SI2457-D-FS Silicon Laboratories Inc, SI2457-D-FS Datasheet - Page 109

• Manufacturer Part Number: SI2457-D-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2457-D-FS

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

15:14 Reserved Read returns zero.
13:12 MINI[1:0] Minimum Operational Loop Current.
11:10 Reserved Read returns zero
15:7
5:0
Bit
Bit
5:4
3:2
6
9
8
7
6
1
Reserved Read returns zero.
Reserved Read returns zero.
DCV[1:0] Tip-Ring Voltage Adjust.
Reserved Read returns zero.
Reserved Read returns zero.
Name
Name
DCR
OHS
ILIM
FDT
RZ
Adjusts the minimum loop current at which the DAA can operate. Increasing the minimum oper-
ational loop current can improve signal headroom at lower Tip-Ring voltages.
Current Limiting Enable.
0 = Current limiting mode disabled.
1 = Current limiting mode enabled. This mode limits loop current to a maximum of 60 mA per
the legacy TBR21 standard.
DC Impedance Selection.
0 = 50  dc termination slope is selected. This mode should be used for all standard
applications.
1 = 800  dc termination is selected.
On-Hook Speed.
See OHS2.
These bits adjust the voltage on the DCT pin of the line-side device, which affects the Tip-Ring
voltage on the line. Low-voltage countries should use a lower Tip-Ring voltage. Raising the Tip-
Ring voltage can improve signal headroom.
Ringer Impedance.
0 = Maximum (high) ringer impedance.
1 = Synthesize ringer impedance. C15, R14, Z2, and Z3 must not be installed when setting this
bit.
MINI[1:0]
DCV[1:0]
Function
Frame Detect.
0 = ISOcap frame lock not established
1 = ISOcap frame lock established
00
01
10
11
00
01
10
11
Min Loop Current
DCT Pin Voltage
3.1 V
3.2 V
3.35 V
3.5 V
10 mA
12 mA
14 mA
16 mA
Table 67. U67 Bit Map*
Table 66. U66 Bit Map
Rev. 1.3
Function
AN93
109