Specifications

Chapter 1 – Universal Socket Connectivity
Multi-Tech Systems, Inc. Universal Socket Hardware Guide for Developers (S000342I) 17
Pin Signal Name In/Out Description
59
–
LEDCOL O
LED Collision (Active Low). LED Output. During normal operation, this pin lights the
COL LED to indicate a collision. It flashes at 50ms high and 50ms low when active.
60
–
LEDSPD O
LED Speed (Active Low). LED Output. During normal operation, this pin lights the
SPEED LED to indicate 100Mbps is selected.
61
VCC PWR
DC Input Powe
r
. 3.3V or 5VDC power, depending upon the build.
62
MICV I
Single-Ended Microphone. Single-ended microphone input for dial-up
SocketModem speakerphone and TAM functions.
63
AGND GND
Analog Ground. Analog ground is tied common with DGND on the SocketModem.
To minimize potential ground noise issues, connect audio circuit return to AGND.
64
SPKR O
Speake
r
. Dual purpose output for call progress signals or speakerphone functions.
Call Progress signaling on MT5600SMI, MT5656SMI, MT2492SMI, and
MT2456SMI-22 is a square wave output that can be optionally connected to a low-
cost single-ended speaker; e.g., a sounducer or an analog speaker circuit.
Call progress on the MT9234SMI is an analog output.
Speakerphone Output on the MT5656SMI is under the control of +FCLASS. This is
a single-ended analog output. SPKR is tied directly to the CODEC. One side of a
differential AC output coupled through a 6.8K ohm resistor and capacitor.
Design Considerations
Noise Suppression Design Considerations
Engineering noise-suppression practices must be adhered to when designing a printed circuit board (PCB) containing
the SocketModem. Suppression of noise is essential to the proper operation and performance of the modem itself
and for surrounding equipment.
Two aspects of noise in an OEM board design containing the SocketModem must be considered: on-board/off-board
generated noise that can affect digital signal processing. Both on-board and off-board generated noise that is coupled
on-board can affect interface signal levels and quality. Of particular concern is noise in frequency ranges affecting
modem performance.
On-board generated electromagnetic interference (EMI) noise that can be radiated or conducted off-board is a
separate, but equally important, concern. This type of noise can affect the operation of surrounding equipment. Most
local government agencies have stringent certification requirements that must be met for use in specific
environments.
Proper PC board layout (component placement, signal routing, trace thickness and geometry, etc.) component
selection (composition, value, and tolerance), interface connections, and shielding are required for the board design
to achieve desired modem performance and to attain EMI certification.
Other aspects of proper noise-suppression engineering practices are beyond the scope of this designer guide. The
designer should consult noise suppression techniques described in technical publications and journals, electronics
and electrical engineering text books, and component supplier application notes.
PC Board Layout Guidelines
In a 4-layer design, provide adequate ground plane covering the entire board. In 4-layer designs, power and ground
are typically on the inner layers. All power and ground traces should be 0.05 inches wide.
The recommended hole size for the SocketModem pins is 0.036 in. +/-0.003 in. in diameter. Spacers can be used to
hold the SocketModem vertically in place during the wave solder process.
All creepages and clearances for the SocketModem have been designed to meet requirements of safety standards
EN60950 or EN60601. The requirements are based on a working voltage of 125V or 250V. When the recommended
DAA* circuit interface is implemented in a third party design, all creepage and clearance requirements must be strictly
followed in order to meet safety standards. The third party safety design must be evaluated by the appropriate
national agency per the required specification.
User accessible areas: Based on where the third party design is to be marketed, sold, or used, it may be necessary
to provide an insulating cover over all TNV exposed areas. Consult with the recognized safety agency to determine
the requirements.
Note: Even if the recommended design considerations are followed, there are no guarantees that a particular system
will comply with all the necessary regulatory requirements. It is imperative that specific designs be completely
evaluated by a qualified/recognized agency.
*DAA stands for Data Access Arrangement. DAA is the telephone line interface of the SocketModem.