ISO-CMOS
Pin Description (continued)
Pin #*
26, 27
28 - 33
34
35
36
37
38
39
40
Name
Description
MT8816
X13, X12
X13 and X12 Analog (Inputs/Outputs):
these are connected to the X13 and X12 rows of
the switch array.
X5-X0
NC
Y0
CS
Y1
DATA
Y2
V
DD
X5-X0 Analog (Inputs/Outputs):
these are connected to the X5-X0 rows of the switch
array.
No Connection.
Y0 Analog (Input/Output):
this is connected to the Y0 column of the switch array.
Chip Select (Input):
this is used to select the device. Active High.
Y1 Analog (Input/Output):
this is connected to the Y1 column of the switch array.
DATA (Input):
a logic high input will turn on the selected switch and a logic low will turn off
the selected switch. Active High.
Y2 Analog (Input/Output):
this is connected to the Y2 column of the switch array.
Positive Power Supply.
* Plastic DIP and CERDIP only
Functional Description
The MT8816 is an analog switch matrix with an array
size of 8 x 16. The switch array is arranged such that
there are 8 columns by 16 rows. The columns are
referred to as the Y inputs/outputs and the rows are
the X inputs/outputs. The crosspoint analog switch
array will interconnect any X I/O with any Y I/O when
turned on and provide a high degree of isolation
when turned off. The control memory consists of a
128 bit write only RAM in which the bits are selected
by the address inputs (AY0-AY2, AX0-AX3). Data is
presented to the memory on the DATA input. Data is
asynchronously written into memory whenever both
the CS (Chip Select) and STROBE inputs are high
and are latched on the falling edge of STROBE. A
logical “1” written into a memory cell turns the
corresponding crosspoint switch on and a logical “0”
turns the crosspoint off. Only the crosspoint switches
corresponding to the addressed memory location are
altered when data is written into memory. The
remaining switches retain their previous states. Any
combination of X and Y inputs/outputs can be
interconnected by establishing appropriate patterns
in the control memory. A logical “1” on the RESET
input will asynchronously return all memory locations
to logical
“0”
turning
off
all
crosspoint
switches regardless of whether CS is high or low.
Two voltage reference pins (V
SS
and V
EE
) are
provided for the MT8816 to enable switching of
negative analog signals.
The range for digital
signals is from V
DD
to V
SS
while the range for analog
signals is from V
DD
to V
EE
. V
SS
and V
EE
pins can be
tied together if a single voltage reference is needed.
Address Decode
The seven address inputs along with the STROBE
and CS (Chip Select) are logically ANDed to form an
enable signal for the resettable transparent latches.
The DATA input is buffered and is used as the input
to all latches. To write to a location, RESET must be
low and CS must go high while the address and data
are set up. Then the STROBE input is set high and
then low causing the data to be latched. The data
can be changed while STROBE is high, however, the
corresponding switch will turn on and off in
accordance with the DATA input. DATA must be
stable on the falling edge of STROBE in order for
correct data to be written to the latch.
3-47
MITEL [ MITEL NETWORKS CORPORATION ]
