Corporation
SP301/302
RS-232/RS-422 Line Drivers/Receivers
SIGNAL PROCESSING EXCELLENCE
s
s
s
s
s
s
RS-232 and RS-422 on One Chip
Multiple Drivers and Receivers
Software-selectable Modes
Loopback for Self-Testing
Short-circuit Protected
24-pin Single-width DIP or SOIC
Package
DESCRIPTION…
The
SP301
and
SP302
are proprietary single-chip devices that contain both RS-232 and RS-422
protocol line drivers and receivers. Their configuration may be changed at any time by logic levels
on two control lines. In any configuration, both the
SP301
and
SP302
fully meet the requirements
of the EIA RS-232D and RS-422 data communication standards. A loopback test mode is
provided.The
SP301
and
SP302
are available in 24-pin single width plastic, and 28-pin SOIC
packages for commercial and industrial temperature range operation.
TOB
1
TOB
2
TOA
1
TOA
2
RIB
1
RIB
2
RIA
1
RIA
2
V
DD
V
CC
V
EE
GND
SELECT
A
B
LOOP–
BACK
SP302
TIB
1
TIB
2
TIA
1
ROB
1
ROB
2
ROA
1
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51
SIGNAL PROCESSING EXCELLENCE
SPECIFICATIONS
(T
MIN
≤
T
A
≤
T
MAX
and nominal supply voltages unless otherwise noted)
PARAMETER
RS-232 DRIVER
TTL Input Level
V
IL
V
IH
High Level Output
Low Level Output
Short Circuit Current
Loopback Output Voltage
Slew rate
Transition Time
Maximum Transmission Rate
RS-232 RECEIVER
Input Voltage Range
Input High Threshold
Input Low Threshold
Input Impedance
TTL Output Level
V
OL
V
OH
Maximum Receiving Rate
RS-422 DRIVER
TTL Input Level
V
IL
V
IH
High Level Output
Low Level Output
Differential Output
MIN.
TYP.
MAX.
UNITS
CONDITIONS
0
2.0
+5.0
-1.5
0.8
-5.0
±30
30
3
V
V
V
V
mA
V
V/µs
µs
kbps
R
L
= 3kΩ, V
IN
= 0.8V
R
L
= 3kΩ, V
IN
= 2.0V
V
OUT
= 0V
R
L
= 3kΩ, V
EE
= -12.0V; Note 1
C
L
= 50pF, R
L
= 3kΩ; T
A
= 25°C
V
OUT
from +3V to -3V or
-3V to +3V
200
-15
+1.75
+0.75
3
2.4
200
+15
+2.5
+1.35
7
0.4
V
V
V
kΩ
V
V
kbps
Note 6
Positive-going
Negative-going
V
SS
≤
V
IN
≤
V
DD
V
CC
= +4.75V, I
OUT
= +1.6mA
V
CC
= +4.75V, I
OUT
= -0.5mA
0
2.0
2.75
±2
0.8
6.0
1.0
±6
±100
±500
400
Short Circuit Current
Output Current
Transition Time
Maximum Transmission Rate 1,000
RS-422 RECEIVER
Common Mode Range
Differential Input
Differential Input Threshold
-0.2
Input Voltage Hysteresis
30
Input Resistance
3
TTL Output Level
V
OL
V
OH
2.4
Maximum Receiving Rate
1,000
Short Circuit Output Current
POWER REQUIREMENTS
V
DD
= +12V,
±10%
V
CC
= +5V;
±10%
V
EE
= -12V,
±10%
ENVIRONMENTAL
Operating Temperature
-CS, –CT
0
-MR
-55
Storage Temperature
-65
V
V
V
V
V
V
mA
µA
ns
kbps
V
V
V
mV
kΩ
V
V
kbps
mA
mA
mA
mA
I
OH
= -20mA
I
OL
= +20mA
R
L
= 100Ω
R
L
=
∞
Note 2
-0.25V
≤
V
O
≤
6V; power off
R
L
= 100Ω, C
L
= 15pF; Note 3
±7
±15
+0.2
Note 4
Note 4 and 6
T
A
= 25°C
V
CM
= 0V; T
A
= 25°C
-7V
≤
V
CM
≤
+7V
V
CC
= +4.75V, I
OUT
= +1.6mA
V
CC
= +4.75V, I
OUT
= -0.5mA
V
OUT
= 0V
Note 5
Note 5
Note 5
0.4
±120
7
5
11
15
7
20
+70
+125
+150
°C
°C
°C
52
Corporation
SIGNAL PROCESSING EXCELLENCE
Notes:
1.
