Si2439-A-FM18-EVB Silicon Labs, Si2439-A-FM18-EVB Datasheet - Page 10

• Manufacturer Part Number: Si2439-A-FM18-EVB
• Description: Networking Development Tools 38pin Si2439+ Si3018 ISOmodem Eval Board
• Manufacturer: Silicon Labs
• Type: Network Controller & Processorr

Specifications of Si2439-A-FM18-EVB

• Rohs: yes
• Tool Is For Evaluation Of: Si2439
• Data Rate: 56 Kbps
• Interface Type: RJ-11, RS-232, SPI, UART, USB
• Operating Supply Voltage: 3.3 V

Si2493/57/34/15/04
Global ISOmodem-EVB
2.1.9. Direct Access Interface
While the motherboard supplies power through J8, J9,
or USB, power-on reset, and an RJ–11 jack for the
modem, the direct access interface (J103) is used to
connect the motherboard to an embedded system. J103
provides access to all Si2493/57/34/15/04 signals
available on the daughter card.
It is necessary to remove the jumper on JP23 to disable
both the RS-232 and USB interface and prevent signal
contention.
2.1.10. PCM Interface (24-Pin FT Only)
The
demonstrated using the voice motherboard, not with this
EVB.
2.1.11. AOUT Call Progress Audio Output
Call progress audio output is provided by the Si2493/57/
34/15/04 on the AOUT pin as a PWM signal. This signal
allows the user to monitor call progress signals, such as
dial tone, DTMF dialing, ring, busy signals, and modem
negotiation. Control of this signal is provided by AT
commands and register settings described in the
introduction. The AOUT signal is connected to an on
board amplifier, for a high-quality output. AOUT can
also be connected to a summing amplifier or multiplexer
in an embedded application as part of an integrated
audio system.
2.1.11.1. AOUT Audio Processing
The AOUT signal discussed in this section leaves the
Si2493/57/34/15/04 is processed (demodulated) by a
high pass filter: (R133,134,135, and C24, C25, 26,
C27). It is critically important to not put a dc load on the
AOUT pin since the pin also acts as a modem feature
control on reset and is internally weakly pulled up. Any
unintentional dc load on AOUT prevents proper
10
Si2493/57/34/15/04
Carrier Detect
Received Data
Transmit Data
Data Terminal Ready
Signal Ground
Data Set Ready
Ready to Send
Clear to Send
Ring Indicator
*Note: JP6 jumper option.
J1 Name
PCM
interface
J1 Symbol
Table 3. DB9 Pin Connections
RXD
DTR
DSR
TXD
RTS
CTS
CD
SG
RD
can
Rev. 0.7
be
J1 Pin
4*
6*
7*
1
9
2
5
3
8
*
*
operation of the modem. See “AN93: Si3457/34/15/04
Modem Designer’s Guide” for more details on the
features controlled by pin strapping.
Since this PWM signal swings rail to rail and is simply
filtered by a low pass filter to acquire the audio. It is
important to keep the power supply to the modem free
of noise in the audio spectrum.
2.1.11.2. The Audio Output Amplifier (LM4819)
The Power amplifier on the EVB is powered by a current
limited 4.2 V supply. The current limit is implemented in
the
development and is not needed for a production design.
This amplifier can drive an 8  speaker with 200 mW of
Call progress audio (i.e., ISOmodem's call progress
dialing and negotiation tones).
The power amplifier itself is a low cost, rugged H bridge
type device. There are several pin compatible designs
from multiple vendors that can provide alternate price/
power tradeoffs for this amplifier. This power amp can
be shut down by removing jumper JP12. The signal at
JP12 can also be tied to a control signal to allow the
host to shut down the amplifier. The customer can
change the values of R172 and R173 when integrating
the EVB to his system, but should keep the RC formed
by C37 and R173 at a 50 Hz or higher corner to avoid a
power-on thump.
2.1.11.3. The Call Progress Speaker
The Call progress speaker, Regal RE-2308-NL is
connected to the amplifier via a jumper, JP14. If another
speaker is to be connected then it is necessary to
remove JP14 and connect the external speaker to JP11,
Pins 1 and 4. It is important to remember that the
speaker signal is differential. Both the output pins are
driven outputs and must not be grounded.
EVB
Si2493/57/34/15/
See note
See note
See note
See note
04 Pin
because
10
17
11
9
6
it
Si2493/57/34/15/
is
RTS/RXCLK
DCD/EESD
INT/AOUT
04 Name
ESC/RI
intended
GND
RXD
TXD
CTS
RI
for
HW/SW