SP1490E/SP1491E
Full Duplex RS-485 Transceivers
fEaturES
■ +5V Only
■ Low Power BiCMOS
■ Driver/Receiver Enable (SP1491E)
■ RS-485 and RS-422 Drivers/Receivers
■ Pin Compatible with SN75179 (SP1490E)
■ Pin Compatible with SN75180 (SP1491E)
■ Improved ESD Specifications
±15kV Human Body Model
±15kV IEC1000-4-2 Air Discharge
±8kV IEC1000-4-2 Contact Discharge
VCC
1
RO
2
DI
3
GND
4
8
A
7
B
6
Z
5
Y
SP1490E
8 Pin
-
nSOIC
8 Pin nSOIC
aPPLicationS
■ Industial Networks
■ Motor Control
■ Telecom
■ HVAC/ Building Control
dEScriPtion
The SP1490E is a low power differential line driver/receiver meeting RS-485 and RS-422 standards
up to 20Mbps. The SP1491E is identical to the SP1490E with the addition of driver and receiver tri-
state enable lines. Both products feature ±200mV receiver input sensitivity, over wide common mode
range. The SP1490E is available in an 8-pin NSOIC packages for operation over the commercial and
industrial temperature ranges. The SP1491E is available in a 14-pin NSOIC packages for operation
over the commercial and industrial temperature ranges.
BLocK diaGraM
Vcc 1
RO 2
NC 1
8 A
RO 2
RE B 3
DE 4
DI 5
GND 6
GND 7
14 Vcc
13 NC
12 A
R
7 B
6 Z
R
11 B
DI 3
GND 4
D
5 Y
10 Z
D
9 Y
8 NC
SP1490E
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP1491E
SP1490_SP1491E_100_061209
1
aBSoLutE MaXiMuM ratinGS
These are stress ratings only and functional operation of the device at
these ratings or any other above those indicated in the operation sections
of the specifications below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may affect reliability.
V
CC
...................................................................................................+7V
Input Voltages
Drivers................................................-0.5V to (V
CC
+0.5V)
Receivers..................................................................±14V
Output Voltages
Drivers......................................................................±14V
Receivers...........................................-0.5V to (V
CC
+0.5V)
Storage Temperature....................................................-65˚C to +150˚
Power Dissipation.....................................................................1000mW
ELECTRICAL CHARACTERISTICS
T
MIN
to T
MAX
and V
CC
= 5V ± 5% unless otherwise noted.
ParaMEtErS
SP1490E/1491E drivEr
DC Characteristics
Differential Output Voltage
Differential Output Voltage
Differential Output Voltage
figure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary States
Driver Common-Mode
Output Voltage
Input High Voltage
Input Low Voltage
Input Current
Driver Short-Circuit Current
V
OUT
= HIGH
V
OUT
= LOW
SP1490E/1491E drivEr
ac characteristics
Maximum Data Rate
Driver Input to Output
Driver Input to Output
Driver Skew
Driver Rise or Fall Time
SP1491E only
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
Min.
3.5
2
1.5
tYP.
MaX.
V
CC
V
CC
V
CC
unitS
Volts
Volts
Volts
conditionS
Unloaded; R = ∞ ; see figure 1
With Load; R = 50Ω; (RS422);
see figure 1
With Load; R = 27Ω; (RS485); see
0.2
2.0
3
0.8
±10
±250
±250
Volts
Volts
Volts
Volts
μA
mA
mA
R = 27Ω or R = 50Ω; see figure 1
R = 27Ω or R = 50Ω; see figure 1
Applies to D
Applies to D
Applies to D
-7V ≤ V
O
≤ +12V
-7V ≤ V
O
≤ +12V
20
30
30
40
40
5
Mbps
ns
ns
ns
ns
8
20
t
R/F
; R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF;
see figures 3 and 6
t
R/F
; R
DIFF
= 54Ω, C
L1
= C
L2
= 100pF;
see figures 3 and 6
see figures 3 and 6,
t
R/F
= | t
PLH
- t
PHL
|
From 10% to 90%; R
DIFF
= 54Ω,
C
L1
= C
L2
= 100pF; see figures 3 and 6
t
R/F
C
L1
= C
L2
= 100pF; see figures
4 and 7; S
2
closed
C
L1
= C
L2
= 100pF; see figures
4 and 7; S
1
closed
C
L1
= C
L2
= 100pF; see figures
4 and 7; S
1
closed
C
L1
= C
L2
= 100pF; see figures
4 and 7; S
2
closed
20
40
40
40
70
70
70
70
ns
ns
ns
ns
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP1490_SP1491E_100_061209
2
T
MIN
to T
MAX
and V
CC
= 5V ± 5% unless otherwise noted.