2.
3.
4.
5.
6.
In Loop-back mode
Only one output drive pin per package will be shorted at any time
From 10% to 90% of steady-state
This is an absolute maximum rating; normal operating levels are V < 5V
Outputs unloaded; Inputs tied to GND; T = +25°C; V = 0V; LB=0
Typical SP302 current drains under full load are:
18mA (+12V), 10mA (-12V) and 7mA (+5V) in RS-232 mode only;
5mA (+12V), 7mA (-12V) and 56mA (+5V) in RS-422 mode only;
12mA (+12V), 14mA (-12V) and 31mA (+5V) in RS-232 and RS-422 modes;
RS-232 loads 3kΩ, 2500pF, 20kHz; RS-422 outputs across 100Ω, 500kHz.
In Loopback mode, the external voltage input to the receiver must not exceed
±
10V, otherwise
the loopback test may be adversely affected.
IN
A
IL
TYPICAL PERFORMANCE CURVES
RS-232 Driver
RS-232 Receiver
T
IN
5V
GND
10V
R
IN
5V
GND
–5V
T
OUT
GND
–10V
20kHz
20kHz
R
OUT
5V
GND
RS-422 Driver
RS-422 Receiver
2V
T
IN
GND
T
OUT
5V
GND
–5V
R
IN
2V
GND
–2V
R
OUT
5V
GND
500kHz
500kHz
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53
SIGNAL PROCESSING EXCELLENCE
PIN ASSIGNMENTS
V
DD
(+12V) 1
RIA
2
2
RIA
1
3
TOA
2
4
TOA
1
5
SELECT A 6
SELECT B 7
TOB
1
8
TOB
2
9
RIB
1
10
RIB
2
11
GND 12
24 V
CC
(+5V)
23 N.C.
22 ROA
21 N.C.
20 TIA
19 LB
18 N.C.
17 TIB
16 N.C.
15 ROB
14 N.C.
13 V
EE
(-12V)
V
DD
(+12V) 1
RIA
2
2
RIA
1
3
TOA
2
4
TOA
1
5
SELECT A 6
SELECT B 7
TOB
1
8
TOB
2
9
RIB
1
10
RIB
2
11
GND 12
24 V
CC
(+5V)
23 ROA
2
22 ROA
1
21 TIA
2
20 TIA
1
19 LB
18 N.C.
17 TIB
1
16 TIB
2
15 ROB
1
14 ROB
2
13 V
EE
(-12V)
SP301CS/MR
SP302CS/MR
V
DD
(+12V) 1
RIA
2
2
RIA
1
3
N.C. 4
TOA
2
5
TOA
1
6
SELECT A 7
SELECT B 8
TOB
1
9
TOB
2
10
N.C. 11
RIB
1
12
RIB
2
13
GND 14
28 V
CC
(+5V)
27 N.C.
26 ROA
25 N.C.
24 N.C.
23 TIA
22 LB
21 N.C.
20 TIB
19 N.C.
18 N.C.
17 ROB
16 N.C.
15 V
EE
(-12V)
V
DD
(+12V) 1
RIA
2
2
RIA
1
3
N.C. 4
TOA
2
5
TOA
1
6
SELECT A 7
SELECT B 8
TOB
1
9
TOB
2
10
N.C. 11
RIB
1
12
RIB
2
13
GND 14
28 V
CC
(+5V)
27 ROA
2
26 ROA
1
25 N.C.
24 TIA
2
23 TIA
1
22 LB
21 N.C.
20 TIB
1
19 TIB
2
18 N.C.
17 ROB
1
16 ROB
2
15 V
EE
(-12V)
SP302CT
FEATURES…
The
SP301
and
SP302
are proprietary single-
chip devices that contain both RS-232 and RS-
422 protocol line drivers and receivers. They
differ only in the total number of line drivers and
receivers of each protocol that may be active at
any given time. Their configuration may be
changed at any time by logic levels on two
control lines. In any configuration, both the
SP301
and
SP302
fully meet the requirements
of the EIA RS-232D and RS-422 data commu-
nication standards.
