HD404618 Datasheet, PDF (65/89 Pages) Hitachi Semiconductor – 4-Bit Single-Chip Microcomputer

HD404618 Series
VT_ref
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
GND
Time slots
Figure 42 Waveform of Tone Output
Table 32 Frequency Deviation of the MCU from Standard DTMF Signals
Standard
DTMF (Hz)
MCU (Hz)
Deviation from
Standard (%)
R1
697
694.44
–0.37
R2
770
769.23
–0.10
R3
852
851.06
–0.11
R4
941
938.97
–0.22
C1
1,209
1,212.12
0.26
C2
1,336
1,333.33
–0.20
C3
1,477
1,481.48
0.30
C4
1,633
1,639.34
0.39
Note: This frequency deviation value does not include the frequency deviation due to the oscillator
element. Also note that in this case the ratio of the high level and low level widths in the oscillator
waveform due to the oscillator element will be 50% : 50%.
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