4

Symbol

Parameter

Units

Min.

Typ.

Max.

Setup Time

nsec

1.5

Hold Time

nsec

1.0

Transmitter Latency

nsec

3.5

bits

4.4

Frame Demux and

Byte Sync

The FRAME DEMUX AND BYTE

SYNC block is responsible for

restoring the 10-bit parallel

data from the high speed serial

bit stream. This block is also

responsible for recognizing the

comma character (or a K28.5

character) of positive disparity

(0011111xxx). When recognized,

the FRAME DEMUX AND BYTE

SYNC block works with the RX

PLL/CLOCK RECOVERY block

to properly align the receive byte

clocks to the parallel data. When

a comma character is detected

and realignment of the receiver

byte clocks (RBC1/RBC0) is

necessary, these clocks are

stretched, not slivered, to the

next possible correct alignment

position. These clocks will be fully

aligned by the start of the second

2-byte ordered set. The second

comma character received shall

be aligned with the rising edge of

RBC1. As per the 8B/10B encoding

scheme, comma characters must

not be transmitted in consecutive

bytes to allow the receiver byte

clocks to maintain their proper

recovered frequencies.

Output Drivers

The OUTPUT DRIVERS present

the 10-bit parallel recovered data

byte properly aligned to the receive

byte clocks (RBC1/RBC0),

as shown in Figure 5. These

output data buffers provide

TTL compatible signals.

Signal Detect

The SIGNAL DETECT block

examines the differential

amplitude of the inputs

± DINB.

When this input signal is too

small, it outputs a logic 0 at

SIG_DET (refer to SIG_DET pin

definition for detection thresholds).

When the signal at

± DINB is

of a valid amplitude, SIG_DET

is set to logic 1.

Note:

1. The transmitter latency, as shown in Figure 4, is defined as the time between the

latching in of the parallel data word (as triggered by the rising edge of the transmit

byte clock, REFCLK) and the transmission of the first serial bit of that parallel word

at either output pair (defined by the rising edge of the first bit transmitted).

HDMP-1638 (Transmitter Section)

Timing Characteristics