SP490 / SP491
Full-Duplex RS-485 Transceivers
Description
FEATURES
■■ 5V only
■■ Low power BiCMOS
■■ Driver/receiver enable (SP491)
■■ RS-485 and RS-422 drivers/receivers
■■ Pin compatible with LTC490 and SN75179
(SP490)
■■ Pin compatible with LTC491 and
SN75180 (SP491)
The SP490 is a low power differential line driver/receiver meeting
RS-485 and RS-422 standards up to 5Mbps. The SP491 is identical
to the SP490 with the addition of driver and receiver tri-state enable
lines. Both products feature ±200mV receiver input sensitivity, over
wide common mode range. The SP490 is available in 8-pin NSOIC
packages for operation over the commercial temperature range. The
SP491 is available in 14-pin NSOIC packages for operation over the
commercial and industrial temperature ranges.
Ordering Information - Back Page
Block Diagrams
VCC
R
D
GND
1
NC
2
3
R
8 A
7 B
6
D
4
R
1
2
R
3
REB
DE 4
Z
D
5 Y
GND
GND
SP490
5
6
7
14 VCC
13 NC
12 A
11 B
10
D
Z
9 Y
8
NC
SP491
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1/13
SP490 / SP491
Absolute Maximum Ratings (SP490)
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.
VCC................................................................................7.0V
Input Voltages
Drivers........................-0.5V to (VCC+0.5V)
Receivers...........................................±14V
Output Voltages
Drivers................................................±14V
Receivers....................-0.5V to (VCC+0.5V)
Storage Temperature.................................-65˚C to +150˚C
Power Dissipation..................................................1000mW
Electrical Characteristics
TAMB = TMIN to TMAX and VCC = 5V ±5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
VCC
V
Unloaded; R = ∞Ω ; Figure 1
SP490 Driver DC Characteristics
Differential output voltage
Differential output voltage
2
VCC
V
With load; R = 50Ω (RS-422); Figure 1
Differential output voltage
1.5
VCC
V
With load; R = 27Ω (RS-485); Figure 1
0.2
V
R = 27Ω or R = 50Ω; Figure 1
3
V
R = 27Ω or R = 50Ω; Figure 1
V
Applies to D
Change in magnitude of driver
differential output voltage for
complimentary states
Driver common-mode output voltage
Input high voltage
2.0
Input low voltage
0.8
V
Applies to D
Input current
±10
µA
Applies to D
Driver short circuit current
VOUT = HIGH
±250
mA
-7V ≤ VO ≤ 12V
Driver short circuit current
VOUT = LOW
±250
mA
-7V ≤ VO ≤ 12V
SP490 Driver AC Characteristics
Maximum data rate
5
Mbps
Driver input to output, tPLH
30
60
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 5
Driver input to output, tPHL
30
60
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 5
Driver skew
5
ns
tSKEW = | tDPLH - tDPHL |; Figures 3 & 5
Driver rise or fall time
15
ns
From 10% to 90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; Figures 3 & 5
40
REV 1.0.2
2/13
SP490 / SP491
Electrical Characteristics (Continued)
TAMB =TMIN to TMAX and VCC = 5V ±5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
0.2
V
CONDITIONS
SP490 Receiver DC Characteristics
Differential input threshold
-0.2
Input hysteresis
Output voltage HIGH
70
3.5
Output voltage LOW
Input resistance
mV
0.4
12
15
-7V ≤ VCM ≤ 12V
VCM = 0V
V
VID = 200mV, IO = -4mA
V
VID = -200mV, IO = 4mA
kΩ
-7V ≤ VCM ≤ 12V
Input current (A, B); VIN = 12V
±1.0
mA
VIN = 12V
Input current (A, B); VIN = -7V
-0.8
mA
VIN = -7V
85
mA
0V ≤ VO ≤ VCC
Short circuit current
SP490 Receiver AC Characteristics
Maximum data rate
5
Mbps
Receiver input to output, tPLH
45
150
