cabling can be as long as 4,000 feet, RS-485
transceivers are equipped with a wide (-7V to
+12V) common mode range to accomodate
ground potential differences. Because the
RS-485 protocol is a differential interface, data
is virtually immune to noise in the transmission
line.
Receiver...
The
SP3488
and the
SP3489
receivers have
differential inputs with an input sensitivity
as low as +100mV. Input impedance of the
receivers is typically 15KΩ (12KΩ minimum).
A wide common mode range of -7V to +12V
allows for large ground potential differences
between systems.
The
SP3488
features active HIGH and active
LOW common receiver enable controls. Refer
to
SP3488
Truth Table in
Table 1.
The
SP3489
provides independent, active high receiver
enable controls for each pair of receivers. Refer
to
SP3489
Truth Table in
Table 2.
Both devices
feature tri-state outputs and a -7V to +12V
common-mode input range permitting a +7V
ground difference between devices on the
communication bus. The
SP3488
and the
SP3489
are equipped with a fail-safe feature which forces
a logic HIGH at the receiver output when the
input is left floating. The
SP3488
and
SP3489
receivers meet the electrical specifications of
RS-485 and RS-422 serial protocol data rates up
to 10Mbps under load.
AC PARAMETERS
V
CC
= +3.3V±5%; typicals at 25°C; T
AMB
= 25°C unless otherwise noted.
PARAMETER
MIN.
PROPAGATION DELAY
Receiver Input to Output
Low to HIGH (tPLH)
High to LOW (tPH
L
)
Differential Receiver Skew (t
SKD
)
Receiver Rise Time (t
R
)
SP3488
SP3489
Receiver Fall Time (t
F
)
SP3488
SP3489
RECEIVER ENABLE
To Output HIGH
To Output LOW
RECEIVER DISABLE
From Output LOW
From Output HIGH
TYP.
MAX.
UNIT
CONDITIONS
C
L
= 15pF;
Figure 1, 3
75
80
4
7
7
6
6
46
46
115
115
15
15
15
15
100
100
ns
ns
ns
ns
ns
10% to 90%
90% to 10%
ns
ns
ns
ns
C
L
= 15pF;
Figures 2 and 4
(S2 closed)
CL = 15pF;
Figures 2 and 4
(S1 closed)
CL = 15pF;
Figures 2 and 4
(S1 closed)
CL = 15pF;
Figures 2 and 4
(S2 closed)
46
46
100
100
ns
ns
10/16/02
SP3488/3489 Low Power Quad RS-485/422 Line Receivers
© Copyright 2002 Sipex Corporation
5
SIPEX [ SIPEX CORPORATION ]
