AM7968 datasheet(13/127 Pages) AMD

13 / 127 page

AMD

Am7968/Am7969

swings, which are referenced to +5.0 V. When

SERIN–

is grounded, the Am7969 is put into Test Mode;

SERIN+

becomes a single-ended ECL input, the PLL clock gen-

erator is bypassed, and

X1 determines the bit rate

(rather than the byte rate). Both pins have internal pull

down resistors which cause unterminated inputs to

stay low.

VCC1, VCC2

Power Supply

VCC1 and VCC2 are +5.0 volt nominal power supply pins.

VCC1 powers TTL I/O, and VCC2 powers internal Logic

and Analog circuitry.

VLTN

Violation (TTL Output)

The rising edge of this output indicates that a transmis-

sion error has been detected. It changes state at the

same time

DOi or COi change and will be followed by

either

DSTRB or CSTRB. This pin goes LOW when the

next valid byte is decoded.

X1, X2

Crystal Oscillator Inputs (Inputs)

These two crystal input pins connect to an internal paral-

lel/mode oscillator which oscillates at the fundamental

frequency external crystal. During normal operation, the

byte rate is set by the crystal frequency. Alternatively,

X1 can be driven by an external frequency source. In

multiple TAXI systems, this external source could be a

TAXI Transmitter’s

CLK output or an external TTL fre-

quency source.

AM7968 Datenblatt(PDF) 13 Page - Advanced Micro Devices