SIPEX SP304CT

SP304
Corporation
SIGNAL PROCESSING EXCELLENCE
RS-232/RS-422 Line Drivers/Receivers
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■
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RS-232 and RS-422 on One Chip
Multiple Drivers and Receivers
Software-selectable Modes
Loopback for Self-Testing
Short-circuit Protected
Single-width 24-pin DIP and 28–pin
SOIC Packages
DESCRIPTION…
The SP304 is an enhanced-performance version of the Sipex SP302 RS-232 and RS-422
protocol line drivers and receivers. It is pin-for-pin compatible with the SP302, and in any
configuration, fully meets the requirements of the EIA RS-232D and RS-422 data communication
standards. A loopback test mode is provided.The SP304 is available in 24-pin single width plastic
DIP, and 28-pin SOIC packages for commercial and industrial temperature range operation.
TOB1
TOB2
TOA1 TOA2
RIB1
RIB2
RIA1 RIA2
VDD
VCC
VEE
GND SELECT
A
B
SP304
LOOP–
BACK
TIB1
Corporation
SIGNAL PROCESSING EXCELLENCE
TIB2
TIA1
ROB1
ROB2
ROA1
77
SPECIFICATIONS
(TMIN ≤ TA ≤ TMAX and nominal supply voltages unless otherwise noted)
PARAMETER
RS-232 DRIVER
TTL Input Level
V
V
High Level Output
Low Level Output
Short Circuit Current
Loopback Output Voltage
Slew rate
IL
IH
MIN.
TYP.
0
2.0
+5.0
Transition Time
MAX.
0.8
-5.0
±30
-1.5
30
+15
+2.5
+1.35
7
0.4
OH
0.8
IL
IH
6.0
1.0
±6
±100
±500
400
±7
±15
+0.2
0.4
OL
OH
DD
CC
EE
78
V
V
V
V
mA
V
V/µs
R = 3kΩ, V = 0.8V
R = 3kΩ, V = 2.0V
V = 0V
R = 3kΩ, V = -12.0V; Note 1
C = 50pF, R = 3kΩ; T =
25°C
V from +3V to -3V
or -3V to +3V
L
IN
L
IN
OUT
L
EE
L
L
A
OUT
kbps
OL
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
V
2.4
Maximum Receiving Rate
1,000
Short Circuit Output Current
POWER REQUIREMENTS
V = +12V, ±10%
V = +5V, ±10%
V = -12V, ±10%
ENVIRONMENTAL
Operating Temperature
-CS
0
-MR
-55
Storage Temperature
-65
CONDITIONS
µs
3
Maximum Transmission Rate 200
RS-232 RECEIVER
Input Voltage Range
-15
Input High Threshold
+1.75
Input Low Threshold
+0.75
Input Impedance
3
TTL Output Level
V
V
2.4
Maximum Receiving Rate
200
RS-422 DRIVER
TTL Input Level
V
0
V
2.0
High Level Output
2.75
Low Level Output
Differential Output
±2
UNITS
±120
7
5
11
V
V
V
kΩ
V
V
kbps
V
V
V
V
V
V
mA
µA
ns
kbps
V
V
V
mV
kΩ
V
V
kbps
mA
15
7
20
mA
mA
mA
+70
+125
+150
°C
°C
°C
Note 6
Positive-going
Negative-going
V = +4.75V, I = +1.6mA
V = +4.75V, I = -0.5mA
CC
OUT
CC
OUT
I = -20mA
I = +20mA
R = 100Ω
R =∞
Note 2
-0.25V ≤ V ≤ 6V; power off
R = 100Ω, C = 15pF; Note 3
OH
OL
L
L
O
L
L
Note 4
Note 4
T = 25°C
V = 0V; T = 25°C
-7V ≤ V ≤ +7V
A
CM
A
CM
V = +4.75V, I = +1.6mA
V = +4.75V, I = -0.5mA
CC
OUT
CC
OUT
V = 0V
OUT
Note 5
Note 5
Note 5
Corporation
SIGNAL PROCESSING EXCELLENCE
Notes:
1.
2.
3.
4.
5.
In Loopback 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 SP304 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;
RS232 loads 3kΩ, 2500pF, 20kHz; RS422 outputs across 100Ω, 500kHz.