SPEcificationS
(continued)
SP1490E/1491E rEcEivEr
dc characteristics
Differential Input Threshold
Input Hysteresis
Output Voltage High
Output Voltage Low
Input Resistance
Input Current (A, B); V
IN
= 12V
Input Current (A, B); V
IN
= -7V
Short-Circuit Current
0.2
3.5
12
70
15
+0.2
0.4
±1.0
-0.8
85
Volts
mV
Volts
Volts
kΩ
mA
mA
mA
-7V ≤ V
CM
≤ 12V
V
CM
= 0V
I
O
= -4mA, V
ID
= +200mV
I
O
= +4mA, V
ID
= -200mV
-7V ≤ V
CM
≤ 12V (1 unit load)
V
IN
= 12V
V
IN
= -7V
0V ≤ V
O
≤ V
CC
ParaMEtErS
SP1490E/1491E rEcEivEr
ac characteristics
Maximum Data Rate
Receiver Input to Output
Receiver Input to Output
Diff. Receiver Skew It
PLH
-t
PHL
I
Receiver Tplh/Tphl
PoWEr rEQuirEMEntS
Supply Voltage
Supply Current
EnvironMEntaL and
MEchanicaL
Operating Temperature
Commercial (_C_)
Industrial (_E_)
Storage Temperature
Min.
tYP.
MaX.
unitS
conditionS
20
20
20
45
45
5
40
50
50
10
70
+5.25
Mbps
ns
ns
ns
ns
Volts
μA
t
PLH
; R
DIFF
= 54Ω,
C
L1
= C
L2
=
100pF;
Figures 3 & 8
t
PHL
; R
DIFF
= 54Ω,
C
L1
= C
L2
=
100pF;
Figures 3 & 8
R
DIFF
= 54Ω; C
L1
= C
L2
= 100pF;
+4.75
900
0
-40
-65
+70
+85
+150
°C
°C
°C
A
R
V
OD
R
B
V
OC
Receiver
Output
C
RL
Test Point
S
1
1K
S
2
1K
V
CC
Figure 1. Driver DC Test Load Circuit
3V
DE
DI
A
B
R
DIFF
C
L2
C
L1
Figure 2. Receiver Timing Test Load Circuit
A
B
RO
15pF
Output
Under
Test
500
C
L
S
1
V
CC
S
2
Figure 3. Driver/Receiver Timing Test Circuit
Figure 4. Driver Timing Test Load #2 Circuit
SP1490_SP1491E_100_061209
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
3
DI
DRIVER
OUTPUT
+3V
0V
B
A
f = 1MHz; t
R
< 10ns; t
F
< 10ns
1.5V
t
PLH
V
O
1/2V
O
t
SKEW
t
PHL
1.5V
t
PLH
1/2V
O
t
SKEW
DIFFERENTIAL V
O
+
OUTPUT 0V
V
A
– V
B
V
O
–
t
R
t
F
Figure 6. Driver Propagation Delays
DE
+3V
0V
5V
V
OL
V
OH
0V
f = 1MHz; t
R
< 10ns; t
F
< 10ns
1.5V
t
ZL
2.3V
Output normally LOW
Output normally HIGH
1.5V
t
LZ
0.5V
0.5V
t
HZ
A, B
A, B
2.3V
t
ZH
Figure 7. Driver Enable and Disable Times SP1491E only
A–B
V
0D2
+
V
0D2
–
V
OH
V
OL
t
PHL
0V
f = 1MHz; t
R
≤
10ns; t
F
≤
10ns
INPUT
1.5V
0V
R
OUTPUT
1.5V
t
PHL
Figure 8. Receiver Propagation Delays
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP1490_SP1491E_100_061209
4
dEtaiLEd dEScriPtion
The SP1490E and SP1491E are full-duplex dif-
ferential transceivers that meet the requirements
of RS-485 and RS-422. Fabricated with a Exar
proprietary BiCMOS process, both products
require a fraction of the power of older bipolar
designs.
The RS-485 standard is ideal for multi-drop
applications or for long-distance interfaces.
RS-485 allows up to 32 drivers and 32 receiv-
ers 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 accom-
modate ground potential differences. Because
RS-485 is a differential interface, data is virtually
immune to noise in the transmission line.
driver...
The drivers for both the SP1490E and SP1491E
have differential outputs. The typical voltage
output swing with no load will be 0 volts to +5
volts. With worst case loading of 54Ω across
the differential outputs, the driver can maintain
greater than 1.5V voltage levels.
The driver of the SP1491E has a driver enable
control line which is active high. A logic high
on DE (pin 4) of the SP1491E will enable
the differential driver outputs.
A logic low on DE (pin 4) of the SP1491E will
tri-state the driver outputs. The SP1490E does
not have a driver enable.
receiver...
The receivers for both the SP1490E and SP1491E
have differential inputs with an input sensitiv-
ity as low as ±200mV. 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 receivers for both the
SP1490E and SP1491E are equipped with
the fail-safe feature. Fail-safe guarantees that
the receiver output will be in a high state when
the input is left unconnected and floating.
The receiver of the SP1491E has a receiver
enable control line which is active low. A logic
low on REB (pin 3) of the SP1491E will enable
the differential receiver. A logic high on REB
(pin 3) of the SP1491E will tri-state the re-
ceiver.
INPUTS
RE
SP1491E
only
OUTPUTS
INPUTS
DE
SP1491E only
1
1
0
DI
1
0
x
OUTPUTS
Y
1
0
z
Z
0
1
z
A-B
+0.2V
-0.2V
open
x
R
1
0
1
z
0
0
0
1
Recieve Function Truth Table
Transmit Function Truth Table
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP1490_SP1491E_100_061209
5
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