®
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
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 1
RE 2
DE 3
DI 4
R
8 Vcc
7 B
6 A
D
SP3481 and SP3485
5 GND
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.
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 ................................................ .-65˚C to +150˚C
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
SPECIFICATIONS
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V
±
5% unless otherwise noted.
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
V
OUT
= HIGH
V
OUT
= LOW
SP3481/SP3485 DRIVER
AC Characteristics
Maximum Data Rate
Driver Input to Output, t
PLH
Driver Input to Output, t
PHL
MIN.
TYP.
MAX.
UNITS
CONDITIONS
GND
2
1.5
V
CC
V
CC
V
CC
0.2
3
Volts
Volts
Volts
Volts
Volts
Volts
Volts
µA
mA
mA
Unloaded; R =
∞;
Figure 1
with load; R = 50Ω; (RS-422);
Figure 1
with load; R = 27Ω; (RS-485);
Figure 1
R = 27Ω or R = 50Ω;
Figure 1
R = 27Ω or R = 50Ω;
Figure 1
Applies to DE, DI, RE
Applies to DE, DI, RE
Applies to DE, DI, RE
-7V
≤
V
O
≤
+12V
-7V
≤
V
O
≤
+12V
2.0
0.8
±10
±250
±250
10
20
20
40
40
2
5
52
60
40
60
60
60
10
20
120
120
120
120
Mbps
ns
ns
ns
ns
ns
ns
ns
ns
RE = V
CC
, DE = V
CC
Figures 2 and 8
Figures 2 and 8
t
DO1
- t
DO2
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
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
-0.2
Input Hysteresis
Output Voltage High
V
CC
-0.4
Output Voltage Low
Three-State (High Impedance)
Output Current
Input Resistance
12
Input Current (A, B); V
IN
= 12V
Input Current (A, B); V
IN
= -7V
Short-Circuit Current
7
10/15/02
+0.2
20
0.4
+1
15
1.0
-0.8
60
Volts
mV
Volts
Volts
µA
kΩ
mA
mA
mA
-7V
≤
V
CM
≤
+12V
V
CM
= 0V
V
ID
= +200mV, -1.5mA
V
ID
= -200mV, 2.5mA
0V
≤
V
O
≤
V
CC
; RE = V
CC
-7V
≤
V
CM
≤
+12V
DE = 0V, V
CC
= 0V or 3.6V, V
IN
= 12V
DE = 0V, V
CC
= 0V or 3.6V, V
IN
= -7V
0V
≤
V
CM
≤
V
CC
© Copyright 2000 Sipex Corporation
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
2
SPECIFICATIONS
(continued)
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V
±
5% unless otherwise noted.
PARAMETERS
SP3481/SP3485 RECEIVER
AC Characteristics
Maximum Data Rate
Receiver Input to Output, t
PLH
MIN.
TYP.
MAX.
UNITS
CONDITIONS
10
40
70
100
70
100
70
Mbps
ns
ns
ns
ns
ns
RE = 0V, DE = 0V
Figures 6 and 11
T
AMB
= +25
o
C, V
CC
= +3.3V,
Figures 6 and 11
Receiver Input to Output, t
PHL
40
70
Figures 6 and 11
T
AMB
= +25
o
C, V
CC
= +3.3V,
Figures 6 and 11
t
RSKEW
= t
RPHL
- t
RPLH
,
Figures 6 and 11
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
4
35
35
35
35
60
60
60
60
ns
ns
ns
ns
Figures 7 and 12;
S
1
closed, S
2
open
Figures 7 and 12;
S
2
closed, S
1
open
Figures 7 and 12;
S
1
closed, S
2
open
Figures 7 and 12;
S
2
closed, S
1
open
RE = 3.3V, DE = 0V
50
75
65
65
50
50
200
150
150
200
200
ns
ns
ns
ns
ns
Figures 4 and 10
Figures 5 and 10
Figures 7 and 12;
S
2
closed, S
1
open
Figures 7 and 12;
S
1
closed, S
2
open
1000
800
2000
1500
10
µA
µA
µA
RE, DI = 0V or V
CC
; DE = V
CC
RE = 0V, DI = 0V or V
CC
; DE = 0V
DE = 0V, RE=V
CC
10/15/02
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
© Copyright 2002 Sipex Corporation
3
PIN FUNCTION
RO 1
R
8
V
CC
Pin 1 – RO – Receiver Output.
Pin 2 – RE – Receiver Output Enable Active LOW.
RE 2
7
B
Pin 3 – DE – Driver Output Enable Active HIGH.
Pin 4 – DI – Driver Input.
Pin 5 – GND – Ground Connection.
DE 3
6
A
D
DI 4
SP485
Top View
5
GND
Pin 6 – A – Driver Output/Receiver Input
Non-inverting.
Pin 7 – B – Driver Output/Receiver Input Inverting.
Pin 8 – V
CC
SP3481/SP3485
Pinout (Top View)
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 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 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.
Receivers
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
V
DM
R
S1
R
L
= 27Ω
D
V
CC
V
OD
R
GENERATOR
(NOTE 1)
50Ω
D
OUT
C
L
= 15pF
(NOTE 2)
V
OC
V
CC
V
OM
= V
OH
+ V
OL
2
1.5V
Figure 1. Driver DC Test Load Circuit
Figure 2. Driver Propagation Delay Test Circuit
S1
D
OUT
C
L
= 50pF
(NOTE 2)
GENERATOR
(NOTE 1)
50Ω
R
L
= 110Ω
C
L
D
GENERATOR
(NOTE 1)
50Ω
V
CC
R
L
=
60Ω
OUT
C
L
= 15pF (NOTE 2)
V
OM
= V
OH
+ V
OL
2
1.5V
Figure 3. Driver Differential Output Delay and Transition
Time Circuit
V
CC
R
L
= 110Ω
S1
0V OR 3V
D
C
L
= 50pF
(NOTE 2)
GENERATOR
(NOTE 1)
50Ω
OUT
Figure 4. Driver Enable and Disable Timing Circuit,
Output HIGH
V
ID
GENERATOR
(NOTE 1)
R
OUT
C
L
= 15pF
(NOTE 2)
50Ω
1.5V
0V
V
OM
= V
CC
2
Figure 5. Driver Enable and Disable Timing Circuit,
Output LOW
Figure 6. Receiver Propagation Delay Test Circuit
1.5V
-1.5V
S3
1k
V
ID
R
S1
V
CC
S2
C
L
= 15pF
(NOTE 2)
GENERATOR
(NOTE 1)
50Ω
Figure 7. Receiver Enable and Disable Timing Circuit
INPUTS
RE
X
X
X
DE
1
1
0
DI
1
0
X
LINE
CONDITION
No Fault
No Fault
X
OUTPUTS
B
0
1
Z
A
1
0
Z
INPUTS
RE
DE
0
0
0
0
0
0
1
0
OUTPUTS
A-B
R
+0.2V
1
-0.2V
0
Inputs Open
1
X
Z
© Copyright 2002 Sipex Corporation
Table 1. Transmit Function Truth Table
10/15/02
Table 2. Receive Function Truth Table
SP3481/3485 Low Power Half-Duplex RS485 Transceivers
5
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