1
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
OA1 OB1 OA2 OB2 V
DESCRIPTION...
The SP495 is a quad differential line driver/receiver meeting both RS-485 and RS-422
standards at data rates beyond 10Mbps. The SP495 features three half-duplex transceivers
suitable for data bus connections and a fourth full-duplex transceiver with independent driver,
receiver enables. Ideal for use as a control bus transceiver. A complete SCSI initiator or target
interface can be implemented using five SP495s. Propagation Delay Skew is tightly specified
to aid in parallel interface designs. The SP495 is available in a 20-pin plastic SOIC package
for operation over the commercial and industrial temperature ranges. For PLCC availability,
please consult factory.
s
Pinout for SCSI Interface
s
Meets EIA-485 Standard for Multipoint
Bus Transmission
s
+5V-Only Power Supply Required
s
Receiver Fail-Safe Mode
s
Low Power BiCMOS Technology
s
Glitch-Free Power-Up/Down
s
Available in 20-Pin Plastic SOIC
s
Pin Compatible with DS36954
SP495
R
4
D
4
R
3
D
3
R
2
D
2
R
1
D
1
20
19 18 17 16
2 1 3 4 11
15 14 13 12
6 5 8 9 7 10
DR1 DE1/RE1 DR2 DE2/ RE2
GND DR3 DE3/ RE3 DI4 DE4 RO4 RE4
cc OA3 OB3 OA4 OB4
SP495
Quad Differential RS-485 Transceiver
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
2
SPECIFICATIONS
T
MIN
to T
MAX
and V
CC
= 5V
5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
DRIVER
DC Characteristics
Differential Output Voltage
GND
V
CC
Volts
Unloaded; R =
;
see Figure 1
Differential Output Voltage
2
V
CC
Volts
With Load; R = 50
; (RS-422);
see Figure 1
Differential Output Voltage
1.5
V
CC
Volts
With Load; R = 27
; (RS-485);
see Figure 1
Change in Magnitude of Driver
Differential Output Voltage for
Complimentary States
0.2
Volts
R = 27
or R = 50
;
see Figure 1
Driver Common-Mode
Output Voltage
3
Volts
R = 27
or R = 50
;
see Figure 1
Input High Voltage
2.0
Volts
Applies to DRx, DEx/ REx
Input Low Voltage
0.8
Volts
Applies to DRx, DEx/ REx
Input Current
10
A
Applies to DRx, DEx/ REx
Driver Short-Circuit Current
V
OUT
= HIGH
250
mA
-7V
V
O
10V
V
OUT
= LOW
250
mA
-7V
V
O
10V
DRIVER
AC Characteristics
Maximum Driver Data Rate
10
Mbps
R
DIFF
= 54
, C
L1
= C
L2
= 100pF
Driver Input to Output
20
30
60
ns
t
PLH
; R
DIFF
= 54
, C
L1
= C
L2
= 100pF;
see Figures 3 and 6
Driver Input to Output
20
30
60
ns
t
PHL
; R
DIFF
= 54
, C
L1
= C
L2
= 100pF;
see Figures 3 and 6
Driver Skew
10
ns
see Figures 3 and 6
Driver Rise or Fall Time
3
15
40
ns
From 10% to 90%; R
DIFF
= 54
,
C
L1
= C
L2
= 100pF;
see Figures 3 and 6
Driver Enable to Output HIGH
40
70
ns
C
L1
= C
L2
= 100pF;
see Figures
4 and 7; S
2
closed
Driver Enable to Output LOW
40
70
ns
C
L1
= C
L2
= 100pF;
see Figures
4 and 7; S
1
closed
Driver Disable Time from LOW
40
70
ns
C
L1
= C
L2
= 15pF;
see Figures
4 and 7; S
1
closed
Driver Disable Time from HIGH
40
70
ns
C
L1
= C
L2
= 15pF;
see Figures
4 and 7; S
2
closed
RECEIVER
DC Characteristics
Differential Input Threshold
-0.2
+0.2
Volts
-7V
V
CM
12V
Input Hysteresis
70
mV
V
CM
= 0V
Output Voltage HIGH
3.5
Volts
I
O
= -4mA, V
ID
= +200mV
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
............................................................................................................................+7V
Input Voltages