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF;
Figures 3 and 7
Receiver input to output, tPHL
45
150
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF;
Figures 3 and 7
Differential receiver skew, |tPLH- tPHL|
13
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF;
Figures 3 and 7
Power Requirements
Supply Voltage
4.75
Supply Current
5.25
900
V
µA
SP490 Environmental and Mechanical
Operating Temperture
Commercial (_C_)
0
70
°C
Storage Temperature
-65
150
°C
Package
NSOIC (_N)
REV 1.0.2
3/13
SP490 / SP491
Test Circuits
A
VOD
R
VCC
S1
CRL
VOC
1kΩ
Test Point
Receiver
Output
R
1kΩ
S2
B
Figure 1: Driver DC Test Load Circuit
Figure 2: Receiver Timing Test Load Circuit
3V
DE
DI
CL1
D
RDIFF
R
RO
CL2
15pF
Output
Under
Test
500Ω
S1
VCC
CL
S2
Figure 3: Driver/Receiver Timing Test Circuit
Figure 4: Driver Timing Test Load #2 Circuit
REV 1.0.2
4/13
SP490 / SP491
Switching Waveforms
DI
DRIVER
OUTPUT
VDIFF
VZ – VY
f = 1MHz; t R ≤ 10ns; t F ≤ 10ns
+3V
1.5V
0V
Z
Y
1.5V
t PLH
t PHL
VO 1/2VO
1/2VO
t DPLH
VO+
0V
VO–
t DPHL
tF
tR
t SKEW = |t DPLH - t DPHL|
Figure 5: Driver Propagation Delays
f = 1MHz; t R ≤ 10ns; t F ≤ 10ns
DE
Y, Z
3V
1.5V
0V
1.5V
t ZL
2.3V
VOL
VOH
Y, Z
t LZ
2.3V
0V
Output normally LOW
0.5V
Output normally HIGH
0.5V
t ZH
t HZ
Figure 6: Driver Enable and Disable Times
A– B
R
f = 1MHz; t R ≤ 10ns ; t F ≤ 10ns
VOD2 +
0V
VOD2 –
VOH
VOL
1.5V
t PHL
0V
INPUT
1.5V
OUTPUT
t PLH
t SKEW = |t DPLH - t DPHL|
Figure 7: Receiver Propagation Delays
REV 1.0.2
5/13
SP490 / SP491
Absolute Maximum Ratings (SP491)
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.
VCC................................................................................7.0V
Input Voltages
Logic...........................-0.5V to (VCC+0.5V)
Drivers........................-0.5V to (VCC+0.5V)
Receivers...........................................±14V
Output Voltages
Logic...........................-0.5V to (VCC+0.5V)
Drivers................................................±14V
Receivers....................-0.5V to (VCC+0.5V)
Storage Temperature.................................-65˚C to +150˚C
Power Dissipation..................................................1000mW
Electrical Characteristics
TAMB = TMIN to TMAX and VCC = 5V ±5% unless otherwise noted
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
VCC
V
Unloaded; R = ∞Ω ; Figure 1
SP491 Driver DC Characteristics
Differential output voltage
Differential output voltage
2
VCC
V
With load; R = 50Ω (RS-422); Figure 1
Differential output voltage
1.5
VCC
V
With load; R = 27Ω (RS-485); Figure 1
0.2
V
R = 27Ω or R = 50Ω; Figure 1
3
V
R = 27Ω or R = 50Ω; Figure 1
V
Applies to DE, D, REB
Change in magnitude of driver
differential output voltage for
complimentary states
Driver common-mode output voltage
Input high voltage
2.0
Input low voltage
0.8
V
Applies to DE, D, REB
Input current
±10
µA
Applies to DE, D, REB
Driver short circuit current
VOUT = HIGH
±250
mA
-7V ≤ VO ≤ 12V
Driver short circuit current
VOUT = LOW
±250
mA
-7V ≤ VO ≤ 12V
REV 1.0.2
6/13
SP490 / SP491
Electrical Characteristics, Continued
TAMB = TMIN to TMAX and VCC = 5V ±5% unless otherwise noted
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
SP491 Driver AC Characteristics
Maximum data rate
5
Mbps
REB = 5V, DE = 5V
Driver input to output, tPLH
30
60
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 5
Driver input to output, tPHL
30
60
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 5
Driver skew
5
10
ns