IN
A
IL
TYPICAL PERFORMANCE CURVES
RS-232 Driver
T IN
RS-232 Receiver
5V
GND
10V
RIN
5V
GND
–5V
T OUT
ROUT 5V
GND
GND
–10V
20kHz
20kHz
RS-422 Driver
RS-422 Receiver
2V
RIN
TIN
GND
TOUT 5V
GND
ROUT 5V
GND
–5V
500kHz
Corporation
SIGNAL PROCESSING EXCELLENCE
2V
GND
–2V
500kHz
79
PIN ASSIGNMENTS
VDD (+12V) 1
RIA2 2
RIA1 3
TOB1 8
TOB2 9
VDD (+12V) 1
RIA2 2
RIA1 3
21 TIA2
N.C. 4
20 TIA1
19 LB
TOA2 5
TOA1 6
18 N.C.
SELECT A 7
17 TIB1
16 TIB2
SELECT B 8
TOB1 9
TOB2 10
RIB1 10
RIB2 11
14 ROB2
GND 12
13 VEE (-12V)
15 ROB1
N.C. 11
RIB1 12
RIB2 13
GND 14
FEATURES…
The SP304 is a proprietary single-chip device
that contain both RS-232 and RS-422 protocol
line drivers and receivers. It is pin–for–pin compatible with the Sipex SP302. Like the SP302,
its configuration may be changed at any time by
logic levels on two control lines. In any configuration, the SP304 fully meets the requirements
of both the EIA RS-232D and RS-422 data
communication standards. The SP304 enhancements include improved isolation from external
signals and a true high–impedance driver output
in the loopback test mode, and no power up
sequence requirements.
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 signals. 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. The RS-422 receivers convert the EIA RS422 differential input signals into non-inverted
TTL output logic levels. Receiver input filtering
provides excellent high frequency noise immunity. Input pulses with widths less than 1µs are
completely ignored. The RS-232 receivers have
the additional feature of voltage hysteresis, which
helps eliminate spurious output transitions that
80
28 VCC (+5V)
27 ROA2
26 ROA1
25 N.C.
24 TIA2
SP304CT
SELECT A 6
SELECT B 7
22 ROA1
SP304CS
TOA2 4
TOA1 5
24 VCC (+5V)
23 ROA2
23 TIA1
22 LB
21 N.C.
20 TIB1
19 TIB2
18 N.C.
17 ROB1
16 ROB2
15 VEE (-12V)
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. In the loopback mode a
±13.2V input range may be applied to the receiver inputs with no interference to the loopback
test. In addition, the driver outputs are in a true
high–impedance state during loopback.
The SP304 is available in 24-pin single width
(0.300") plastic DIP and 28-pin SOIC packages,
for operation over the commercial and industrial temperature ranges.
USING THE SP304
POWER SUPPLIES
The SP304 requires ±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 VDD and V EE, and
Corporation
SIGNAL PROCESSING EXCELLENCE
VDD
VDD
VCC
VCC
SP304
3.3kΩ
GND
VEE
VEE
3.3kΩ
2N2222
Q4
Q3
a) Single SP304
b) Multiple SP304
VDD
VCC
VCC
GND
VEE
VEE
VDD
VCC
VDD
SP304
3.3kΩ
SP304
GND
3.3kΩ
VEE
2N2222
Q3
Q4
Figure 1. Isolating the SP304 from Ground.
+4.0V for VCC. Under these supply conditions,
derated performance can be expected.
transmission line with other RS-232 devices
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 standards 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
isolate an SP304 from ground in the power off
condition. With VDD turned on, the transistor
switch is on, connecting ground (GND) for the
device to the circuit ground. In a power-off
condition, this transistor is switched off, thus
isolating the unit from circuit ground, and thereby
leaving the driver in a high impedance state.
Multiple SP304s can be connected as shown in
Figure 1b.
RS-422 OPERATION
The SP304 is a fully compliant RS-422 device
when operating in the RS-422 mode. Baud rate
and drive capability have been balanced to provide as much versatility as possible. The SP304
is both guaranteed for a 1Mbps data rate,
POWER SUPPLY SEQUENCING
There are no special power–up sequencing requirements for the SP304.
GENERAL USAGE
RS-232 Operation
The SP304 is a fully compliant RS-232 device.
Its outputs are fully protected against shorts to
±20V with no external circuitry. If the potential
exists for momentary shorts to voltages greater
than ±20V, it is recommended 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 backto-back Zener diodes can be used to clamp the
driver outputs to “safe” levels. Short circuit
current to ground is internally 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.
