HT9020B View Datasheet(PDF) - Holtek Semiconductor
Part Name
Description
Manufacturer
HT9020B Datasheet PDF : 12 Pages
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HT9020
Functional Description
Decoder
The HT9020 call progress tone decoder (DEC/ABRC=VDD) can be used in the U.S.A. and many other
countries in the world. The signal format, truth table and timing of the decoder are shown below.
The signal format of the call progress tone
Tone
Frequency
Precision Dial Tone
350Hz + 440Hz
Old Dial Tone
120Hz(or 133Hz, ..) + 600Hz
Precision Busy Tone
480Hz + 620Hz
Old Busy Tone
120Hz + 600Hz
Precision Reorder Tone 480Hz + 620Hz
Old Reorder Tone
120Hz + 600Hz
Precision Ring-back Tone 440Hz + 480Hz
Old Ring-back Tone
40Hz (or the others) + 420Hz
Condition
Continuous
Continuous
0.5sec On and 0.5sec Off
0.5sec On and 0.5sec Off
0.3sec On and 0.2sec Off
0.2sec On and 0.3sec Off or 0.25sec
On and 0.25sec Off
2sec On and 4sec Off
2sec On and 4sec Off
The truth table of the decoder
Tone
Transition No. DIAL RBK BUSY
DV
OE/HKOFF
Initial
—
0
0
0
0
0
Dial
1
1
0
0
1
0
Ringback
2~4
0
1
0
1
0
Busy/Reorder
5~16
0
0
1
1
0
Overflow
over 16
0
0
0
1
0
Output Disable
—
Hi-Z
Hi-Z
Hi-Z
*
1
Notes: Hi-Z: Hi impedance
*: previous state
7
21st Aug ’98
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