EXAR SP485R

SP485R
1/10th Unit Load RS-485 Transceiver
FEATURES
• Allows Over 400 Transceivers On A
Transmission Line (1/10th Unit Load)
• High Impedance on Receiver Inputs
(RIN = 150kΩ typical)
• Half-Duplex Configuration Consistent
With Industry Standard Pinout
• -7V to +12V Common Mode Input
Voltage Range
• Low Power Consumption (250mW)
• Separate Driver and Receiver Enable
DESCRIPTION
The SP485R is a pin-to-pin equivalent to our existing SP485 product and offers a high
receiver input impedance. The higher receiver input impedance allows for connecting over
400 transceivers on a single transmission line without degrading the RS-485 driver signal.
The device is packaged in a 8-pin plastic DIP or 8-pin narrow SOIC.
Figure 1. Typical Application Circuit
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
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.
Power Dissipation
8-pin NSOIC.................................................1000mW
(ØJA = 62ºC/W)
8-pin PDIP....................................................1000mW
(ØJA = 62ºC/W)
VCC.......................................................................+7V
Storage Temperature.......................-65˚C to +150˚C
ELECTRICAL CHARACTERISTICS
Typically 25ºC @ VCC = +5V unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
LOGIC INPUTS
VIL
0.8
VIH
2.0
Volts
Volts
LOGIC OUTPUTS
VOL
0.4
VOH
2.4
Volts
IOUT = -3.2mA
Volts
IOUT = 1.0mA
RS-485 DRIVER DC Characteristics
Open Circuit Voltage
Differential Output Voltage
1.5
Balance
Common-Mode Output
Output Current
6.0
Volts
5.0
Volts
RL = 54Ω, CL = 50pF
+/-0.2
Volts
|VT| - |VT|
3.0
Volts
28.0
Short Circuit Current
+/-250
mA
RL = 54Ω
mA
Terminated in -7V to +12V
RS-485 DRIVER AC Characteristics
Maximum Data Rate
5
Mbps
Output Transition Time
30
Propagation Delay, tPLH
60
Propagation Delay, tPHL
Driver Output Skew
RL = 54Ω,
ns
Rise/fall time, 10% to 90%
100
ns
See Figures 4 & 6, RDIFF = 54Ω,
CL1 = CL2 = 100pF
60
100
ns
See Figures 4 & 6, RDIFF = 54Ω,
CL1 = CL2 = 100pF
5
15
ns
see Figures 4 and 6,
tSKEW = |tDPHL - tDPLH|
0.4
Volts
RS-485 Receiver DC Characteristics
Output Voltage Low, VOL
Output Voltage High, VOH
Tri-State Output Current
2.4
Volts
+/-1
µA
0.4V ≤ VOUT ≤ 2.4V; RE = Vcc
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
ELECTRICAL CHARACTERISTICS
Typically 25ºC @ VCC = +5V unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
+12.0
Volts
+/-0.2
Volts
-7V ≤ VCM ≤ +12V
kΩ
-7V ≤ VCM ≤ +12V
RS-485 RECEIVER DC Characteristics (continued)
Common Mode Range
-7.0
Receiver Sensitivity
Input Impedance
120
150
RS-485 RECEIVER AC Characteristics
Maximum Data Rate
1
Mbps
Propagation Delay; tPHL
1200
ns
See Figures 4 & 8, RDIFF = 54Ω,
CL1 = CL2 = 100pF
Propagation Delay; tPLH
1200
ns
See Figures 4 & 8, RDIFF = 54Ω,
CL1 = CL2 = 100pF
ns
See Figures 4 & 8, RDIFF = 54Ω,
CL1 = CL2 = 100pF,
tSKEW = |tPHL - tPLH|
Differential Receiver Skew
60
RS-485 Driver Enable / Disable Time
Driver Enable to Output Low
40
500
ns
CL = 15pF, see Figures 5 and 7,
S1 closed
Driver Enable to Output High
40
500
ns
CL = 15pF, see Figures 5 and 7,
S2 closed
Driver Disable Time from Low
40
500
ns
CL = 15pF, see Figures 5 and 7,
S1 closed
Driver Disable Time from High
40
500
ns
CL = 15pF, see Figures 5 and 7,
S2 closed
Receiver Enable to Output Low
40
500
ns
CL = 15pF, see Figures 3 and 9,
S1 closed
Receiver Enable to Output High
40
500
ns
CL = 15pF, see Figures 3 and 9,
S2 closed
Receiver Disable from Low
40
500
ns
CL = 15pF, see Figures 3 and 9,
S1 closed
Receiver Disable from High
40
500
ns
CL = 15pF, see Figures 3 and 9,
S1 closed
RS-485 Receiver Enable / Disable Time
POWER REQUIREMENTS
Supply Voltage VCC
+5.25
Volts
Supply Current ICC, No Load
+4.75
300
500
µA
RE = Vcc or 0V, DE = 0V
Supply Current ICC, No Load
500
900
µA
RE = Vcc or 0V, DE = Vcc
+70
ºC
ENVIRONMENTAL
Operating Temperature
Commercial (..C..)
