Usb interface – Rainbow Electronics AT89C5122 User Manual
Page 200
200
AT8xC5122/23
4202E–SCR–06/06
This diagram indicates when signals are clocked internally. The time it takes the signals
to propagate to the pins, however, ranges from 25 to 125 ns. This propagation delay is
dependent on variables such as temperature and pin loading. Propagation also varies
from output to output and component. Typically though (T
A
=25
°
C fully loaded) RD and
WR propagation delays are approximately 50 ns. The other signals are typically 85 ns.
Propagation delays are incorporated in the AC specifications.
USB Interface
Rise Time
Fall Time
V
CRS
Differential
Data Lines
90%
10%
90%
10%
t
R
t
F
V
Hmin
V
Lmax
Symbol
Parameter
Min
Typ
(5)
Max
Unit
t
R
Rise Time
4
20
ns
t
F
Fall Time
4
20
ns
t
FDRATE
Full-speed Data Rate
11.9700
12.0300
Mb/s
V
CRS
Crossover Voltage
1.3
2.0
V
t
DJ1
Source Jitter Total to next transaction
-3.5
3.5
ns
t
DJ2
Source Jitter Total for paired
transactions
-4
4
ns
t
JR1
Receiver Jitter to next transaction
-18.5
18.5
ns
t
JR2
Receiver Jitter for paired transactions
-9
9
ns