1
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2002 Sipex Corporation
SP3481/SP3485
RS-485 and RS-422 Transceivers
Operates from a single +3.3V supply
Interoperable with +5.0V logic
Driver/Receiver Enable
Low Power Shutdown Mode (SP3481)
-7V to +12V Common-Mode Input
Voltage Range
Allows up to 32 transceivers on
the serial bus
Compatibility with the industry
standard 75176 pinout
Driver Output Short-Circuit Protection
8
7
6
5
1
2
3
4
Vcc
B
A
GND
D
R
RO
RE
DE
DI
SP3481 and SP3485
RE
DESCRIPTION
The SP3481 and the SP3485 are a family of +3.3V low power half-duplex transceivers that
meet the specifications of the RS-485 and RS-422 serial protocols. These devices are pin-to-
pin compatible with the Sipex SP481, SP483, and SP485 devices as well as popular industry
standards. The SP3481 and the SP3485 feature Sipex's BiCMOS process, allowing low power
operation without sacrificing performance. The SP3481 and SP3485 meet the electrical
specifications of RS-485 and RS-422 serial protocols up to 10Mbps under load. The SP3481
is equipped with a low power Shutdown mode.
+3.3V Low Power Half-Duplex RS-485
Transceivers with 10Mbps Data Rate
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2000 Sipex Corporation
2
SPECIFICATIONS
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V
5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
SP3481/SP3485 DRIVER
DC Characteristics
Differential Output Voltage
GND
V
CC
Volts
Unloaded; R =
;
Figure 1
Differential Output Voltage
2
V
CC
Volts
with load; R = 50
; (RS-422);
Figure 1
Differential Output Voltage
1.5
V
CC
Volts
with load; R = 27
; (RS-485);
Figure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary States
0.2
Volts
R = 27
or R = 50
;
Figure 1
Driver Common-Mode
Output Voltage
3
Volts
R = 27
or R = 50
;
Figure 1
Input High Voltage
2.0
Volts
Applies to DE, DI, RE
Input Low Voltage
0.8
Volts
Applies to DE, DI, RE
Input Current
10
A
Applies to DE, DI, RE
Driver Short-Circuit Current
V
OUT
= HIGH
250
mA
-7V
V
O
+12V
V
OUT
= LOW
250
mA
-7V
V
O
+12V
SP3481/SP3485 DRIVER
AC Characteristics
Maximum Data Rate
10
Mbps
RE = V
CC
, DE = V
CC
Driver Input to Output, t
PLH
20
40
60
ns
Figures 2 and 8
Driver Input to Output, t
PHL
20
40
60
ns
Figures 2 and 8
Differential Driver Skew
2
10
ns
t
DO1
- t
DO2
Figures 2 and 9
Driver Rise or Fall Time
5
20
ns
From 10% to 90% ;
Figures 3 and
9
Driver Enable to Output High
52
120
ns
Figures 4 and 10
Driver Enable to Output Low
60
120
ns
Figures 5 and 10
Driver Disable Time from Low
40
120
ns
Figures 5 and 10
Driver Disable Time from High
60
120
ns
Figures 4 and 10
SP3481/SP3485 RECEIVER
DC Characteristics
Differential Input Threshold
-0.2
+0.2
Volts
-7V
V
CM
+12V
Input Hysteresis
20
mV
V
CM
= 0V
Output Voltage High
V
CC
-0.4
Volts
V
ID
= +200mV, -1.5mA
Output Voltage Low
0.4
Volts
V
ID
= -200mV, 2.5mA
Three-State (High Impedance)
Output Current
+1
A
0V
V
O
V
CC
; RE = V
CC
Input Resistance
12
15
k
-7V
V
CM
+12V
Input Current (A, B); V
IN
= 12V
1.0
mA
DE = 0V, V
CC
= 0V or 3.6V, V
IN
= 12V
Input Current (A, B); V
IN
= -7V
-0.8
mA
DE = 0V, V
CC
= 0V or 3.6V, V
IN
= -7V
Short-Circuit Current
7
60
mA
0V
V
CM
V
CC
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
............................................................................................. +6.0V
Input Voltages
Logic ..................................................... -0.3V to +6.0V
Drivers ................................................... -0.3V to +6.0V
Receivers ............................................................
