AN93
Rev. 1.4
43
Bit 15 represents the polarity of the Tip-Ring voltage, and a reversal of this bit represents a Tip-Ring polarity
reversal. LVS = 0x0000 if the Tip-Ring voltage is less than 3.0 V and, in the on-hook state, can be taken as “no line
connected.”
The ISOmodem reports the on-hook line voltage with the LVS bits in two’s complement. LVS has a full scale of 87 V
with an LSB of 1 V. The first code step (going from 0 to 1) is offset so that a 0 indicates a line voltage of less than
3 V. The accuracy of the LVS bits is ±10%. The user can read these bits directly through the LVS register. A typical
transfer function is shown in Figure 15.
When the ISOmodem is off-hook, the LCS bits measure loop current in 1.1 mA/bit resolution. These bits enable the
user to detect another phone going off-hook by monitoring the dc loop current. Line-current sensing is detailed in
Figure 16 and Table 41.
Figure 15. Typical Loop Voltage LVS Transfer Function
0
16
32
48
64
80
96
112
128
0
16
32
48
64
80
96
112
128
Tip/Ring V oltage (V olts )
LV
S
B
it
s
Summary of Contents for Si2404
Page 2: ...AN93 2 Rev 1 4 ...
Page 200: ...AN93 200 Rev 1 4 Figure 31 TAM Handset and Speakerphone Voice Paths ...
Page 201: ...AN93 Rev 1 4 201 Figure 32 Si3000 Codec Gain and Signal Selection Options ...
Page 290: ...AN93 290 Rev 1 4 Figure 57 256 Band Spectral Display Figure 58 2048 Band Spectral Display ...
Page 305: ...AN93 Rev 1 4 305 Figure 76 Parallel or SPI Port Interrupt Service Flowchart ...