Logic...................................................-0.5V to (V
CC
+0.5V)
Drivers................................................-0.5V to (V
CC
+0.5V)
Receivers....................................................................15V
Output Voltages
Logic...................................................-0.5V to (V
CC
+0.5V)
Drivers...........................................................-8V to 12.5V
Receivers...........................................-0.5V to (V
CC
+0.5V)
Storage Temperature....................................................-65C to +150C
Power Dissipation.....................................................................1000mW
3
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
A
B
R
R
V
OD
V
OC
1k
1k
C
RL
Receiver
Output
S
1
S
2
Test Point
V
CC
Figure 1. Driver DC Test Load Circuit
Figure 2. Receiver Timing Test Load Circuit
Operating Temperature
Commercial (_C_)
0
+70
C
Industrial (_E_)
-40
+85
C
Storage Temperature
-65
+150
C
Package
Plastic LCC (_L)
SPECIFICATIONS (continued)
T
MIN
to T
MAX
and V
CC
= 5V
5% unless otherwise noted.
PARAMETERS
MIN.
TYP.
MAX.
UNITS
CONDITIONS
RECEIVER
DC Characteristics
Output Voltage LOW
0.4
Volts
I
O
= +4mA, V
ID
= -200mV
Three State (high impedance)
Output Current
0.5
10
A
0.4V
V
O
2.4V; DEx/ REx = 5V
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 5.25V, V
IN
= 12V
Input Current (A, B); V
IN
= -7V
-0.8
mA
DE = 0V, V
CC
= 0V or 5.25V, V
IN
= -7V
Short-Circuit Current
85
mA
0V
V
O
V
CC
RECEIVER
AC Characteristics
Maximum Data Rate
10
Mbps
DEx/ REx = 0V
Receiver Input to Output
60
200
ns
t
PLH
; R
DIFF
= 54
,
C
L1
= C
L2
=
100pF;
Figures 3 & 8
Receiver Input to Output
60
200
ns
t
PHL
; R
DIFF
= 54
,
C
L1
= C
L2
=
100pF;
Figures 3 & 8
Diff. Receiver Skew It
PLH
-t
PHL
I
13
ns
R
DIFF
= 54
; C
L1
= C
L2
= 100pF;
Figures 3 & 8
Receiver Enable to Output LOW
45
70
ns
C
RL
= 15pF;
Figures 2 and 9; S
1
closed
Receiver Enable to Output HIGH
45
70
ns
C
RL
= 15pF;
Figures 2 and 9; S
2
closed
Receiver Disable from LOW
45
70
ns
C
RL
= 15pF;
Figures 2 and 9; S
1
closed
Receiver Disable from HIGH
45
70
ns
C
RL
= 15pF;
Figures 2 and 9; S
2
closed
POWER REQUIREMENTS
Supply Voltage
+4.75
+5.25
Volts
Supply Current
2
5
mA
DEx/ REx, DRx = 0V or V
CC
ENVIRONMENTAL AND
MECHANICAL
C
L1
15pF
RO
A
B
A
B
DI
DE
3V
C
L2
R
DIFF
500
C
L
Output
Under
Test
S
1
S
2
V
CC
Figure 3. Driver/Receiver Timing Test Circuit
Figure 4. Driver Timing Test Load #2 Circuit
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
4
+3V
0V
DE
5V
V
OL
A, B
0V
1.5V
1.5V
t
ZL
t
ZH
f = 1MHz; t
R
< 10ns; t
F
< 10ns
V
OH
A, B
2.3V
2.3V
t
LZ
t
HZ
0.5V
0.5V
Output normally LOW
Output normally HIGH
Figure 7. Driver Enable and Disable Times
+3V
0V
DI
B
A
DRIVER
OUTPUT
V
O
+
DIFFERENTIAL
OUTPUT
V
A
V
B
0V
V
O
t
SKEW
t
SKEW
1.5V
1.5V
t
PLH
t
PLH
t
R
t
F
f = 1MHz; t
R
< 10ns; t
F
< 10ns
V
O
1/2V
O
1/2V
O
t
PHL
Figure 6. Driver Propagation Delays
V
OH
V
OL
R
1.5V
1.5V
t
PHL
f = 1MHz; t
R
10ns; t
F
10ns
OUTPUT
V
0D2
+
V
0D2
A B
0V
0V
t
PHL
INPUT
Figure 8. Receiver Propagation Delays
5
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
+3V
0V
RE
5V
R
0V
1.5V
1.5V
t
ZL
t
ZH
f = 1MHz; t
R
< 10ns; t
F
< 10ns
R
1.5V
1.5V
t
LZ
t
HZ
0.5V
0.5V
Output normally LOW
Output normally HIGH
V
IL
V
IH
Figure 9. Receiver Enable and Disable Times
DESCRIPTION
General Description...