15V
Output Voltages
Drivers ..................................................................
15V
Receivers .............................................. -0.3V to +6.0V
Storage Temperature ................................................ .-65C to +150C
Power Dissipation per Package
8-pin NSOIC (derate 6.90mW/
o
C above +70
o
C) ..................... 600mW
8-pin PDIP (derate 11.8mW/
o
C above +70
o
C) ...................... 1000mW
3
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2002 Sipex Corporation
SPECIFICATIONS (continued)
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V
5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
SP3481/SP3485 RECEIVER
AC Characteristics
Maximum Data Rate
10
Mbps
RE = 0V, DE = 0V
Receiver Input to Output, t
PLH
40
70
100
ns
Figures 6 and 11
70
ns
T
AMB
= +25
o
C, V
CC
= +3.3V,
Figures 6 and 11
Receiver Input to Output, t
PHL
40
70
100
ns
Figures 6 and 11
70
ns
T
AMB
= +25
o
C, V
CC
= +3.3V,
Figures 6 and 11
Differential Receiver Skew
4
ns
t
RSKEW
=
t
RPHL
-
t
RPLH
,
Figures 6 and 11
Receiver Enable to
Output Low
35
60
ns
Figures 7 and 12; S
1
closed, S
2
open
Receiver Enable to
Output High
35
60
ns
Figures 7 and 12; S
2
closed, S
1
open
Receiver Disable from Low
35
60
ns
Figures 7 and 12; S
1
closed, S
2
open
Receiver Disable from High
35
60
ns
Figures 7 and 12; S
2
closed, S
1
open
SP3481 Shutdown Timing
Time to Shutdown
50
75
200
ns
RE = 3.3V, DE = 0V
Driver Enable from Shutdown
to Output High
65
150
ns
Figures 4 and 10
Driver Enable from Shutdown
to Output Low
65
150
ns
Figures 5 and 10
Receiver Enable from
Shutdown to Output High
50
200
ns
Figures 7 and 12; S
2
closed, S
1
open
Receiver Enable from
Shutdown to Output Low
50
200
ns
Figures 7 and 12; S
1
closed, S
2
open
POWER REQUIREMENTS
Supply Current
SP3481/3485
No Load
1000
2000
A
RE, DI = 0V or V
CC
; DE = V
CC
800
1500
A
RE = 0V, DI = 0V or V
CC
; DE = 0V
SP3481
Shutdown Mode
10
A
DE = 0V, RE=V
CC
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2000 Sipex Corporation
4
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 V
CC
DESCRIPTION
The SP3481 and the SP3485 are 2 members
in the family of +3.3V low power half-duplex
transceivers that meet the specifications of the
RS-485 and RS-422 serial protocols. These
devices are pin-to-pin compatible with the Sipex
SP481, SP483, and SP485 devices as well as
popular industry standards. The SP3481 and
the SP3485 feature Sipex's BiCMOS process
allowing low power operation without sacrificing
performance.
Drivers
The driver outputs of the SP3481 and SP3485
are differential outputs meeting the RS-485 and
RS-422 standards. The typical voltage output
swing with no load will be 0 Volts to +3.3 Volts.
With a load of 54
across the differential
outputs, the drivers maintain greater than
1.5V voltage levels. The drivers of the SP3481
and SP3485 have an enable control line which
is active HIGH. A logic HIGH on DE (pin 3)
will enable the differential driver outputs.
A logic LOW on DE (pin 3) will tri-state the
driver outputs.
The tranceivers in the SP3481 and SP3485
operate up to 10Mbps. The 250mA I
SC
maximum limit on the driver output allows
the SP3481 and the SP3485 to withstand an
infinite short circuit over the -7.0V to +12.0V
common mode range without catastrophic
damage to the IC.
