®
SP3481/SP3485
+3.3V Low Power Half-Duplex RS-485
Transceivers with 10Mbps Data Rate
■ 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
Now Available in Lead Free Packaging
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.
RO
RE
RE
DE
DI
1
2
3
4
R
D
Vcc
8
7
B
6
A
5
GND
SP3481 and SP3485
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2002 Sipex Corporation
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.
VCC ............................................................................................. +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 ................................................ .-65˚C to +150˚C
Power Dissipation per Package
8-pin NSOIC (derate 6.90mW/oC above +70oC) ..................... 600mW
8-pin PDIP (derate 11.8mW/oC above +70oC) ...................... 1000mW
SPECIFICATIONS
TAMB = TMIN to TMAX and VCC = +3.3V ± 5% unless otherwise noted.
TYP.
MIN.
PARAMETERS
SP3481/SP3485 DRIVER
DC Characteristics
Differential Output Voltage
Differential Output Voltage
Differential Output Voltage
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
VOUT = HIGH
VOUT = LOW
SP3481/SP3485 DRIVER
AC Characteristics
Maximum Data Rate
Driver Input to Output, tPLH
Driver Input to Output, tPHL
Differential Driver Skew
Driver Rise or Fall Time
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
SP3481/SP3485 RECEIVER
DC Characteristics
Differential Input Threshold
Input Hysteresis
Output Voltage High
Output Voltage Low
Three-State (High Impedance)
Output Current
Input Resistance
Input Current (A, B); VIN = 12V
Input Current (A, B); VIN = -7V
Short-Circuit Current
GND
2
1.5
2.0
10
20
20
-0.2
12
7
40
40
2
5
52
60
40
60
20
15
VCC-0.4
MAX. UNITS
CONDITIONS
VCC
VCC
VCC
0.2
3
0.8
±10
Volts Unloaded; R = ∞; Figure 1
Volts with load; R = 50Ω; (RS-422); Figure 1
Volts with load; R = 27Ω; (RS-485); Figure 1
Volts R = 27Ω or R = 50Ω; Figure 1
Volts R = 27Ω or R = 50Ω; Figure 1
Volts Applies to DE, DI, RE
Volts Applies to DE, DI, RE
µA
Applies to DE, DI, RE
±250
±250
mA
mA
-7V ≤ VO ≤ +12V
-7V ≤ VO ≤ +12V
Mbps RE = VCC, DE = VCC
60
60
10
20
120
120
120
120
+0.2
0.4
+1
1.0
-0.8
60
ns
ns
ns
ns
ns
ns
ns
ns
Volts
mV
Volts
Volts
µA
kΩ
mA
mA
mA
Figures 2 and 8
Figures 2 and 8
tDO1 - tDO2 Figures 2 and 9
From 10% to 90% ; Figures 3 and 9
Figures 4 and 10
Figures 5 and 10
Figures 5 and 10
Figures 4 and 10
-7V ≤ VCM ≤ +12V
VCM = 0V
VID = +200mV, -1.5mA
VID = -200mV, 2.5mA
0V ≤ VO ≤ VCC; RE = VCC
-7V ≤ VCM ≤ +12V
DE = 0V, VCC = 0V or 3.6V, VIN = 12V
DE = 0V, VCC = 0V or 3.6V, VIN = -7V
0V ≤ VCM ≤ VCC
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2000 Sipex Corporation
2
SPECIFICATIONS (continued)
TAMB = TMIN to TMAX and VCC = +3.3V ± 5% unless otherwise noted.
TYP.
PARAMETERS
SP3481/SP3485 RECEIVER
MIN.
MAX. UNITS
CONDITIONS
AC Characteristics
Maximum Data Rate
Receiver Input to Output, tPLH
10
40
Receiver Input to Output, tPHL
40
50
Differential Receiver Skew
Receiver Enable to
Output Low
Receiver Enable to
Output High
Receiver Disable from Low
Receiver Disable from High
SP3481 Shutdown Timing
Time to Shutdown
Driver Enable from Shutdown
to Output High
Driver Enable from Shutdown
to Output Low
Receiver Enable from
Shutdown to Output High
Receiver Enable from
Shutdown to Output Low
POWER REQUIREMENTS
Supply Current
SP3481/3485
No Load
SP3481
Shutdown Mode
70
70
4
35
35
35
35
75
65
65
50
50
100
70
100
70
60
60
60
60
200
150
150
200
200
1000
800
2000
1500
10
Mbps
ns
ns
RE = 0V, DE = 0V
Figures 6 and 11
TAMB = +25oC, VCC = +3.3V,
Figures 6 and 11
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
ns
µA
µA
µA
Figures 6 and 11
TAMB = +25oC, VCC = +3.3V,
Figures 6 and 11
tRSKEW = tRPHL - tRPLH, Figures 6 and 11
Figures 7 and 12; S1 closed, S2 open
Figures 7 and 12; S2 closed, S1 open
Figures 7 and 12; S1 closed, S2 open
Figures 7 and 12; S2 closed, S1 open
RE = 3.3V, DE = 0V
Figures 4 and 10
Figures 5 and 10
Figures 7 and 12; S2 closed, S1 open
Figures 7 and 12; S1 closed, S2 open
RE, DI = 0V or VCC; DE = VCC
RE = 0V, DI = 0V or VCC; DE = 0V
DE = 0V, RE=VCC
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2002 Sipex Corporation
3
RO 1
RE 2
DE 3
DI 4
R
8 VCC
7 B
6 A
D
SP485
5 GND
Top View
SP3481/SP3485
Pinout (Top View)
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
DESCRIPTION
Receivers
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 54Ω 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 ISC
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.