0
Industrial (..E..)
-40
+85
ºC
Storage Temperature
-65
+150
ºC
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
PIN FUNCTION
Pin 1 - RO - Receiver Output
Pin 2 - RE - Receiver Output Enable Active LOW
Pin 3 - DE - Driver Output Enable Active HIGH
Pin 4 DI - Driver Input
Pin 5 - GND - Ground Connection
Pin 6 - A - Driver Output / Receiver input
Non-Inverting
Pin 7 - B - Driver Output / Receiver Input Inverting
Pin 8 - Vcc - Positive Supply 4.75V ≤ Vcc ≤ 5.25V
Receiver input graph
Standard SP485 Reciever
SP485R Reciever
+1.0mA
-7V
+100µA
-7V
-3V
+12V
+6V
-0.6mA
-3V
+6V
-60µA
1 Unit Load
Maximum Input Current
versus voltage.
(Shaded region)
+12V
1/10 Unit Load
Maximum Input Current
versus voltage.
(Shaded region)
Test Circuits
A
R
VOD
R
1kΩ
S2
B
Figure 2. Driver DC Test Load Circuit
DI
A
B
VCC
S1
CRL
VOC
1kΩ
Test Point
Receiver
Output
CL1
RL
CL2
A
B
Figure 3. Receiver Timing Test Load Circuit
Output
Under
Test
RO
15pF
500Ω
S1
VCC
CL
S2
Figure 4. RS-485 Driver/Receiver Timing Test
Figure 5. Driver Timing Test Load #2 Circuit
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
SWITCHING WAVEFORMS
DRIVER INPUT
f ≥ 1MHz; t R ≤ 10ns; t F ≤ 10ns
+3V
1.5V
0V
DRIVER
OUTPUT
1.5V
t PLH
B
t PHL
VO 1/2VO
A
1/2VO
t DPLH
DIFFERENTIAL VO+
0V
OUTPUT
VA – VB VO–
t DPHL
tF
tR
t SKEW = |t DPLH - t DPHL |
Figure 6. Driver Propagation Delays
DE
A, B
A, B
f = 1MHz; t R < 10ns; t F < 10ns
+3V
1.5V
0V
1.5V
t ZL
5V
2.3V
VOL
VOH
2.3V
0V
t LZ
Output normally LOW
0.5V
Output normally HIGH
0.5V
t ZH
t HZ
Figure 7. Driver Enable and Disable Times
A– B
f = 1MHz; t R ≤ 10ns ; t F ≤ 10ns
VOD2 +
0V
VOD2 –
RECEIVER OUT
VOH
VOL
0V
INPUT
1.5V
1.5V
OUTPUT
t PHL
t PLH
Figure 8. Receiver Propagation Delays
RE
+3V
RECEIVER OUT
0V
5V
VIL
1.5V f = 1MHz; t ≤ 10ns; t ≤ 10ns
R
F
t ZL
1.5V
VIH
RECEIVER OUT
0V
1.5V
1.5V
t LZ
Output normally LOW
0.5V
Output normally HIGH
0.5V
t ZH
t HZ
Figure 9. Receiver Enable and Disable Times
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
DESCRIPTION
transceivers with an input impedance of at
least 120kΩ in parallel along with the two
125Ω cable termination resistors on each
end.
