~ National ~ Semiconductor - Al Kossow's Bitsavers

15.0 Switching Characteristics (Continued)
Serial Timing-Transmit (Beginning of Frame)
m~'::}:j~~
\xel I-
TXE -beye --
\xesdv-
-- -
r-txesdh
TXO
~
1
X 0 X 1 >OC
C
"'0
00
w
CD
o
n
....
,
......
z
en
w
I\)
.,..
CD
o
n ,
....
TLlF/9345-51
Symbol Parameter Min Max
txch Transmit Clock High Time 36
txcl Transmit Clock Low Time 36
txcyc Transmit Clock Cycle Time 800 1200
txcenh
Transmit Clock to Transmit Enable High
(Note 1)
48
txcsdv Transmit Clock to Serial Data Valid 67
txxsdh
Serial Data Hold Time from
Transmit Clock High
10
Note 1: The NIC issues TXEN coincident with the first bit of preamble. The first bit of preamble is always a 1.
Units
ns
ns
ns
ns
ns
ns
Serial Timing-Transmit (End of Frame, CD Heartbeat)
TXC~~~
I-- \eenl
TXE
- f
TXO BIT N-2
X BIT N-l BIT N I ~
COL
tedl
, ~
-- \dedh
~
TLlF/9345-52
Symbol Parameter Min Max
tcdl Transmit Clock to Data Low 55
tcenl Transmit Clock to TXEN Low 55
tdcdh
TXEN Low to Start of Collision
Detect Heartbeat (Note 1)
0 64
cdhw
Collision Detect Width
2
Note 1: If COL is not seen during the first 64 TX clock cycles following deassertion of TXEN, the CDH bit in the TSR is set.
Units
ns
ns
txcyc
cycles
txcyc
cycles
1-101