tSKEW = | tDPLH - tDPHL |; Figures 3 & 5
Driver rise or fall time
15
40
ns
From 10%-90%; RDIFF = 54Ω,
CL1 = CL2 = 100pF; Figures 3 & 5
Driver enable to output HIGH
40
70
ns
CL1 = CL2 = 100pF; Figures 4 & 6, S2 closed
Driver enable to output LOW
40
70
ns
CL1 = CL2 = 100pF; Figures 4 & 6, S1 closed
Driver disable time from LOW
40
70
ns
CL1 = CL2 = 100pF; Figures 4 & 6, S1 closed
Driver disable time from HIGH
40
70
ns
CL1 = CL2 = 100pF; Figures 4 & 6, S2 closed
0.2
Volts
SP491 Receiver DC Characteristics
Differential input threshold
-0.2
Input hysteresis
Output voltage HIGH
70
mV
3.5
-7V ≤ VCM ≤ 12V
VCM = 0V
Volts
VID = 200mV, IO = -4mA
VID = -200mV, IO = 4mA
Output voltage LOW
0.4
Volts
Three-State ( High Impedance)
Output Current
±1
µA
0.4V ≤ VO ≤ 2.4V; REB = 5V
kΩ
-7V ≤ VCM ≤ 12V
Input resistance
12
15
Input current (A, B); VIN = 12V
±1.0
mA
DE = 0V, VCC = 0V or 5.25V, VIN = 12V
Input current (A, B); VIN = -7V
-0.8
mA
DE = 0V, VCC = 0V or 5.25V, VIN = -7V
85
mA
0V ≤ VO ≤ VCC
Short circuit current
SP491 Receiver AC Characteristics
Maximum data rate
5
Mbps
REB = 0V
Receiver input to output, tPLH
20
45
150
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 7
Receiver input to output, tPHL
20
45
150
ns
RDIFF = 54Ω, CL1 = CL2 = 100pF; Figures 3 & 7
ns
|tPLH - tPHL|; RDIFF = 54Ω, CL1 = CL2 = 100pF;
Figures 3 & 7
Differential receiver skew
13
Receiver enable to output LOW
45
70
ns
CRL = 15pF; Figures 2 & 8; S1 closed
Receiver enable to output HIGH
45
70
ns
CRL = 15pF; Figures 2 & 8; S2 closed
Receiver disable time from LOW
45
70
ns
CRL = 15pF; Figures 2 & 8; S1 closed
Receiver disable time from HIGH
45
70
ns
CRL = 15pF; Figures 2 & 8; S2 closed
REV 1.0.2
7/13
SP490 / SP491
Electrical Characteristics, Continued
TAMB = TMIN to TMAX and VCC = 5V ±5% unless otherwise noted
PARAMETERS
MIN.
TYP.
MAX.
UNITS
5.25
V
CONDITIONS
Power Requirements
Supply voltage
4.75
Supply current
900
µA
REB, D = 0V or VCC; DE = VCC
SP491 Environmental and Mechanical
Operating Temperture
Commercial (_C_)
Industrial (_E_)
Storage Temperature
0
70
°C
-40
85
°C
-65
150
°C
Package
NSOIC (_N)
Switching Waveforms
f = 1MHz; t R ≤ 10ns; t F ≤ 10ns
REB
R
3V
0V
5V
VIL
1.5V
1.5V
t ZL
1.5V
VIH
R
0V
1.5V
t LZ
Output normally LOW
0.5V
Output normally HIGH
0.5V
t ZH
t HZ
Figure 8: Receiver Enable and Disable Times
REV 1.0.2
8/13
SP490 / SP491
Pin Functions
VCC
R
D
1
Pin Number
2
3
R
6
D
4
GND
8 A
7 B
Z
5 Y
Pin Name
Description
1
VCC
Positive supply
2
R
Receiver output
3
D
Driver Input
4
GND
Ground connection
5
Y
Non-inverting driver output
6
Z
Inverting driver output
7
B
Inverting receiver Input
8
A
Non-inverting receiver input
SP490
Pinout (Top View)
NC
R
1
2
R
3
REB
DE 4
D
GND
GND
5
6
7
14 VCC
13 NC
12 A
11 B
10
D
Pin Number
Z
9 Y
8
NC
SP491
Pinout (Top View)
REV 1.0.2
Pin Name
Description
1
NC
No connect
2
R
Receiver output
3
REB
Receiver output enable active LOW
4
DE
Driver output enable active HIGH
5
D
Driver input
6
GND
Ground connection
7
GND
Ground connection
8
NC
No connect
9
Y
Non-inverting driver output
10
Z
Inverting driver output
11
B
Inverting receiver input
12
A
Non-Inverting receiver input
13
NC
No connect
14
VCC
Positive supply
9/13
SP490 / SP491
Description
The SP490 and SP491 are full-duplex differential
transceivers that meet the requirements of RS-485 and
RS-422. Fabricated with a MaxLinear 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 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 accommodate ground potential differences.
