Specifications

AN93
182 Rev. 0.9
If the connection attempt is not successful, the problem
lies with the Si3008 and/or associated components.
Proceed to " Si3008 Troubleshooting" below.
This diagnosis can be validated by connecting the Host
isolation capacitors to the Si3008 on the evaluation
board as shown in Figure 48.
Si3008 Troubleshooting
Start by measuring the on-hook and off-hook voltages at
the Si3008 pins with respect to IGND (pin 15). Compare
these voltages to those in Figure 49. This may indicate
an area of circuitry to investigate further using the
Component Troubleshooting techniques. The voltages
you measure should be close to (although not exactly
the same as) those in the figure.
If any of the on-hook and off-hook Si3008 pin voltages
are significantly different from those in Figure 49 and
nothing seems wrong with the external circuitry after
using the Component Troubleshooting techniques,
replace the Si3008.
Component Troubleshooting
A digital multimeter is a valuable tool to verify resistance
across components, diode direction, transistor polarity
and node voltages. During this phase of
troubleshooting, it is highly useful to have a known good
Si24xxURT-EVB to compare against measurements
taken from the prototype system. The resistance values
and voltages listed in Figure 50 and Tables 111 and 112
will generally be sufficient to troubleshoot all but the
most unusual problems.
Start with power off and the phone line disconnected.
Measure the resistance of all Si3008 pins with respect
to pin 9 (IGND). Compare these measurements with the
values in Figure 50. Next, measure the resistance
across the components listed in Table 111 and compare
the readings to the values listed in the table. Finally,
using the diode checker function on the multimeter,
check the polarities of the transistors as described in
Table 112. The combination of these measurements
should indicate the faulty component or connection. If
none of the measurements appears unusual and the
prototype modem is not working, replace the Si3008.
Figure 45. Test the Host Interface
Host
Controller
Host
UART
Si24xx
Si3008 Discretes
RS232
Transceiver
Si24xx Si3008 Discretes
EVB
Prototype System
To
Phone
Line
 Connect prototype system ground to EVB ground
 Disable RS232 transceiver outputs (check evaluation board data sheet)
 Disconnect prototype modem interface
 Connect the evaluation board to the target system