
80C196KB USER’S GUIDE
6.1 Analog Outputs
Analog outputs can be generated by two methods, ei-
ther by using the PWM output or the HSO. See Section
9.7 for information on generating a PWM with the
High Speed Output Unit. Either device will generate a
rectangular pulse train that varies in duty cycle and
period. If a smooth analog signal is desired as an out-
put, the rectangular waveform must be filtered.
In most cases this filtering is best done after the signal
is buffered to make it swing from 0 to 5 volts since both
of the outputs are guaranteed only to low current lev-
els. A block diagram of the type of circuit needed is
shown in Figure 6-4. By proper selection of compo-
nents, accounting for temperature and power supply
drift, a highly accurate 8-bit D to A converter can be
made using either the HSO or the PWM output. Figure
6-5 shows two typical circuits. If the HSO is used the
accuracy could be theoretically extended to 16-bits,
however the temperature and noise related problems
would be extremely hard to handle.
When driving some circuits it may be desirable to use
unfiltered Pulse Width Modulation. This is particularly
true for motor drive circuits. The PWM output can
generate these waveforms if a fixed period on the order
of 64
m
s is acceptable. If this is not the case then the
HSO unit can be used. The HSO can generate a vari-
able waveform with a duty cycle variable in up to 65536
steps and a period of up to 87.5 milliseconds. Both of
these outputs produce CHMOS levels.
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Figure 6-4. D/A Buffer Block Diagram
270651 – 15
270651 – 16
Figure 6-5. Buffer Circuits for D/A
35
数控原理与维修
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Содержание 80C196KB Series
Страница 1: ...November 1990 80C196KB User s Guide Order Number 270651 003 http www agreenleaf cn...
Страница 59: ...80C196KB USER S GUIDE Figure 11 7 Ideal A D Characteristic 270651 37 55 http www agreenleaf cn...
Страница 60: ...80C196KB USER S GUIDE Figure 11 8 Actual and Ideal Characteristics 270651 38 56 http www agreenleaf cn...
Страница 61: ...80C196KB USER S GUIDE Figure 11 9 Terminal Based Characteristic 270651 39 57 http www agreenleaf cn...
Страница 70: ...80C196KB USER S GUIDE Figure 13 5 Reset Sequence 80C196KB Reset Sequence 270651 45 66 http www agreenleaf cn...
Страница 83: ...80C196KB USER S GUIDE 270651 80 Figure 15 14 AC Timing Diagrams 79 http www agreenleaf cn...
Страница 84: ...80C196KB USER S GUIDE 270651 81 270651 84 Figure 15 14 AC Timing Diagrams Continued 80 http www agreenleaf cn...