MC145740F 데이터 시트보기 (PDF) - Motorola => Freescale
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MC145740F Datasheet PDF : 12 Pages
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0
0
– 25
3.4 k 4 k
16 k
– 15 dB/OCT.
256 k
f (Hz)
– 55
Figure 1. Out–of–Band Energy
DTMF TONE CHANGED WITHOUT SILENT PERIOD
RxA
“A”
TD
“B”
“C”
(NOTE 1)
“D”
u u ton 1 10 mS
ton
toff
DV
(NOTE 2)
D0 – D3
“A”
(NOTE 3)
“B”
“C”
“D”
NOTES:
1. The high–to–low and low–to–high transition on the TD pin will appear immediately after the valid DTMF
tones are detected. The TD will also output a short H pulse when the device detects the DTMF tones
being changed without a silent period.
2. The high–to–low and low–to–high transition on the DV pin will appear after the programmed guard time
determined by two bits of serial data (CD1, CD0).
3. The device recognizes the DTMF tones changed without a silent period, and the four bits of data can
be read from the status register.
Figure 2. DTMF Detect Timing
NO DETECT
DETECT MINIMUM
WIDTH
ÎÎÎÎÎÎÎÎÎÎÎÎÎÎΖ3.5%ÎÎÎ –1.5%–2Hz
+ 1.5% + 2 Hz
LO
NO DETECT
ÎÎÎ+3.ÎÎÎ5% ÎÎÎÎÎÎÎÎÎ
Figure 3. DTMF Frequency Detect Band Width
MOTOROLA
MC145740
5
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