SP3485
+3.3V Low Power Half-Duplex RS-485
Transceiver with 10Mbps Data Rate
• RS-485 and RS-422 Transceiver
• Operates from a single +3.3V Supply
• Interoperable with +5.0V logic
• Driver/Receiver Enable
• -7V to +2V Common-Mode Input Voltage Range
• Allows up to 32 transceivers on the serial bus
• Compatibility with industry standard 7576 pinout
• Driver Output Short-Circuit Protection
DESCRIPTION
The
SP3485
device is a +3.3V low power half-duplex transceiver that meets the specifica-
tions of the RS-485 and RS-422 serial protocols. This device is pin-to-pin compatible with
the
Exar
SP48, SP483 and SP485 devices as well as popular industry standards. The
SP3485
features the
Exar
BiCMOS process, allowing low power operation without sacrificing
performance. The
SP3485
can meet the electrical specifications of the RS-485 and RS-422
serial protocols up to 0Mbps under load.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com
SP3485_00_0692
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.........................................+/-5V
Output Voltages
Drivers.............................................+/-5V
Receivers............................-0.3V to +6.0V
Storage Temperature.......................-65˚C to +150˚C
Power Dissipation
8-pin NSOIC...................................................600mW
(derate 6.90mW/ºC above +70ºC)
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V +/-5% unless otherwise noted.
ELECTRICAL CHARACTERISTICS
MAX.
UNITS
CONDITIONS
PARAMETERS
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
Driver Short Circuit Current
V
OUT
= LOW
SP3485 DRIVER
AC Characteristics
Maximum Data Rate
Driver Input to Output, t
PLH
Driver Input to Output, t
PHL
Differential Driver Skew
Driver Rise or Fall Time
MIN.
TYP.
GND
2
.5
Vcc
Vcc
Vcc
0.2
Volts
Volts
Volts
Volts
Unloaded; R = ∞Ω ; Figure 1
With Load; R = 50Ω (RS-422);
Figure
With Load; R = 27Ω (RS-485);
Figure
R = 27Ω or R = 50Ω; Figure 1
3
2.0
0.8
+/-0
+/-250
+/-250
Volts
Volts
Volts
µA
mA
mA
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; Figure 8
-7V ≤ V
O
≤ +12V; Figure 8
0
20
20
40
40
2
5
60
60
0
20
Mbps
ns
ns
ns
ns
RE = V
CC
, DE = V
CC
Figures 2 & 9
Figures 2 & 9
|t
DO
- t
DO2
|, Figures 2 and 0
From 0%-90%; Figures 3 and 0
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com
SP3485_00_0692
2
T
AMB
= T
MIN
to T
MAX
and V
CC
= +3.3V +/-5% unless otherwise noted.
ELECTRICAL CHARACTERISTICS
MAX.
20
20
20
20
UNITS
ns
ns
ns
ns
CONDITIONS
Figures 4 and
Figures 5 and
Figures 5 and
Figures 4 and
PARAMETERS
Driver Enable to Output High
Driver Enable to Output Low
Driver Disable Time from Low
Driver Disable Time from High
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); V
IN
= 2V
Input Current (A, B); V
IN
= -7V
Short Circuit Current
SP3485 RECEIVER
AC Characteristics
Maximum Data Rate
Receiver Input to Output, t
PLH
Receiver Input to Output, t
PLH
Receiver Input to Output, t
PHL
Receiver Input to Output, t
PHL
Differential Receiver Skew
Receiver Enable to Output Low
Receiver Enable to Output High
Receiver Disable from Low
Receiver Disable from High
POWER REQUIREMENTS
Supply Current , No Load
Supply Current , No Load
MIN.
TYP.
52
60
40
60
SP3485 DRIVER AC Characteristics continued
-0.2
20
Vcc-0.4
+0.2
Volts
mV
Volts
-7V ≤ V
CM
≤ +12V
V
CM
= 0V
V
ID
= +200mV, -.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
= 2V
DE = 0V, V
CC
= 0V or 3.6V,
V
IN
= -7V
0V ≤ V
CM
≤ V
CC
0.4
+/-
2
5
+.0
-0.8
7
60
Volts
µA
kΩ
mA
mA
mA
0
40
70
00
70
40
70
00
70
4
35
35
35
35
60
60
60
60
Mbps
ns
ns
ns
ns
ns
ns
ns
ns
ns
RE = 0V, DE = 0V
Figures 6 and 2
T
AMB
= +25°C, Vcc = 3.3V,
Figures 6 and 2
Figures 6 and 2
T
AMB
= +25°C, Vcc = 3.3V,
Figures 6 and 2
t
RSKEW
= |t
RPHL
- t
RPLH
|,
Figures 6 and 2
Figures 7 and 3,
S
closed, S
2
open
Figures 7 and 3,
S
2
closed, S
open
Figures 7 and 3,
S
closed, S
2
open
Figures 7 and 3,
S
2
closed, S
open
RE, DI = 0V or V
CC
; DE = V
CC
RE = 0V, DI = 0V or V
CC
, DE = 0V
000
800
2000
500
µA
µA
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com
SP3485_00_0692
3
Pin Function SP3485
Pin - RO - Receiver output
PIN FUNCTION
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 - Non-Inverting Driver Output/Receiver Input
Pin 7 - B - Inverting Driver Output/Receiver Input
Pin 8 - Vcc - Positive Supply
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com
SP3485_00_0692
4
TEST CIRCUITS
V
DM
R
L
= 27Ω
S1
D
OUT
C
L
= 15pF
(NOTE 2)
R
D
Vcc
V
OD
R
V
OC
GENERATOR
(NOTE 1)
50Ω
V
CC
V
OM
= V
OH
+ V
OL
≈ 1.5V
2
Figure . Driver DC Test Load Circuit
Figure 2. Driver Propagation Delay Test Circuit
S1
C
L
D
GENERATOR
(NOTE 1)
50Ω
D
OUT
C
L
= 50pF
(NOTE 2)
R
L
= 110Ω
R
L
=
OUT
60Ω
GENERATOR
(NOTE 1)
50Ω
V
CC
C
L
= 15pF (NOTE 2)
V
OM
= V
OH
+ V
OL
≈ 1.5V
2
Figure 3. Driver Differential Output Delay and
Transition Time Circuit.
V
CC
R
L
= 110Ω
OUT
C
L
= 50pF
(NOTE 2)
GENERATOR
(NOTE 1)
50Ω
Figure 4. Driver Enable and Disable Timing Circuit,
Output High
S1
0V OR 3V
D
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
1.5V
-1.5V
S3
1k
V
ID
R
S2
C
L
= 15pF
(NOTE 2)
GENERATOR
(NOTE 1)
Figure 6. Receiver Propagation Delay Test Circuit
S1
V
CC
DE = 0 or Vcc
DI = 0 or Vcc
D
A/Y
I
OSD
100Ω
-7V to +12V V
B/Z
50Ω
Figure 7. Receiver Enable and Disable Timing
Circuit
Figure 8. Driver Short Circuit Current Limit Test
NOTE : The input pulse is supplied by a generator with the following characteristics:
PRR = 250kHz, 50% duty cycle, t
R
< 6.0ns, Z
O
= 50Ω.
NOTE 2: C
L
includes probe and stray capacitance.
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com
SP3485_00_0692
5
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