SI2400URT-EVB Silicon Laboratories Inc, SI2400URT-EVB Datasheet - Page 5

• Manufacturer Part Number: SI2400URT-EVB
• Description: BOARD EVAL FOR SI2400 ISOMODEM
• Manufacturer: Silicon Laboratories Inc
• Series: ISOmodem®r

Specifications of SI2400URT-EVB

• Main Purpose: Telecom, Modem
• Embedded: No
• Utilized Ic / Part: SI2400
• Primary Attributes: Dual RJ-11 Connection to Phone Line, Audio Connector
• Secondary Attributes: RS-232, TTL Serial & USB Interfaces
• Processor To Be Evaluated: Si2400
• Interface Type: RS-232, USB
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant
• Other names: 336-1166

interrupting the connection between the two modems,
type “+++.” Approximately two seconds later, “O” will
appear. The modem is now in command mode and will
accept “AT” commands. To return to the data mode,
type “ATO.” The modem resumes the data connection
and no longer accepts AT commands. Type “ATH” to
terminate the data connection.
3. Si2400URT-EVB Functional
The Si2400URT-EVB is a multipurpose evaluation
system. The modem daughter card illustrates the small
size and small number of components required to
implement an entire controller-based modem with
global telecommunications compatibility. The daughter
card can be used independently of, or in conjunction
with, the motherboard. The motherboard adds features
that enhance the ease of evaluating the many
capabilities of the Si2400 ISOmodem
3.1. Motherboard
The motherboard provides a convenient interface to the
Si2400DC (daughter card). The versatile power supply
allows for a wide range of ac and dc voltages to power
the board. RS-232 transceivers and a DB9 connector
allow the Si2400URT-EVB to be easily connected to a
PC or other terminal device. Jumper options allow direct
access to the LVCMOS/TTL level serial inputs to the
Si2400, bypassing the RS-232 transceivers or USB
interface. This is particularly useful for directly
connecting the Si2400 to embedded systems.
The Si2400URT-EVB motherboard connects to the
daughter card through two connectors, JP1 and JP2.
JP1 is an 8x2 socket providing connection to all Si2400
digital signals and regulated 3.3 V power for the Si2400.
The Si2400 digital signals appearing at JP1 (daughter
card interface) are LVCMOS and TTL compatible. The
Si2400DC must be powered by 3.3 V. The motherboard
is factory-configured for 3.3 V with JP7 pins 1 and 2.
JP2 is a 4x1 socket providing connection between the
daughter card and the RJ-11 phone jack.
3.1.1. Voltage Regulator/Power Supply
The input voltage to either J3 or J4 must be between 7.5
and 13.5 V dc or 7.5 and 13.5 V
motherboard includes a diode bridge (D1–D4) to guard
against a polarity reversal of the dc voltage or to rectify
an ac voltage. The power source must be capable of
continuously supplying at least 100 mA. C50 serves as
a filter cap for an ac input. The voltage regulator, U1,
provides 5 V for the motherboard and the input for
voltage regulator U2, which outputs 3.3 V for use on the
motherboard and to power the daughter card. Si24xxDC
power consumption can be measured by placing a
Description
®
.
PEAK
ac. The
Rev. 0.7
meter between pins 1 and 2 of JP7. The connection
between JP7 pins 1 and 2 must be made at all times
when power is applied to the evaluation board either
through a jumper block or a low-impedance meter to
avoid damage to the daughter card. Power is supplied
to U2 through D5 from the USB.
3.1.2. Reset Circuitry
The Si2400 requires a reset pulse to remain low for at
least 5.0 ms after the power supply has stabilized during
the powerup sequence or for at least 5.0 ms during a
power-on reset, then go high with a rise time <100 ns.
Most production Si2400 modem chipset applications
require that RESET be controlled by the host processor.
Certain Si2400 operation modes, including Powerdown,
require a hardware reset to recover.
The Si2400URT-EVB contains two reset options, an
automatic
(default), and a manual reset switch (S1) to permit
resetting the chip without removing power. A reset,
regardless of the mechanism, causes all modem
settings to revert to factory default values. See Figure 6
on page 12 and Figure 8 on page 14 for the reset circuit
schematic.
3.1.3. DS1818
The DS1818 is a small, low-cost device that monitors
the voltage on V
V
active-low reset pulse. Upon powerup, the DS1818 also
outputs an active low reset pulse for 220 ms after V
reaches 90% of the nominal 3.3 V value. The DS1818
outputs a 220 ms reset pulse any time the power supply
voltage exceeds the 3.3 V ±10% window.
3.1.4. Manual Reset
The manual reset switch, S1, performs a power-on
reset. This resets the Si2400 to factory defaults without
turning off power. If S1 is used in conjunction with U6,
pressing S1 activates the reset monitor in the DS1818
and produces a 220 ms active low reset pulse.
3.1.5. Interface Selection
The serial interface of the Si2400USB-EVB can be
connected to a computer terminal, embedded system,
or any other Data Terminal Equipment (DTE) via a
standard RS-232 interface, USB interface, or through a
direct TTL serial interface.
The Si2400 can be tested as a standard data modem by
connecting the Si2400USB-EVB to a personal computer
or other DTE, power supply, and a phone line. A PC can
communicate with the Si2400USB-EVB using a
standard terminal program, such as HyperTerm or
ProComm.
Jumper settings determine how the Si2400USB-EVB is
D
drops below 3.0 V, the DS1818 provides a 220 ms
power-on reset
D
and an external reset pushbutton. If
Si2400URT-EVB
device,
U3 (DS1818)
D
5