SI2456-FT Datasheet, PDF (52/74 Pages) Silicon Laboratories – V.90, V.34, V.32BIS ISOMODEM® CHIPSET WITH INTEGRATED GLOBAL DAA

Si2456/33/14
U69 ITC3
Bit _{D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0}
Name
DIAL FJM VOL FLVM MODE
Type
R/W R/W R/W R/W R/W
Reset settings = 0x0006
Bit Name
Function
15:8 Reserved _{Read returns zero.}
7 Reserved _{Do not modify. Must be set to zero.}
6
DIAL DTMF Dialing Mode.
This bit should be set during DTMF dialing in CTR21 mode if LVCS < 12.
0 = Normal operation.
1 = Increase headroom for DTMF dialing.
5
FJM Force Japan DC Termination Mode.
0 = Normal Gain.
1 = When DCT = 2 (FCC mode), setting this bit forces Japan dc termination mode while allow-
ing for a transmit level of –1 dBm. See the “DTMF Dialing” section in “AN70: Si2456/Si2433/
Si2414/Si2403 Modem Designer’s Guide”.
4
VOL Line Voltage Adjust.
When set, this bit adjusts the TIP-RING line voltage. Lowering this voltage improves margin in
low-voltage countries. Raising this voltage may improve large-signal distortion performance.
0 = Normal operation.
1 = Lower DCT voltage.
3
FLVM Force Low Voltage Mode.
When DCT (U67, bits 3:2) = 10 (FCC mode), setting FLVM forces the low voltage mode (see
DCT = 00) while allowing for a transmit level of –1 dBm.
0 = Disable.
1 = Enable.
2 MODE Mode.
This bit enables on-hook line monitoring. It is automatically set while on-hook and cleared
while off-hook.
1:0 Reserved Do not modify.
52
Rev. 1.2