MT8812 Data Sheet
3
Zarlink Semiconductor Inc.
Functional Description
The MT8812 is an analog switch matrix with an array size of 8 x 12. The switch array is arranged such that there
are 8 columns by 12 rows. The columns are referred to as the Y input/output lines and the rows are the X
input/output lines. The crosspoint analog switch array will interconnect any X line with any Y line when turned on
and provide a high degree of isolation when turned off. The control memory consists of a 96 bit write only RAM in
which the bits are selected by the address input lines (AY0-AY2, AX0-AX3). Data is presented to the memory on the
DATA input line. Data is asynchronously written into memory whenever the STROBE input is high and is 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 lines can be interconnected by establishing appropriate patterns in the control memory. A
logical “1” on the RESET input line will asynchronously return all memory locations to logical “0” turning off all
crosspoint switches.
Address Decode
The seven address lines along with the STROBE input 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 while the address and data lines 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. Data must be stable on the falling edge of
STROBE in order for correct data to be written to the latch.
20 22 V
SS
Ground Reference.
21 23 Y4 Y4 Analog (Input/Output): this is connected to the Y4 column of the switch array.
22, 23 24,25 AX1,AX2 X1 and X2 Address Lines (Inputs).
24, 25 26,27 AY0,AY1 Y0 and Y1 Address Lines (Inputs).
26, 27 28-31 NC No Connection.
28 - 33 32-37 X5-X0 X5-X0 Analog (Inputs/Outputs): these are connected to the X5-X0 rows of the
switch array.
34 38,39 NC No Connection.
35 40 Y0 Y0 Analog (Input/Output): this is connected to the Y0 column of the switch array.
36 - NC No Connection.
37 41 Y1 Y1 Analog (Input/Output): this is connected to the Y1 column of the switch array.
38 42 DATA DATA (Input): a logic high input will turn on the selected switch and a logic low will
turn off the selected switch. Active High.
39 43 Y2 Y2 Analog (Input/Output): this is connected to the Y2 column of the switch array.
40 44 V
DD
Positive Power Supply.
Pin Description
Pin #
Name Description
