Datasheet

DS485
SNLS122C –JULY 1998–REVISED APRIL 2013 www.ti.com
SWITCHING CHARACTERISTICS
Over Supply Voltage and Operating Temperature Ranges, unless otherwise specified
(1)(2)(3)
Symbol Parameter Conditions Min Typ Max Units
t
PLHD
Driver Differential Propagation Delay—Low to High R
L
= 54Ω, C
L
= 100 pF 10 40 65 ns
t
PHLD
Driver Differential Propagation Delay—High to Low 10 39 65 ns
t
SKEW
Differential Skew |t
PHLD
− t
PLHD
| 1 10 ns
t
r
Driver Rise Time 3 25 40 ns
t
f
Driver Fall Time 3 25 40 ns
t
ZH
Driver Enable to Output High C
L
= 100 pF 170 ns
t
ZL
Driver Enable to Output Low C
L
= 100 pF 170 ns
t
LZ
Driver Disable from Output Low C
L
= 15 pF 170 ns
t
HZ
Driver Disable from Output High C
L
= 15 pF 170 ns
t
PLHD
Receiver Differential Propagation Delay—Low to High C
L
= 15 pF (RO) 70 190 320 ns
t
PHLD
Receiver Differential Propagation Delay—High to Low 70 210 320 ns
t
SKEW
Differential Skew |t
PHLD
− t
PLHD
| 20 50 ns
t
ZH
Receiver Enable to Output High C
L
= 15 pF 110 ns
t
ZL
Receiver Enable to Output Low 110 ns
t
LZ
Receiver Disable from Output Low 110 ns
t
HZ
Receiver Disable from Output High 110 ns
f
max
Maximum Data Rate See
(4)
2.5 Mbps
(1) All typicals are given for: V
CC
= +5.0V, T
A
= +25°C.
(2) f = 1 MHz, t
r
and t
f
≤ 6 ns, Z
O
= 50Ω.
(3) C
L
includes jig and probe capacitance.
(4) f
max
is the ensured data rate for 50 ft of twisted pair cable. f
max
may be conservatively determined from the ratio of driver transition time
(t
r
) to the data rate unit interval (1/f
max
). Using a 10% ratio yields f
max
= (0.1)/40 ns = 2.5 Mb/s. Higher data rates may be supported by
allowing larger ratios.
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