693

TRx I/O Definition (cont’d.)

Name

Pin

Type

Signal

VCC_RXTTL

29

S

TTL Power Supply: Normally 5 volts. Used for all TTL receiver output

37

buffer cells.

42

RBC1

30

O-TTL

Receiver Byte Clocks: The receiver section recovers two 53.125 MHz

RBC0

31

receive byte clocks. These two clocks are approximately 180 degrees out

of phase. The receiver parallel data outputs are alternatively clocked on

the rising edge of these clocks. RBC1 aligns and outputs the comma

character (for byte alignment) when detected.

GND_RXTTL

32

S

TTL Receiver Ground: Normally 0 volts. Used for the TTL output cells

33

of the receiver section.

46

RX[0]

45

O-TTL

Data Outputs: One 10 bit data byte. RX[0] is the first bit received.

RX[1]

44

RX[0] is the least significant bit.

RX[2]

43

RX[3]

41

RX[4]

40

RX[5]

39

RX[6]

38

RX[7]

36

RX[8]

35

RX[9]

34

BYTSYNC

47

O-TTL

Byte Sync Output: An active high output. Used to indicate detection of

either a comma character or a K28.5 special character of positive

disparity. It is only active when ENBYTSYNC is enabled.

RXCAP0

48

C

Loop Filter Capacitor: A loop filter capacitor for the internal PLL is

RXCAP1

49

connected across the RXCAP0 and RXCAP1 pins.

(typical value = 0.01

µF).

VCC_RXA

50

S

Analog Power Supply: Normally 5 volts. Used to provide a clean supply

line for the PLL and high-speed analog cells.

GND_RXA

51

S

Analog Ground: Normally 0 volts. Used to provide a clean ground

plane for the receiver PLL and high-speed analog cells.

-DIN

52

HS_IN

Serial Data Inputs: High-speed inputs. Serial data is accepted from the

+DIN

54

± DIN inputs when LOOPEN is low.

VCC_RXHS

53

S

High-Speed Supply: Normally 5 volts. Used only for the high-speed

55

receiver cell (HS_IN). Noise on this line should be minimized for best

operation.

GND_RXHS

56

S

Ground: Normally 0 volts.

VCC_TXECL

60

S

High-Speed ECL Supply: Normally 5 volts. Used only for the last stage

of the high-speed transmitter output cell (HS_OUT) as shown in

bypassed to a ground plane.

VCC_TXHS

63

S

High-Speed Supply: Normally 5 volts. Used by the transmitter side

for the high-speed circuitry. Noise on this line should be minimized

for best operation.

-DOUT

61

HS_OUT Serial Data Outputs: High-speed outputs. These lines are active when

+DOUT

62

LOOPEN is set low. When LOOPEN is set high, these outputs are held

static.

GND_TXHS

64

S

Ground: Normally 0 volts.