SI2493-C-FT Silicon Laboratories Inc, SI2493-C-FT Datasheet - Page 158

• Manufacturer Part Number: SI2493-C-FT
• Description: 56 KBPS, V.92 ISOMODEM SYSTEM-SIDE - LEAD-FREE TSSOP 0 TO 7
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-FT

• 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: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN93
158
within 200 ms after the carriage return. The reset
recovery time (the time between a hardware reset or
the carriage return of an ATZ command and the time
the next AT command can be executed) is
approximately 300 ms. When a data connection is
being established, do not try to escape to the
command mode until after the protocol message.
Register Configurations
The ATS$ command lists the contents of all S-
Registers, and the AT:R command lists the contents
of all U-Registers.
Si3018/10 and/or Associated Components
If the modem goes off-hook and draws loop current
as a result of giving the ATH1 command, go to the
Si3018/10 Troubleshooting section.
If the modem does not go off-hook and draw loop
current as a result of giving the ATH1 command and
receiving an “OK” message, begin troubleshooting
with the isolation capacitor at the Si2457/34/15.
First, check all solder joints on the isolation
capacitors, Si3018/10, and associated external
components. If no problems are found, proceed to
the following ISOcap Troubleshooting section to
verify whether the problem is on the Si2493/57/34/
15/04 or the Si3018/10 side of the isolation
capacitor. If the problem is found to be on the
Si2493/57/34/15/04 side, check C50, C51, C53, the
corresponding PCB traces, and the Si2493/57/34/
15/04 pins. Correct any problems. If no problems are
found with the external components, replace the
Si2457/34/15.
If the problem is found to be on the Si3018/10 side of
the isolation capacitor, go to the Si3018/10
Troubleshooting section.
The modem does NOT respond with an “OK” to the
command “AT<cr>”.
This indicates that the host processor/software is not
communicating with the modem controller, and the
problem can be isolated as follows.
Si2493/57/34/15/04 Clock is Oscillating
First, be sure the Si2493/57/34/15/04 is properly
reset and RESET, pin 12, is at 3.3 V. Next, check the
DTE connection with the host system. If this does
not isolate the problem, go to the Host Interface
Troubleshooting section.
Si2493/57/34/15/04 Clock is Not Oscillating
Check the voltage on the Si2493/57/34/15/04, pins 5
and 21, to be sure the chip is powered. Also, check
that pins 6 and 20 are grounded. Next, check the
solder joints and connections (PCB traces) on C40,
C41, Y1, and the Si2493/57/34/15/04 Pin 1 and Pin
2. Measure C26 and C27 (or replace them with
known good parts) to ensure that they are the
Rev. 0.9
Host Interface Troubleshooting
The methods described in this section are useful as a
starting point for debugging a prototype system or as a
continuation of the troubleshooting process described
previously. The procedures presented in this section
require
evaluation board and data sheet. This section describes
how to substitute the evaluation board for the entire
modem circuitry in the prototype system. Substituting a
known operational modem can help to quickly isolate
problems. The first step is to substitute the evaluation
board for the complete modem solution in the prototype
system. This immediately demonstrates whether any
modem functionality problems are in the prototype
modem circuitry or in the host processor, interface, or
software.
Isolation Capacitor Troubleshooting
Connect the evaluation board isolation capacitor to
Prototype Modem Si3018/10. Remove C1 on the
evaluation board and on the prototype system. Solder
one end of the evaluation board, C1, to the Si2457/34/
correct value. If these steps do not isolate the
problem, replace the Si2457/34/15.
Verify Si2457/34/15URT-EVB Functionality
Connect the evaluation board to a PC and a phone
line or telephone line simulator. Using a program,
such as HyperTerm, make a data connection
between the evaluation board and a remote modem.
Remove power and the RS232 cable from the
evaluation board and proceed to the next step.
Connect Evaluation Board to Prototype System
Completely disconnect the embedded modem from
the host interface in the prototype system. Connect
the Si2457/34/15URT-EVB to the host interface
using JP3 as described in the Si2457/34/15URT-
EVB data sheet section titled Direct Access
Interface. This connection is illustrated in Figure 30.
Be sure to connect the evaluation board ground to
the prototype system ground. Power up and
manually reset the evaluation board, then power up
the prototype system and send “AT<cr>.” If an “OK”
response is received, make a connection to the
remote modem as in the previous step. If no “OK”
response is received, debug host interface and/or
software. If a connection is successfull, go to the
next step to isolate the problem in the prototype
modem.
An alternative approach is to connect the prototype
modem to the Si2457/34/15URT-EVB motherboard
in place of the daughter card and use a PC and
HyperTerm to test the prototype modem. See Figure
Figure 31 for details.
a
known
good
Si2457/34/15URT-EVB