VDD
VDD
3.3KΩ
VCC
VCC
VEE
VEE
SELECT A = 1
GND
3.3KΩ
SP304
2N2222
Q3
Q4
SELECT B = 0
LOOPBACK = 1
TIB1
TOB1
TIB2
TOB2
TIA1
TOA1
TOA2
ROB1
RIB1
ROB2
RIB2
ROA1
RIA1
RIA2
If an SP304 transmitter output occupies a data
Figure 2. Typical Circuit
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SIGNAL PROCESSING EXCELLENCE
81
supplying ±2V minimum into a 100Ω load.
Short circuit protection for the RS-422 operating mode is the same as in the RS-232 mode. The
driver outputs can be shorted to ground for an
infinite duration, with a maximum current of
±100mA.
The RS-422 receivers accept differential signals
at a 1Mbps rate, and translate them to a noninverted TTL output. The receivers are specified with a ±15V differential input voltage,
which means that to operate normally, the difference betweeen the voltages at the inputs
cannot exceed ±15V. The common mode voltage is specified as ±7V. This identifies the
midpoint of the range about which the differential input must lie so that the receiver can detect
a change of state. Within this ±7V range, the
receivers will recognize a change in state with a
±200mV differential threshold voltage. Since
the RS-232 and RS-422 inputs are shared, all
receiver inputs are protected to ±30V to guard
against inadvertently applying an RS-232 signal
to an input that is configured for RS-422.
82
Figure 2 shows a typical circuit for the SP304.
In this case the SP304 is shown configured for
one (1) duplex RS-422 and two (2) duplex
RS-232 communication paths.
CONFIGURING THE SP304
Figures 3, 4 and 5 show the various combinations of simultaneous RS-232 and RS-422
operation that can be achieved with the SP304.
Each of these configurations are software
selectable by logic level on the SELECT A and
SELECT B control lines. Configuration can be
changed “on-the-fly”.
Corporation
SIGNAL PROCESSING EXCELLENCE
FIGURE 3: SP304 CONTROL LOGIC CONFIGURATION
SELECTION
LOGIC VALUE
LOGIC VALUE
LOGIC VALUE
LOGIC VALUE
SELECT A:
SELECT B:
0
0
0
1
1
0
1
1
NON–
LOOPBACK
(LB = 1)
RIA2
ROA2
RIA2
ROA2
RIA1
ROA1
RIA1
ROA1
TOA1
TOA2
RIB2
RIB1
LOOPBACK
(LB=0)
TIA1
TIA2
ROB2
ROB1
TOB1
TIB1
TOB2
TIB2
RIB2
RIB1
TOB1
TOB2
ROA2
RIA2
RIA1
ROA1
RIA1
TIA1
TIA2
ROB1
TIB1
TOA*1
TIA1
TOA*2
TIA2
TOA*2
TIA2
RIB2
ROB2
TOB1
TIB1
TOB2
TIB2
TOA1
TOA2
TIA1
RIB2
ROB2
RIB1
ROB1
TOB1
TIB1
TOB2
TIB2
RIA2
ROA1 RIA1
TIA1
ROB1
RIA2
RIA1
ROA1
TOA1
TOA2
RIB2
RIB1
TOB1
TOB2
ROA2
TOA*1
RS-232 DRIVER
* Tri–state Output
Corporation
TOA2
RIA2
RIB1
SIGNAL PROCESSING EXCELLENCE
TOA1
RIA2
RIA1
RIB2
RIB1
ROB1
TOB*1
TOB*2
TIB1
RS-232 RECEIVER
TOA*1
TOA*2
RIA2
RIA1
ROA1
TOA*1
TIA1 TOA*
2
RIB2
ROB2
RIB1
ROB1
TOB1
TIB1
TOB2
TIB2
ROA1
TIA1
ROB1
TIB1
ROA1
TIA1
RIB2
RIB1
ROB1
TOB*1
TOB*2
TIB1
RS-422 RECEIVER
RS-422 DRIVER
83
FIGURE 4: SP304 CONFIGURATIONS
Four-Channel Duplex RS-232
Four independent channels of RS-232 line driver
and four channels of RS-232 receiver.
TIA1
TOA1
TIA2
TOA2
TIB1
TIB2
Two-Channel Duplex RS-232 &
One-Channel Duplex RS-422
Two RS-232 line drivers and receivers, and a
single RS-422 line driver and receiver.
