AMD
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.
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)
Thesetwocrystalinputpinsconnecttoaninternalparal-
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.
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
Am7968/Am7969
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