Because RS-485 is a differential interface, data is virtually
immune to noise in the transmission line.
Receivers
The receivers for both the SP490 and SP491 have
differential inputs with an input sensitivity 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 SP490 and SP491 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.
The receiver of the SP491 has a receiver enable control line
which is active low. A logic low on REB (pin 3) of the SP491
will enable the differential receiver. A logic high on REB
(pin 3) of the SP491 will tri-state the receiver.
Drivers
The drivers for both the SP490 and SP491 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 SP491 has a driver enable control line which
is active high. A logic high on DE (pin 4) of the SP491 will
enable the differential driver outputs. A logic low on DE (pin
4) of the SP491 will tri-state the driver outputs. The SP490
does not have a driver enable.
REV 1.0.2
10/13
SP490 / SP491
Mechanical Dimensions
NSOIC8
Top View
Front View
Side View
Drawing No:
Revision:
REV 1.0.2
POD-00000108
A
11/13
SP490 / SP491
Mechanical Dimensions
NSOIC14
Top View
Front View
Side View
Drawing No: POD-00000109
Revision:
REV 1.0.2
A
12/13
SP490 / SP491
Ordering Information(1)
Part Number
Operating Temperature Range
SP490CN-L/TR
0°C to 70°C
SP491CN-L/TR
SP491EN-L/TR
Lead-Free
Yes
Package
Packaging Method
8-pin NSOIC
Reel
(2)
-40°C to 85°C
14-pin NSOIC
Reel
Reel
NOTE:
1. Refer to www.exar.com/SP490 and www.exar.com/SP491 for most up-to-date Ordering Information.
2. Visit www.exar.com for additional information on Environmental Rating.
Revision History
Revision
Date
Description
-
02/24/05
Sipex Legacy Data Sheet
1.0.0
07/14/08
Convert to Exar format.
1.0.1
June 2011
Remove minimum entry to Driver Short Circuit Current. Change SP490 receiver propagation
typical to 45ns. Remove SP491 receiver short circuit current minimum entry. Change SP491
receiver propagation delay MIN and TYP levels to 20 and 45ns respectively. Change SP491
receiver Enable and Disable time TYP and MAX levels to 45 and 70ns respectively. Change
SP491 Supply Current TYP to 900µA. Remove SP491 driver rise/fall time minimum. Update
ordering information.
02/06/18
Updated format and included MaxLinear logo. Remove GND from Differential Output Voltage
min (page 2 & 6). Update ordering information table format. Corrected Figure numbers (after
Figure 4). Added Pin Function section. Corrected SP491 pin 3 name. Removed obsolete
PDIP reference in description and mechanical section, and industrial for SP490.
1.0.2
Corporate Headquarters:
5966 La Place Court
Suite 100
Carlsbad, CA 92008
Tel.:+1 (760) 692-0711
Fax: +1 (760) 444-8598
www.maxlinear.com
High Performance Analog:
1060 Rincon Circle
San Jose, CA 95131
Tel.: +1 (669) 265-6100
Fax: +1 (669) 265-6101
Email: serialtechsupport@exar.com
www.exar.com
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