Specifications

Si2457/Si2434/Si2415
Rev. 0.91 59
Reset settings = 0x0000
U79 GEN4
Bit D15D14D13D12D11D10D9 D8 D7D6D5D4D3D2D1D0
Name LVCS[4:0]
Type R
Bit Name Function
15:5 Reserved
Read returns zero.
4:0 LVCS[4:0] Line Voltage Current Sense.
Represents either the line voltage, loop current, or on-hook line monitor.
On-Hook Voltage Monitor (2.75 V/bit ±20%).
00000 = No line connected.
00001 = Minimum line voltage (V
MIN
=3.0V ± 0.5V).
11111 = Maximum line voltage (87 V ± 20%).
The line voltage monitor full scale may be modified by changing R5 as follows:
V
MAX
=V
MIN
+ 4.2 (10M + R5 + 1.6k)/(R5 +1.6k)/5
Off-Hook Loop Current Monitor (3 mA/bit).
00000 = No loop current.
00001 = Minimum loop current.
11110 = Maximum loop current.
11111 = Loop current is excessive (overload).
Overload > 140 mA in all modes except TBR21
Overload > 54 mA in TBR21 mode
LVCS is backward compatible with Si2456/33/14 ISOmodems. The LVCS value is absolute
and does not reflect loop polarity. See U6C (LVS)[15:8] for 1 V/bit resolution and signed twos
complement output