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MT8985
Data Sheet
3
Zarlink Semiconductor Inc.
Pin Description
Pin #
Name
Description
40
DIP
44
PLCC
44
QFP
1
2
40
DTA
Data Acknowledgement
(Open Drain Output). This active low output indicates that
a data bus transfer is complete. A pull-up resistor is required at this output.
ST-BUS Input 0 to 7 (Inputs).
Serial data input streams. These streams have 32
channels at data rates of 2.048 Mbit/s.
2-9
3-5
7-11
41-43
1-5
STi0-
STi7
10
12
6
V
DD
+5 Volt Power Supply rail.
11
13
7
F0i
Frame Pulse (Input):
This input accepts and automatically identifies frame
synchronization signals formatted according to different backplane specifications
such as ST-BUS and GCI.
12
14
8
C4i
A0-A5
Address 0 to 5 (Inputs).
These lines provide the address to MT8985 internal
registers.
DS
Data Strobe (Input).
This is the input for the active high data strobe on the
microprocessor interface. This input operates with CS to enable the internal read and
write generation.
Clock (Input).
4.096 MHz serial clock for shifting data in and out of the data streams.
13-18 15-17
19-21
22
9-11
13-15
16
19
20
23
17
R/W
Read/Write (Input).
This input controls the direction of the data bus lines (D0-D7)
during a microprocessor access.
21
24
18
CS
Chip Select (Input).
Active low input enabling a microprocessor read or write of
control register or internal memories.
D7-D0
Data Bus 7 to 0 (Bidirectional).
These pins provide microprocessor access to data
in the internal control register, connect memory high, connect memory low and data
memory.
V
SS
Ground Rail.
STo7-
STo0
streams are composed of 32 channels at data rates of 2.048 Mbit/s.
ODE
Output Drive Enable (Input).
This is an output enable for the STo0 to STo7 serial
outputs. If this input is low STo0-7 are high impedance. If this input is high each
channel may still be put into high impedance by software control.
CSTo
Control ST-BUS Output (Output).
This output is a 2.048 Mb/s line which contains
256 bits per frame. The level of each bit is controlled by the contents of the CSTo bit
in the Connect Memory high locations.
NC
No Connection.
22-29 25-27
29-33
19-21
23-27
30
34
28
31-38 35-39
41-43
44
29-33
35-37
38
ST-BUS Outputs 7 to 0 (Three-state Outputs).
Serial data output streams. These
39
40
1
39
6, 18,
28,
40
12,22
34,
44