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LANSDALE Semiconductor, Inc.

ML145428

ML145428 DSI PIN DESCRIPTIONS – cont’d

BC, BAUD CLOCK INPUT

This pin serves as an input for an externally supplied 16

times data clock. Otherwise, the BC pin expects a 4.096 MHz

clock signal which is internally divided to obtain the 16 times

clock for the most frequentlly used standard bit rates (see BR1

- BR3 pin description).

BRCLD, 16 TIMES CLOCK INTERNAL OUTPUT

This pin outputs the internal 16 times asynchronous data rate

clock.

BR1, BR2, BR3, BIT RATE SELECT INPUTS

These three pins select the asynchronous bit rate, either

externally supplied at the BC pin (16 times clock) or one of

the internally supplied bit rates. (See Table 1.)

DCO, DATA CHANNEL OUTPUT

This pin is a three–state output pin. Synchronous data is out-

put when DOE is high. This pin will go high impedance when

DOE or RESET are low. When CM is low, synchronous data is

output on DCO on the falling edges of DC as long as DOE is

high. When CM is high, synchronous data is output on DCO on

the rising edges of DC, while DOE is held high. No more than

eight data bits can be output during a given DOE high interval

when CM = high. This feature allows the DSI to interface direct-

ly with the MC145422/26 Universal Digital Loop Transceivers

(UDLT’s) and PABX time division multiplexed highways.

DOE, DATA OUTPUT ENABLE INPUT

See DCO pin description and the SYNCHRONOUS CHAN-

NEL INTERFACE section.

DIE, DATA INPUT ENABLE OUTPUT

See DCI and DCO pin descriptions and the SYNCHRO-

NOUS CHANNEL INTERFACE section.

CM, CLOCK MODE INPUT

See the SYNCHRONOUS CHANNEL INTERFACE section

and the SYNCHRONOUS CLOCKING MODE SUMMARY.

(See Table 2.)

RESET, RESETINPUT

When held low, this pin clears the internal FIFO’s, forces the

TxD asynchronous input to appear high to the DSI’s internal

circuitry, forces TxS and RxS low. When returned high, normal

operation results.

When the RESET input is returned high the DSI’s SYN-

CHRONOUS CHANNEL RECEIVER will not accept or trans-

fer any incoming data words on the DCI pin to the Rx FIFO

until one “flag” word is input at the DCI pin. (Also see RxS

pin description)

DCI, DATA CHANNEL INPUT

Synchronous data is input on this pin on the falling edges of

DC when DIE is high.