MA811

The MA811 is a CMOS device providing digital switching for up to 256 8-bit channels as used in PCM or data systems.8-bit words are received and transmitted at 2.048 Mb/s on each of eight input and eight output lines respectively either in a parallel format with 256 consecutive channels or in serial format with 32 channels multiplexed on to each of the eight lines.

Features of the MA811 are:(1)single 5v supply;(2)low power CMOS design;(3)inputs and outputs TTL compatible;(4)compatible with CCITT 32 channel 2.048 Mb/s format (Rec. 6732);(5)256 input/256 output channels;(6)inputs and outputs can be serial or parallel;(7)variable input/output frame delay; (8)designed to allow easy expansion into larger switching matrices.The device also contains an input buffer/demultiplexor and an output buffer/multiplexor. The function of the input buffer is to receive incoming 8-bit PCM channels in either serial or parallel format and to write each of the 256 channels to the appropriate locations in the speech memory. Similarly, the output buffer will receive the 256 output channels and multiplex them on to the output lines in either serial or parallel  format.

The absolute maximum ratings of the MA811 can be summarized as:(1)operating temperature:0 to +70°C;(2)storage temperature: -55 to +125°C;(3)supply voltage Vdd:-0.3 to 6.5V;(4)voltage on any pin:Vss-0.3 to Vdd+0.3V.For some applications, a 256 channel switching capacity may be insufficient and so the MA811 has been designed such that it may easily be cascaded to form a larger switching matrix (see application notel.The control interface design makes this particularly easy, allowing both the control interface input and output lines and the PCM input or output lines of several DSMs to be simply wired together without the need for additional control logic. When used in this mode, a matrix of DSMs will act simply like a larger DSM. The serial nature of,the control lines, the ease with which devices may be matrixed and the low power CMOS design make the MA811 particularly suitable for densely packed printed circuit boards providing a large switching capacity.