SP3481/SP3485
Pinout (Top View)
RO 1
RE 2
DE 3
DI 4
8 V
CC
7 B
6 A
5 GND
D
R
SP485
Top View
Receivers
The SP3481 and SP3485 receivers have
differential inputs with an input sensitivity as
low as
200mV. Input impedance of the
receivers is typically 15k
(12k minimum).
A wide common mode range of -7V to +12V
allows for large ground potential differences
between systems. The receivers of the SP3481
and SP3485 have a tri-state enable control pin.
A logic LOW on RE (pin 2) will enable the
receiver, a logic HIGH on RE (pin 2) will disable
the receiver.
The receivers of the SP3481 and SP3485 operate
up to 10Mbps. The receiver for each of the three
devices is equipped with fail-safe. Fail-safe
guarantees that the receiver output will be in a
HIGH state when the input is left unconnected.
Shutdown Mode for the SP3481
The SP3481 is equipped with a Shutdown mode.
To enable the Shutdown state, both the driver
and receiver must be disabled simultaneously.
A logic LOW on DE (pin 3) and a logic HIGH on
RE (pin 2) will put the SP3481 into Shutdown
mode. In Shutdown, supply current will drop to
typical 1
A, 10A maximum.
5
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2002 Sipex Corporation
INPUTS
OUTPUTS
LINE
RE
DE
DI CONDITION
B
A
X
1
1
No Fault
0
1
X
1
0
No Fault
1
0
X
0
X
X
Z
Z
INPUTS
OUTPUTS
RE
DE
A - B
R
0
0
+0.2V
1
0
0
-0.2V
0
0
0
Inputs Open
1
1
0
X
Z
Table 1. Transmit Function Truth Table
Table 2. Receive Function Truth Table
Figure 2. Driver Propagation Delay Test Circuit
Figure 4. Driver Enable and Disable Timing Circuit,
Output HIGH
Figure 1. Driver DC Test Load Circuit
Figure 6. Receiver Propagation Delay Test Circuit
Figure 7. Receiver Enable and Disable Timing Circuit
R
R
V
OC
D
V
CC
V
OD
GENERATOR
(NOTE 1)
50
V
CC
S1
V
DM
R
L
= 27
OUT
C
L
= 15pF
(NOTE 2)
V
OM
= 1.5V
V
OH
+ V
OL
2
D
GENERATOR
(NOTE 1)
50
S1
R
L
= 110
OUT
C
L
= 50pF
(NOTE 2)
V
OM
= 1.5V
V
OH
+ V
OL
2
D
GENERATOR
(NOTE 1)
50
S1
R
L
= 110
OUT
C
L
= 50pF
(NOTE 2)
D
0V OR 3V
V
CC
GENERATOR
(NOTE 1)
50
1.5V
0V
V
ID
R
OUT
C
L
= 15pF
(NOTE 2)
V
OM
= V
CC
2
1.5V
-1.5V
S3
V
ID
GENERATOR
(NOTE 1)
50
C
L
= 15pF
(NOTE 2)
R
1k
S1
S2
V
CC
Figure 5. Driver Enable and Disable Timing Circuit,
Output LOW
GENERATOR
(NOTE 1)
50
C
L
OUT
D
V
CC
R
L
=
60
C
L
= 15pF (NOTE 2)
Figure 3. Driver Differential Output Delay and Transition
Time Circuit
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2000 Sipex Corporation
6
Figure 8. Driver Propagation Delay Waveforms
Figure 12. Receiver Enable and Disable Waveforms
Figure 11. Receiver Propagation Delay Waveforms
Figure 10. Driver Enable and Disable Timing Waveforms
0V
V
OH
t
PLH
t
PHL
V
OM
t
PHL
t
PLH
3V
V
OL
V
OH
1.5V
1.5V
INPUT
Y OUTPUT
V
OM
Z OUTPUT
V
OL
V
OM
V
OM
V
OM
= V
OH
+ V
OL
2
1.5V
0V
V
OH
t
PZH
0.25V
t
PHZ
V
OM
t
PZL
t
PLZ
3V
V
OL
V
CC
1.5V
1.5V
DE
OUTPUT
HIGH
V
OM
0.25V
0V
OUTPUT
LOW
V
OM
= V
OH
+ V
OL
2
1.5V
3V
0V
V
CC
t
RPLH
1.5V
t
RPHL
V
OM
V
OM
0V
1.5V
INPUT
OUTPUT
V
OM
= V
CC
2
NOTE 1: The input pulse is supplied by a generator with the following characteristics:
PRR=250KHz, 50% duty cycle, t
r
< 6.0ns, Z
0
=50
.
