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MT89L85 Datasheet(PDF) 3 Page - Mitel Networks Corporation |
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MT89L85 Datasheet(HTML) 3 Page - Mitel Networks Corporation |
3 / 20 page Advance Information MT89L85 3 23 24 R/W Read/Write (Input). This input controls the direction of the data bus lines (D0-D7) during a microprocessor access. 24 26 CS Chip Select (Input). Active low input enabling a microprocessor read or write of control register or internal memories. 25-27 29-33 27-29 31-35 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. 34 1,25,37 VSS Ground Rail. 35-39 41-43 38-42 44-46 STo7- STo0 ST-BUS Outputs 7 to 0 (Three-state Outputs). Serial data output streams. These streams are composed of 32 channels at data rates of 2.048 Mbit/s. 44 47 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. 1 48 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. 6,18, 28,40 6,19,30, 43 NC No Connection. Pin Description Pin # Name Description 44 PLCC 48 SSOP Functional Description With the integration of voice, video and data services into the same network, there has been an increasing demand for systems which ensure that data at N x 64 Kbit/s rates maintain frame sequence integrity while being transported through time slot interchange circuits. Existing requirements demand time slot interchange devices performing switching with constant throughput delay while guaranteeing minimum delay for voice channels. The MT89L85 device provides both functions and allows existing systems based on the MT8985 to be easily upgraded to maintain the data integrity while multiple channel data are transported. The device is designed to switch 64 kbit/s PCM or N x 64 kbit/s data. The MT89L85 can provide both frame integrity for data applications and minimum throughput switching delay for voice applications on a per channel basis. By using Mitel Message mode capability, the microprocessor can access input and output time slots on a per channel basis to control devices such as the MITEL MT8972, ISDN Transceivers and T1/ CEPT trunk interfaces through the ST-BUS interface. Different digital backplanes can be accepted by the MT89L85 device without user's intervention. The MT89L85 device provides an internal circuit that automatically identifies the polarity and format of frame synchronization input signals compatible to ST-BUS and GCI interfaces. Device Operation A functional block diagram of the MT89L85 device is shown in Figure 1. The serial ST-BUS streams operate continuously at 2.048 Mb/s and are arranged in 125 µs wide frames each containing 32 8-bit channels. Eight input (STi0-7) and eight output (STo0-7) serial streams are provided in the MT89L85 device allowing a complete 256 x 256 channel non- blocking switch matrix to be constructed. The serial interface clock for the device is 4.096 MHz, as required in ST-BUS and GCI specifications. Data Memory The received serial data is converted to parallel format by the on-chip serial to parallel converters and stored sequentially in a 256-position Data Memory. The sequential addressing of the Data Memory is generated by an internal counter that is reset by the input 8 kHz frame pulse (F0i) marking the frame boundaries of the incoming serial data streams. Depending on the type of information to be switched, the MT89L85 device can be programmed to perform |
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