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July 16, 1999
GENERAL RELEASE SPECIFICATION
MC68HC05J5A
REV 2.1
MOTOROLA
C-1
APPENDIX C
MC68HRC705J5A
This appendix describes the MC68HRC705J5A, the emulation part for
MC68HRC05J5A, and a resistor-capacitor (RC) oscillator mask option version of
the MC68HC705J5A. The entire MC68HC05J5A data sheet and appendix B
applies to the MC68HRC705J5A, with exceptions outlined in this appendix.
C.1
INTRODUCTION
The MC68HRC705J5A is a resistor-capacitor (RC) oscillator mask option version
of the MC68HC705J5A (see
Appendix B
). The MC68HRC705J5A is functionally
identical to the MC68HC705J5A with the exception that the MC68HRC705J5A
supports the RC oscillator only, as outlined in
Appendix C.2
.
The MC68HRC705J5A is not available in the 16-pin SOIC package.
C.2
RC OSCILLATOR CONNECTIONS
This is the only oscillator option supported by the MC68HRC705J5A device.
On the MC68HRC705J5A device, an external resistor is connected between
OSC2/R pin and the V
SS
pin as shown in
Figure C-1
. The typical operating fre-
quency f
OSC
is set at 4MHz with the external R tied to V
SS
. Use the graph in
Figure C-2
to select the value of R for the required oscillator frequency.
The tolerance of this RC oscillator is guaranteed to be no greater than
±
15% at
the specified conditions of 0
°
C to 40
°
C and 5V
±
10% V
DD
providing that the toler-
ance of the external resistor R is at most
±
1% and the center frequency range is
from 3.8MHz to 4.2MHz. The center frequency is the nominal operating frequency
of the RC oscillator and can be adjusted by adjusting the external R value to
change the internal VCO charging current.
In order to obtain an oscillator clock with the best possible tolerance, the external
resistor connected to the OSC2/R pin should be grounded as close to the VSS pin
as possible and the other terminal of this external resistor should be connected as
close to the OSC2/R pin as possible.
Figure C-1. RC Oscillator Connections
MCU
OSC2/R
OSC1
R
F
Freescale Semiconductor, Inc.
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Go to: www.freescale.com
n
.