The SP3481 and SP3485 receivers 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 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 1µA, 10µA maximum.
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2000 Sipex Corporation
4
D
VOD
VCC
R
R
VOC
GENERATOR
(NOTE 1)
50Ω
VDM
RL = 27Ω
OUT
CL = 15pF
(NOTE 2)
S1
D
VCC
VOM = 1.5V
VOH + VOL
2
Figure 1. Driver DC Test Load Circuit
Figure 2. Driver Propagation Delay Test Circuit
CL
RL =
60Ω
OUT
GENERATOR
(NOTE 1)
50Ω
D
VCC
S1
D
CL = 50pF
(NOTE 2)
OUT
RL = 110Ω
GENERATOR
(NOTE 1)
50Ω
CL = 15pF (NOTE 2)
VOM = 1.5V
VOH + VOL
2
Figure 3. Driver Differential Output Delay and Transition
Time Circuit
Figure 4. Driver Enable and Disable Timing Circuit,
Output HIGH
VCC
RL = 110Ω
OUT
S1
CL = 50pF
(NOTE 2)
0V OR 3V
D
GENERATOR
(NOTE 1)
50Ω
GENERATOR
(NOTE 1)
50Ω
1.5V
0V
VID
R
OUT
CL = 15pF
(NOTE 2)
VOM = VCC
2
Figure 5. Driver Enable and Disable Timing Circuit,
Output LOW
Figure 6. Receiver Propagation Delay Test Circuit
S3
1.5V
-1.5V
VID
R
GENERATOR
(NOTE 1)
50Ω
1k
CL = 15pF
(NOTE 2)
S1
S2
VCC
Figure 7. Receiver Enable and Disable Timing Circuit
INPUTS
OUTPUTS
INPUTS
OUTPUTS
LINE
1
1
0
1
0
X
RE DE DI CONDITION B
0
X
1
X
X
Z
No Fault
No Fault
X
Table 1. Transmit Function Truth Table
A
1
0
Z
RE
0
0
0
1
DE
0
0
0
0
A - B
+0.2V
-0.2V
Inputs Open
X
Table 2. Receive Function Truth Table
R
1
0
1
Z
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2002 Sipex Corporation
5
INPUT
Y OUTPUT
Z OUTPUT
3V
0V
VOH
VOL
VOH
VOL
1.5V
tPLH
1.5V
tPHL
VOM
VOM
tPHL
tPLH
VOM
VOM
VOM = VOH + VOL
2
≈ 1.5V
IN
1.5V
1.5V
tDO1
tDO2
90%
90%
OUT
50%
10%
tTD
50%
10%
tTD
3V
0V
2.0V
-2.0V
Figure 8. Driver Propagation Delay Waveforms
Figure 9. Driver Differential Output Delay and Transition
Time Waveforms
DE
OUTPUT
HIGH
OUTPUT
LOW
3V
0V
VOH
0V
VCC
VOL
1.5V
tPZH
1.5V
tPHZ
VOM
0.25V
tPZL
tPLZ
VOM
0.25V
VOM = VOH + VOL
2
≈ 1.5V
INPUT
OUTPUT
3V
0V
VCC
0V
1.5V
tRPLH
1.5V
tRPHL
VOM
VOM
VOM = VCC
2
Figure 10. Driver Enable and Disable Timing Waveforms
Figure 11. Receiver Propagation Delay Waveforms
S1 is open
S2 is closed
S3 = 1.5V
1.5V
tPRHZ
10%
1.5V
tPRZH
tPRSH
S1 is closed
S2 is open
S3 = -1.5V
1.5V
tPRLZ
10%
1.5V
tPRZL
tPRSL
1.5V
3V
0V
VCC
VOL
RE
1.5V
OUTPUT
RE
OUTPUT
3V
0V
VOH
0V
Figure 12. Receiver Enable and Disable Waveforms
NOTE 1: The input pulse is supplied by a generator with the following characteristics:
PRR=250KHz, 50% duty cycle, tr < 6.0ns, Z0=50Ω.
NOTE 2: CL includes probe and stray capacitance.
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2000 Sipex Corporation
6
PACKAGE: PLASTIC
DUAL–IN–LINE
(NARROW)
D1 = 0.005" min.
(0.127 min.)
D
E1
E
A1 = 0.015" min.
(0.381min.)
A = 0.210" max.
(5.334 max).
A2
L
B1
B
e = 0.100 BSC
(2.540 BSC)
ALTERNATE
END PINS
(BOTH ENDS)
C
Ø
eA = 0.300 BSC
(7.620 BSC)
DIMENSIONS (Inches)
Minimum/Maximum
8–PIN
(mm)
A2
B
B1
C
D
E
E1
L
Ø
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°)
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2002 Sipex Corporation
7
PACKAGE: PLASTIC
SMALL OUTLINE (SOIC)
(NARROW)
E H
A
A1
D
e
B
h x 45°
Ø
L
DIMENSIONS (Inches)
Minimum/Maximum
8–PIN
(mm)
A
A1
B
D
E
e
H
h
L
Ø
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°)
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2000 Sipex Corporation
8