MT8809 Data Sheet
3
Zarlink Semiconductor Inc.
Functional Description
The MT8809 is an analog switch matrix with an array size of 8 x 8. The switch array is arranged such that there are
8 columns by 8 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 64 bit write only RAM in which the bits are
selected by the address inputs (AY0-AY2, AX0-AX2). 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 low and are
latched on the rising 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 “0” 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.
Address Decode
The six 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 high and CS must go low while the address and data are set up. Then the STROBE
input is set low and then high causing the data to be latched. The data can be changed while STROBE is low,
however, the corresponding switch will turn on and off in accordance with the DATA input. DATA must be stable on
the rising edge of STROBE
in order for correct data to be written to the latch.
19 V
DD
Positive Power Supply.
20-23 X7, X5,
X3, X1
X7, X5, X3 and X1 Analog (Inputs/Outputs): these are connected to the X7, X5, X3 and
X1 rows of the switch array.
24-26 AX0-AX2 AX0 - AX2 Address Lines (Inputs).
27, 28 AY0, AY1 AY0 and AY1 Address Lines (Inputs).
Pin Description
Pin # Name Description