1.5.4 Decode Output Truth Table
D3
D2
D1
D0
Conditions
0
0
0
0
No Signal
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
Call Progress Dual Tones:
Will detect 350+440, 400+450, 440+480 Hz tones
Non Call Progress Signal, e.g. Voice Activity
Call Progress Dual Tone including 620Hz Detection:
Will detect 480+620 Hz tones
Special Information Tone:
Will detect 950, 1400 and 1800 Hz tones
Call Progress Single Tone:
Will detect 400, 425, 440 and 450 Hz tones
Will detect a single tone lying outside the Call Progress
Band and within the Non Call Progress signal range
Call Progress Single Tone including 620Hz Detection:
Will detect 600 and 620 Hz tones
Fax/modem High Tone:
Will detect 2100 and 2200 Hz tones
Reserved for future use
Reserved for future use
Reserved for future use
Fax/modem Low Tone:
Will detect 1200 and 1300 Hz tones
Reserved for future use
Reserved for future use
Reserved for future use
1.6
Application Notes
1.6.1 General
Apply a reset after power-up by taking the ENABLE pin low. This places the device in a powersave mode and
resets the internal circuits. It also places the data word output (D0-D3) in a high impedance state, regardless
of the level on the CSN pin.
From this mode the device can be returned to normal operation without any additional settling time, when
using the component values recommended in Figure 2. The tone response times remain the same and are
given in section 1.7.1.
An interrupt is produced when the decode state is changed. This interrupt is reset by CSN going to logic "0".
When CSN is permanently at "0", the interrupt condition is a 5 µs logic "0" pulse on the IRQN pin. When CSN
is set to logic "1", the data word output (D0-D3) goes into a high impedance state.
ã 1999 Consumer Microcircuits Limited
9
D/663/3
CMLMICRO [ CML MICROCIRCUITS ]
