Specifications

AN93
Rev. 0.9 167
The Si3008 meets the DTMF and pulse dialing requirements for the countries in Table 105. Higher DTMF signal
levels than those required can be achieved.
Sufficiently high DTMF levels will clip due to the output signal level limitations of the Si3008. DTMF distortion
between 10–20% is generally acceptable.
Loop current limiting (previously required by CTR/TBR21 countries, such as France) is not supported by the
Si3008. Although current limiting is no longer required for certification, some customers require it for backward
compatibility.
Figure 35. Typical LCS Transfer Function
Table 107. Loop Current Sense Transfer Function
LCS[4:0] Condition
00000
b
– 00011
b
Insufficient line current for normal operation. Use the DODI bit
(Offset 0x34, bit 3) to determine if a line is still connected.
00100
b
– 11110
b
Normal operation.
11111
b
Loop current is excessive (>160 mA).
0
32
64
96
128
160
192
224
256
0 16 32 48 64 80 96 112 128 144
Loop Current (mA)
LCS Bits