Electrical Description - Mitel SX-200 Practices

Circuit Card Descriptions
. 32KX 8 Static Ram with Memory Power Backup
l
Dial Tone Filter
l
PCM Links and Clock Buffers.
Electrical Description
The DX Array is a non-blocking array that contains nine Mite1 DX chips arranged in a
square matrix. The array provides 24 bidirectional links with balanced drivers and
receivers.
The Static RAM provides 32 Kbytes of RAM. To the MPU the RAM appears on the odd
(least significant) byte of the data bus. The FIAM uses the write protect key in use on
the MCC The Static RAM is used to store customer programmed data. Any time a
telephone user enables a function such as Call Forwarding the data (extension number
and type of forwarding) must be saved in a non-volatile memory so that it is not lost
on power down. The Static RAM acts as a buffer for this type of data. When the buffer
is full, the data is transferred to the 3.5 inch Disk Drive Unit. A holdover time of 72 hours
(minimum) is provided by a large 1 F capacitor. As well the RAM is protected from data
corruption during power up and down.
The Dial Tone Filter consists of a codec and an analog filter circuit. The PCM dial tone
is converted to an analog signal, filtered, and reconverted to PCM,
The PCM links use single-ended buffers to interface to the Fiber Interface Modules..
A total of 21 links, grouped in threes, are sent out to the FlMs to address up to seven
Peripheral Bays for a maximum 672-pot-t capacity.
Seven pairs of buffered PCM clocks are provided; one pair per Fiber Interface Module.
Series resistors for EMC waveshaping are added on all clock lines, going out to the
FlMs and the DXArray, to reduce undershoot/overshoot and transmission line effects.
Physical Description
The card measures approximately 127 mm x 247 mm (5.0 in x 9.75 in). It uses surface
mount technology and connects to the Main Control Card component side down via two
96pin DIN connectors (see Figure 2-2).
Tl CLOCK MODULE
Brief Description
2.8
The Tl Clock Module is a digitally controlled oscillator which synchronizes the
system clock to an incoming Tl frame rate clock signal.The Tl Clock Module plugs
into the Main Control Card. The Tl Clock Module is not available with Generic 1001
or Generic 1002.
125 2-4
Revision
0 9109-096-125-NA
Issue
1