SI3220-KQ Silicon Laboratories Inc, SI3220-KQ Datasheet - Page 59

• Manufacturer Part Number: SI3220-KQ
• Description: IC SLIC/CODEC DUAL-CH 64TQFP
• Manufacturer: Silicon Laboratories Inc
• Series: ProSLIC®r

Specifications of SI3220-KQ

• Package / Case: *
• Function: Subscriber Line Interface Concept (SLIC), CODEC
• Interface: GCI, PCM, SPI
• Number Of Circuits: 2
• Voltage - Supply: 3.3V, 5V
• Current - Supply: 65mA
• Power (watts): 941mW
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Includes: Battery Switching, BORSCHT Functions, DTMF Generation and Decoding, FSK Tone Generation, Modem and Fax Tone Detection
• Product: Telecom
• Supply Voltage (min): 3.13 V
• Supply Current: 22 mA
• Maximum Operating Temperature: + 70 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Number Of Channels: 2
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

DTMF Detection
On-chip DTMF detection, also known as Touch Tone, is
available in the Si3220 and Si3225.
It is an in-band signaling system that replaces the pulse-
dial signaling standard. In DTMF, two tones generate a
DTMF digit. One tone is chosen from the four possible
row tones and one tone is chosen from the four possible
column tones. The sum of these tones constitute one of
16 possible DTMF digits. The row and column tones
and corresponding digits are shown in Table 35.
DTMF detection is performed using a modified Goertzel
algorithm to compute the DFT for each of the eight
DTMF frequencies and their second harmonics. At the
end of the DFT computation, the squared magnitudes of
the DFT results for the 8 DTMF fundamental tones are
computed. The row results are sorted to determine the
strongest row frequency, and the column frequencies
are sorted as well. At the completion of this process,
checks are made to determine if the strongest row and
column tones constitute a DTMF digit.
The detection process occurs twice within the 45 ms
minimum tone time. A digit must be detected on two
consecutive tests after a pause to be recognized as a
new digit. If all tests pass, an interrupt is generated and
the DTMF digit value is loaded into the DTMF register
according to the following table. If tones occur at the
maximum rate of 100 ms per digit, the interrupt must be
serviced within 85 ms so that the current digit is not
I
BUF
Z
A
Figure 38. Pulse Metering Generation Block Diagram
+
+
Metering
Pulse
DAC
ADC
DAC
Preliminary Rev. 0.91
Oscillator
Metering
Pulse
x
+
Decimation
Filter
overwritten by a new one. There is no buffering of the
digit information.
Table 36 outlines the hex code corresponding to the
detected DTMF digits.
697 Hz
770 Hz
852 Hz
941 Hz
Volume
8 kHz
Table 35. DTMF Row/Column Tones
1209 Hz
1
4
7
*
PMRAMP
Logic
7FFF
Clip
or 0
±
+
Peak Detector
1336 Hz
Si3220/Si3225
2
5
8
0
12/16 kHz
Bandpass
–
1477 Hz
+
3
6
9
#
PMAMPTH
1633 Hz
C
D
A
B
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