10/15/02
SP3486/3487 Low Power Quad RS485/422 Line Drivers
5
Copyright 2002 Sipex Corporation
AC PARAMETERS
V
CC
= +3.3V
±
5%; typicals at 25
°
C; T
AMB
= 25
°
C unless otherwise noted.
PARAMETER
PROPAGATION DELAY
Driver Input to Output
MIN.
TYP.
MAX.
UNIT
CONDITIONS
Figure 2 and 5
Low to High (t
PLH
)
High to Low (t
)
Differential Driver Skew
20
20
40
40
5
60
60
10
ns
ns
ns
| t
(Y) - t
(Y) |, | t
PHL
(Z) - t
PLH
(Z) | ,
Figures 2 and 5
10% to 90% R
DIFF
= 60
Driver Rise Time (t
R
)
SP3486
SP3487
Driver Fall Time (t
F
)
SP3486
SP3487
DRIVER ENABLE
To Output High
10
10
ns
ns
90% to 10% R
DIFF
= 60
10
10
ns
ns
110
ns
Figures 3 and 6
To Output Low
110
ns
Figures 4 and 6
DRIVER DISABLE
From Output Low
110
ns
Figures 4 and 6
From Output High
110
ns
Figures 3 and 6
FEATURES
The
SP3486
and the
SP3487
are +3.3V low power
quad line drivers that meet the specifications of
the RS-485 and RS-422 serial protocols. These
devices are pin-to-pin compatible with Sipex's
SP486 and SP487 devices as well as popular
industry standards. The
SP3486
and
SP3487
devices feature Sipex's BiCMOS process
allowing low power operation without sacrificing
performance.
The RS-485 standard is ideal for multi-drop
applications or for long distance interfaces.
RS-485 allows up to 32 drivers and 32 receivers
to be connected to a data bus, making it an ideal
choice for multi-drop applications. Since the
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. Data is virtually
immune to noise in the transmission line because
the RS-485 protocol is a differential interface.
Driver
The drivers for both the
SP3486
and
SP3487
have differential outputs. The typical voltage
output swing with no load will be 0V to +5V.
With worst case loading of 54
across the
differential outputs, the driver can maintain
greater than +1.5V voltage levels.
The drivers of the
SP3486
feature active HIGH
and active LOW common driver enable
controls. Refer to
SP3486
Truth Table in Table
1. The
SP3487
provides independent, active
high driver enable controls for each pair of
drivers. Refer to
SP3487
Truth Table in Table 2.
The driver outputs are short-circuit limited
to 250mA. The
SP3486
and
SP3487
drivers
meet the electrical specifications of RS-485
and RS-422 serial protocols up to 10Mbps
under load.