The RS-232 line driver circuits convert TTL
logic level inputs into inverted RS-232 output
signals. The RS-422 line drivers convert TTL
logic levels into RS-422 differential output sig-
nals. The RS-422 line driver outputs feature
high source and sink current capability. All line
drivers are internally protected against short
circuits on their outputs.
The RS-232 receivers convert the EIA RS-232
input signals to inverted TTL output logic levels.
SP301CT
The RS-422 receivers convert the EIA RS-422
differential input signals into non-inverted TTL
output logic levels. Receiver input filtering pro-
vides excellent high frequency noise immunity.
Input pulses with widths less than 1µs are com-
pletely ignored. The RS-232 receivers have the
additional feature of voltage hysteresis, which
helps eliminate spurious output transitions that
might result from low amplitude noise voltages
during slower-speed signal transitions.
A loopback test mode is provided that puts the
driver outputs to a high impedance tri-state
level, and routes the driver outputs to their
associated receiver inputs. In this configuration,
the signal path is non-inverting from the TTL
driver input to the receiver TTL output. This
operating mode allows the controlling system to
perform diagnostic self-test of the RS-232/RS-
422 driver/receiver circuitry at speeds up to
3,000 bits per second.
The
SP301
and
SP302
are available in 24-pin
single–width (0.300") plastic DIP and 28-pin
54
Corporation
SIGNAL PROCESSING EXCELLENCE
V
DD
V
DD
V
CC
V
CC
3.3kΩ
SP301/302
GND
V
EE
V
EE
3.3kΩ
2N2222
Q
3
Q
4
a)
b)
V
DD
V
DD
V
CC
V
CC
3.3kΩ
SP301/302
GND
V
DD
V
EE
V
CC
V
EE
circuitry. If the potential exists for momentary
shorts to voltages greater than
±20V,
it is recom-
mended that a 220Ω resistor be wired in series
with each driver output. This will limit any
damage from the higher short-circuit current
from these higher voltage potentials. Voltage
clamps such as back-to-back Zener diodes can
be used to clamp the driver outputs to “safe”
levels. Short circuit current to ground is inter-
nally limited, and can therefore be sustained
infinitely. Under normal operating conditions,
the drivers can typically source 7mA at
±5V
output, which exceeds the minimum RS-232
standards requirement.
If an
SP301/302
transmitter output occupies a
data transmission line with other RS-232 de-
vices which are not powered by the same power
supplies, it is possible that a device that is not
powered will have a low impedance path to
ground at its driver output. The RS-232 stan-
dards require that with no power applied to the
device, the impedance from a transmitter output
to ground must be greater than 300Ω. This can
be easily achieved as shown in
Figure 1a,
where
an external transistor is used as a switch to
V
DD
SP301/302
3.3kΩ
2N2222
Q
3
Q
4
GND
V
EE
Figure 1. Isolating SP301/302 From Ground;
a) Single SP301/302; b) Multiple SP301/302
SOIC packages for operation over the commercial
temperature range.
USING THE SP301/302
POWER SUPPLIES
The
SP301/SP302
require
±12V
and +5V for
full RS-232 and RS-422 operation. The
±12V
supplies set up the RS-232
±9V
voltage swings,
and the +5V is used for the internal logic that
formats the communications mode and controls
the loopback function. The supply voltages can
be decreased to as low as
±7V
for V
DD
and V
EE
,
and 4.0V for V
CC
. Under these supply condi-
tions, derated performance can be expected.
POWER SUPPLY SEQUENCING
There are two requirements for power supply
sequencing for the
SP301/302.
The first is that
V
DD
is always greater than V
CC
. The second is
that when the part is powered up, V
DD
must be
applied 20ms before V
CC
.
GENERAL USAGE
RS232 Operation
The
SP301
and
SP302
are fully compliant
RS-232 devices. Their outputs are fully pro-
tected against shorts to
±20V
with no external
V
DD
3.3kΩ
GND
3.3kΩ
V
CC
V
EE
V
CC
V
EE
SELECT A = 1
SP302
2N2222
Q
3
Q
4
TIB
1
SELECT B = 0
LOOPBACK = 1
TOB
1
TIB
2
TOB
2
TOA
1
TOA
2
TIA
1
ROB
1
RIB
1
ROB
2
RIB
2
RIA
1
RIA
2
ROA
1
Figure 2. Typical Circuit
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SIGNAL PROCESSING EXCELLENCE