The SP495 is a quad differential transceiver that
meets the requirements of RS-485, RS-422, and
differential SCSI at data rates to beyond 10Mbps.
Fabricated with a proprietary Sipex BiCMOS
process, the SP495 requires only a fraction of the
power of older bipolar designs.
The SP495 features three half-duplex transceivers
suitable for data bus connections and a fourth
full-duplex transceiver with independent enables
ideal for use as a control bus transceiver. A
complete SCSI initiator or target interface can be
implemented using five SP495s.
The RS-485 standard is ideal for multi-drop
applications and for long-distance interfaces.
RS-485 allows up to 32 drivers and 32 receivers
to be connected to a single data bus, making it an
ideal choice for multi-drop applications. Since
the cabling can be as long as 4,000 feet, RS-485
transceivers are specified for operation with a
wide (-7V to +12V) common mode range to
accommodate ground potential differences.
Because RS-485 is a low impedance differential
interface, data is virtually immune to noise in the
transmission line.
Drivers...
The differential drivers for the SP495 have typical
output voltage swings (no load) of 0 to +5Volts.
With loading to the RS-485 specification (54
),
drivers must maintain outputs greater than 1.5V.
The three half-duplex drivers of the SP495 have
independent Driver Enable control lines which
are active HIGH. A logic HIGH on DEx (pins 1,
4, or 5 of the SP495) will enable the addressed
differential driver output. A logic LOW on DEx
will tri-state the driver output and enable the
receiver. The fourth driver is controlled by its
own DE4 Enable line and can be used in half -
duplex or full-duplex modes.
Receivers...
The differential receivers for the SP495 have an
input sensitivity of
200mV. Input impedance is
typically 15k
(12k
minimum). A wide
common mode range of -7V to +12V allows for
large ground potential differences between widely
separated systems. These receivers are equipped
with a fail-safe feature which guarantees that the
receiver output will be in a HIGH state when the
input is left unconnected (note: this feature
operates with floating inputs, not terminated
inputs).
Like the half-duplex drivers, the three half-duplex
receivers of the SP495 have independent Re-
ceiver Enable control lines which are active
LOW. A logic LOW on REx (pins 1, 4, or 5 of
the SP495) enables the differential receivers. A
logic HIGH on REx tri-states the receivers. The
fourth receiver is controlled by its own RE4
Enable line and can be used in half-duplex or
full-duplex modes.
SP495
Quad Differential RS-485 Transceiver
Copyright 2000 Sipex Corporation
6
ORDERING INFORMATION
Model
Temperature Range
Package
SP495CT. ......................................................... 0C to +70C ...................................................... 20-Pin SOIC
SP495ET ........................................................ -40C to +85C .................................................... 20-Pin SOIC
For PLCC availability, please consult factory.
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
22 Linnell Circle
Billerica, MA 01821
TEL: (978) 667-8700
FAX: (978) 670-9001
e-mail: sales@sipex.com
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
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