MT9085 Mitel Networks Corporation, MT9085 Datasheet - Page 11

• Manufacturer Part Number: MT9085
• Description: CMOS PAC - Parallel Access Circuit
• Manufacturer: Mitel Networks Corporation

2048 Channel Digital Space-Time Switch
Application
A 2048 channel serial time-space digital switch
design is illustrated in Figure 12.
The main switching function is accomplished using
three MT9080s (SMXs). Two SMXs function as the
data memory, while the third is operated in Connect
Memory mode.
more information on this configuration. The Serial to
parallel conversion for 2048 channels is handled by
two PACs. PAC #1a and PAC #1b.
configured for 2.048 Mbit/s operation (2/4S=0). The
MCB input is tied low in both devices. The parallel
data bus on each of the devices will be actively
driven for one C16 clock period. The CKD input is
set low in one of the devices and set high in the
other. This will cause the output timing of the two
PACs to be off set by one C16 clock period.
Consequently, the parallel output of one device will
be disabled while the other is active.
The
accomplished with two PACs.
common SMX parallel bus is clocked into each PAC
in alternate clock periods.
The timing source generates a 16.384 MHz clock
phase locked to a 4.096 MHz clock. The framing
signal input to PAC #1a at F0i should meet the
requirements specified in this data sheet. In some
Figure 10 - Mapping of Data Memory and PAC Control Functions on Connection Memory Data Bits
Ex. Serial Stream 4, Channel 3 Corresponds to SMX Channel Number 100 (Hex 0064)
parallel
Figure 11 - Decoding SMX Channel Number from Serial Stream & Channel Address
15
Not
Used
14
to
Refer to the SMX data sheet for
13
serial
Mode Control - DM-1 or DM-2
Unused
12
conversion
ME - Message Enable
11
Data from the
OE - Output Enable
10
1024 Switch Configuration
Both are
is
9
4
also
8
3
Serial Channel
Channel
Address
Number
applications where a master 16.384 MHz oscillator is
used for system timing, the C4i and F0i clocks could
be derived directly from it.
The DFPo and DFPo generated by PAC #1a are
used to switch the mode of operation of the Data
Memory SMXs between Counter and External
modes and also serve as the frame pulse for the two
SMXs. Because DFPo and DFPo are complementary
signals, one of the two SMXs is operated in the
Counter mode while the second one is operated in
the External mode. The states of the other control
inputs, R/W and ODE, are changed accordingly.
The SMX configured as the Connection Memory, is
fed a frame pulse from PAC #1b.
alignment of CFPo with respect to DFPo ensures
that timing requirements for proper operation of the
SMXs are met. Refer to the SMX data sheet for
more information on the timing requirements.
The maximum delay through the switch is two
frames.
integrity
configurations.
For more information, see Mitel’s Application Note
MSAN-135, “Design of Large Digital Switching
Matrices using the SMX/PAC“ (in this data book)
and Application Sheet MSAS-62 “16.384 MHz Clock
Generation for SMX/PAC“ (available from Mitel).
2
7
1
6
Channels are double buffered and frame
is
0
5
maintained
4
4
3
Address
Stream
CMOS
3
Address
Stream
2
2
for
1
1
all
0
MT9085
The phase
0
switching
2-135