10/15/02

SP3486/3487 Low Power Quad RS485/422 Line Drivers

© Copyright 2002 Sipex Corporation

5

AC PARAMETERS

V

PARAMETER

MIN.

TYP.

MAX.

UNIT

CONDITIONS

PROPAGATION DELAY

Driver Input to Output

Figure 2 and 5

Low to High (t

4060

ns

High to Low (t

4060

ns

Differential Driver Skew

5

10

ns

| t

Figures 2 and 5

Driver Rise Time (t

10% to 90% R

SP3486

10

ns

SP3487

10

ns

Driver Fall Time (t

90% to 10% R

SP3486

10

ns

SP3487

10

ns

DRIVER ENABLE

To Output High

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

Ω 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.