal operating frequency, f_OP.
MCU
MCU
OSC1
OSC2
10 MΩ*
20 pF *
4 MHz*
20 pF *
OSC1
OSC2
UNCONNECTED
EXTERNAL CLOCK
(a) Crystal or Ceramic
Resonator Connections
(b) External Clock
Source Connection
*Values shown are typical. For further information, consult the crystal oscillator vendor.
Figure 1-3. Oscillator Connections
1.6.5.1 Crystal Oscillator
The circuit in Figure 1-3(a) shows a typical oscillator circuit for an AT-
cut, parallel resonant crystal.
NOTE:
The crystal manufacturer’s recommendations should be followed, as the
crystal parameters determine the external component values required to
provide maximum stability and reliable startup.
MC68HC05V12 — Rev. 2.0
General Description
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Technical Data