The SP485R is a low power RS-485 differential transceiver. Similar to the SP485,
the SP485R contains a half-duplex driver
and receiver with tri-state control. However,
the SP485R is intended for increased connections on a single bus compared to the
original RS-485 specifcation.
The receiver contains an enable pin (RE)
which enables the receiver when a logic LOW
is asserted. A logic HIGH will tri-state the
receiver output and the inputs will maintain
at least 120kΩ impedance. The reciever can
operate to at least 1Mbps
The RS-485 standard is ideal for multi-drop
applications where one bus can contain
many drivers and/or receivers.The RS-485
standard implementation allows up to 32
transceivers to be connected on to the data
bus. RS-485 is also specified for driving
higher speeds over long cable lengths of
up to 4000 feet. The SP485R exceeds the
standard by allowing up to 400 receivers to
share the bus
The receiver also contains a fail-safe
feature which outputs a logic HIGH when
the inputs are open as in a disconnected
cable.
Drivers
The driver output complies with the RS485 electrical characteristics as specified
by the standard. The output swings from
0V to Vcc and maintains greater than +1.5V
with a 54Ω load attached between the two
outputs. In adhering to the RS-485 specification, the driver outputs inherently comply
with the RS-422 standard. With a load of
100Ω between the two outputs, the driver
can sustain at least +2.0V.
The driver contains an enable pin (DE) which
tri-states the output when DE is logic LOW.
The outputs during the tri-state condition are
at high impedance (>100kΩ). A logic HIGH
enables the driver for normal operation. The
driver can operate to at least 5Mbps.
Receivers
The SP485R receiver has differential inputs with an input sensitivity of lower than
±200mV. As mentioned above, the RS-485
specification allows up to 32 transceivers on
the same bus. The SP485R allows over 400
transceivers on the same bus due to its high
impedance of at least 120kΩ. This higher
capacity allows more components to be attached to the same bus without degrading
the signal quality. The drivers are still able to
drive an equivalent 54Ω from the 320
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309
ORDERING INFORMATION
Model
Temperature Range
Package Types
SP485RCN-L........................................................................ 0°C to +70°C.................................................................................................8-pin NSOIC
SP485RCN-L/TR.................................................................. 0°C to +70°C.................................................................................................8-pin NSOIC
SP485RCP-L....................................................................... 0°C to +70°C................................................................................................8-pin PDIP
SP485REN-L...................................................................... -40°C to +85°C..............................................................................................8-pin NSOIC
SP485REN-L/TR................................................................ -40°C to +85°C..............................................................................................8-pin NSOIC
SP485REP-L...................................................................... -40°C to +85°C..............................................................................................8-pin PDIP
Note: /TR = Tape and Reel
revision history
DATE
REVISION
06/21/04
--
07/23/09
1.0.0
DESCRIPTION
Legacy Sipex Datasheet
Convert to Exar Format. Update ordering information as a result of discontinued
Lead type package options per PDN 081126-01. Remove all reference to the discontinued SP481R.
Notice
EXAR Corporation reserves the right to make changes to any products contained in this publication in order to improve design, performance or reliability. EXAR Corporation assumes no representation that the circuits are free of patent infringement. Charts and schedules contained herein are only for
illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked;
no responsibility, however, is assumed for inaccuracies.
EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can
reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for
use in such applications unless EXAR Corporation receives, in writting, assurances to its satisfaction that: (a) the risk of injury or damage has been
minimized ; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances.
Copyright 2009 EXAR Corporation
Datasheet July 2009
Send your Interface technical inquiry with technical details to: [email protected]
Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
SP485R_100_072309