SI2493-C-FS Silicon Laboratories Inc, SI2493-C-FS Datasheet - Page 87

• Manufacturer Part Number: SI2493-C-FS
• Description: IC ISOMODEM SYSTEM-SIDE 16SOIC
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FS

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: UART
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

When DCR = 1
impedance of 800 Ω, which can be used to enhance
operation with a parallel phone, for improved low line
voltage performance, and for overload. This bit must be
set to 0 when the modem is on-hook. See "3.5.20.4. DC
Termination" on page 141 for details.
Bit 6 (OHS) is used to control the speed with which the
modem drops the line. The default setting, OHS = 0
causes the modem to go from the off-hook state
(drawing loop current) to the on-hook state (not drawing
loop current) quickly.
This operation is acceptable in many countries.
However, some countries, such as Italy, South Africa,
and Australia, have spark quenching requirements.
Spark quenching can be accomplished by placing a
resistor and a capacitor across the hookswitch or by
controlling the off-hook to on-hook transition speed to
prevent excessive voltage buildup. Slowly reducing the
loop current to zero fulfills the spark quenching
requirement without the extra components. Setting
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
6
9
8
Reserved Read returns zero.
Reserved Read returns zero.
Reserved Read returns zero.
Name
Name
ILIM
FDT
b
, the device presents a dc line
Adjusts the minimum loop current at which the DAA can operate. Increasing the minimum oper-
ational loop current can improve signal headroom at a lower TIP/RING voltage.
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 CTR21 standard.
MINI[1:0]
Function
Frame Detect.
0 = ISOcap frame lock not established
1 = ISOcap frame lock established
00
01
10
11
Min Loop Current
10 mA
12 mA
14 mA
16 mA
Table 53. U66 Bit Map
Table 54. U67 Bit Map
Rev. 0.9
b
,
OHS = 1
current with a ramp instead of a step.
Bits 3:2 (DCV) select the dc termination for the modem.
DCV = 00
Si2493/57/34/15/04. DCV = 01
voltage mode. See "3.5.20.4. DC Termination" on page
141 for details.
Bit 1 (RZ) = 0 (default) allows ringer impedance to be
determined by external components. This impedance is
typically 800–900 kΩ. RZ = 1 enables on-chip synthesis
of a lower ringer impedance for countries, such as
Poland, South Africa, and South Korea.
Bit 0 (RT), Ring Threshold, is used to satisfy various
country ring detect requirements. RT = 0
the ring threshold for 11–22 V
threshold for 17–33 V
of the range are not detected. Signals above the upper
level of the range are always detected.
Function
b
b
causes the hookswitch to turn off the loop
is the lowest voltage mode supported on the
RMS
. Signals below the lower level
RMS
b
. RT = 1
is the next lowest
b
b
(default) sets
sets the ring
AN93
87