NOTE 2: C
L
includes probe and stray capacitance.
IN
1.5V
t
DO1
1.5V
t
DO2
3V
0V
OUT
50%
50%
10%
10%
90%
90%
t
TD
t
TD
2.0V
-2.0V
Figure 9. Driver Differential Output Delay and Transition
Time Waveforms
3V
0V
t
PRHZ
1.5V
t
PRZH
t
PRSH
1.5V
1.5V
10%
0V
V
OH
RE
OUTPUT
S1 is open
S2 is closed
S3 = 1.5V
3V
0V
t
PRLZ
1.5V
t
PRZL
t
PRSL
1.5V
1.5V
10%
V
CC
RE
OUTPUT
S1 is closed
S2 is open
S3 = -1.5V
V
OL
7
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2002 Sipex Corporation
D
ALTERNATE
END PINS
(BOTH ENDS)
D1 = 0.005" min.
(0.127 min.)
E
PACKAGE: PLASTIC
DUALINLINE
(NARROW)
DIMENSIONS (Inches)
Minimum/Maximum
(mm)
A = 0.210" max.
(5.334 max).
E1
C
L
A2
A1 = 0.015" min.
(0.381min.)
B
B1
e = 0.100 BSC
(2.540 BSC)
e
A
= 0.300 BSC
(7.620 BSC)
A2
B
B1
C
D
E
E1
L
0.115/0.195
(2.921/4.953)
0.014/0.022
(0.356/0.559)
0.045/0.070
(1.143/1.778)
0.008/0.014
(0.203/0.356)
0.355/0.400
(9.017/10.160)
0.300/0.325
(7.620/8.255)
0.240/0.280
(6.096/7.112)
0.115/0.150
(2.921/3.810)
0/ 15
(0/15)
8PIN
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2000 Sipex Corporation
8
D
E
H
PACKAGE: PLASTIC
SMALL OUTLINE (SOIC)
(NARROW)
DIMENSIONS (Inches)
Minimum/Maximum
(mm)
8PIN
A
A1
L
B
e
h x 45
A
A1
B
D
E
e
H
h
L
0.053/0.069
(1.346/1.748)
0.004/0.010
(0.102/0.249
0.014/0.019
(0.35/0.49)
0.189/0.197
(4.80/5.00)
0.150/0.157
(3.802/3.988)
0.050 BSC
(1.270 BSC)
0.228/0.244
(5.801/6.198)
0.010/0.020
(0.254/0.498)
0.016/0.050
(0.406/1.270)
0/8
(0/8)
9
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
Copyright 2002 Sipex Corporation
ORDERING INFORMATION
Model
Temperature Range
Package
SP3481CN .................................................................................... 0C to +70C ............................................................................ 8-pin Narrow SOIC
SP3481CP .................................................................................... 0C to +70C ................................................................................ 8-pin Plastic DIP
SP3481EN .................................................................................. .-40C to +85C .......................................................................... 8-pin Narrow SOIC
SP3481EP ................................................................................... -40C to +85C .............................................................................. 8-pin Plastic DIP
SP3485CN .................................................................................... 0C to +70C ............................................................................ 8-pin Narrow SOIC
SP3485CP .................................................................................... 0C to +70C ................................................................................ 8-pin Plastic DIP
SP3485EN ................................................................................... -40C to +85C .......................................................................... 8-pin Narrow SOIC
SP3485EP ................................................................................... -40C to +85C .............................................................................. 8-pin Plastic DIP
Please consult the factory for pricing and availability on a Tape-On-Reel option.
Corporation
SIGNAL PROCESSING EXCELLENCE
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Sales Office
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
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