TIA1
TOA1
TIA2
TOA2
TOB1
TOB2
RS-232 LINE DRIVERS
RS-232 RECEIVERS
RS-232 LINE DRIVERS
RS-232 RECEIVERS
RIA1
ROA1
RIA2
ROA2
RIA1
ROA1
RIA2
ROA2
RIB1
ROB1
SELECT A = 0
SELECT B = 0
LB = 1
84
TOB2
RS-422 LINE DRIVER
RIB2
ROB2
TOB1
TIB1
RS-422 RECEIVER
ROB1
RIB1
RIB2
SELECT A = 0
SELECT B = 1
LB = 1
Corporation
SIGNAL PROCESSING EXCELLENCE
FIGURE 5: SP304 CONFIGURATIONS
Two-Channel Duplex RS-232 &
One-Channel Duplex RS-422
Opposite Drivers
Two-Channel Duplex RS-422
Two RS-422 line drivers and two RS-422
receivers.
Two RS-232 line drivers and receivers, and a
single RS-422 line driver and receiver. At first
glance, this is the same configuration as that in
Figure 4. Note however that functions are activated on the opposite channels.
TOB1
TIB1
TOB2
TIB2
TIA1
TIB1
TOA1
TOA2
TOB1
TOB2
RS-232 LINE DRIVERS
RS-422 LINE DRIVERS
RS-232 RECEIVER
RIB1
ROB1
RS-422 RECEIVERS
ROA1
RIB2
ROB2
RIA1
RIA2
RIB1
ROB1
RIB2
TOA1
TIA1
TOA2
SELECT A = 1
SELECT B = 1
RS-422 LINE DRIVER
RS-422 RECEIVER
ROA1
LB = 1
RIA1
RIA2
SELECT A = 1
SELECT B = 0
LB = 1
Corporation
SIGNAL PROCESSING EXCELLENCE
85
LOOPBACK
The SP304 has a function called loopback, which is
essentially a chip self-test. However, by connecting
system test loops with the inputs and outputs of the
SP304, a system-level diagnostic can be run on
power-up or on command. The test loops can be
enabled and disabled allowing both system test and
operation with the same components. A maximum
data rate for loopback of 3kbps is recommended.
Loopback is a pin-programmable function, activated
by a logic low on the LB pin (19). As shown in these
figures, the loopback function internally con-
SP304 CONFIGURATIONS IN LOOPBACK MODE
Two -Channel Full Duplex RS-232
One-Channel Full Duplex RS-232 &
One-Channel Full Duplex RS-422
TOA1
TIA1
RS-232 LINE DRIVER
RS-232 RECEIVER
ROA1
RIA1
TOB2
TIB1
TOB1
TIA2
TOA2
RS-422 LINE DRIVER
RS-422 RECEIVER
RS-232 LINE DRIVER
ROB1
RS-232 RECEIVER
ROA2
RIA2
TIB1
TOB1
RS-232 RECEIVER
ROB1
RIB1
TIB2
TOB2
RS-232 LINE DRIVER
TOA1
TIA1
RS-232 RECEIVER
ROA1
RIA1
TOA2
TIA2
RS-232 LINE DRIVER
RS-232 RECEIVER
86
RIB2
RS-232 LINE DRIVER
RS-232 LINE DRIVER
RS-232 RECEIVER
RIB2
ROB2
RIB1
ROA2
RIA2
SELECT A = 0
SELECT A = 0
SELECT B = 0
SELECT B = 1
LB = 0 (ACTIVE)
LB = 0 (ACTIVE)
Corporation
SIGNAL PROCESSING EXCELLENCE
nects the driver outputs to the corresponding
receiver inputs, and switches the output pin to a
high impedance from VEE to ground. Receiver
outputs are left active for signal verification.
During loopback, the receiver inputs are tied to
ground via a 5kΩ pulldown resistor. The receiver inputs can accept the full ±15V swings
with no interference to the loopback function.
SP304 CONFIGURATIONS IN LOOPBACK MODE
One-Channel Full Duplex RS-232 &
One-Channel Full Duplex RS-422
Opposite Drivers
TIB2
Two-Channel Full Duplex RS-422
TOB2
TOB2
TIB1
TIB1
TOB1
TOB1
RS-232 LINE DRIVERS
RS-422 LINE DRIVERS
RS-232 RECEIVERS
ROB2
RS-422 RECEIVERS
RIB2
ROB1
RIB1
RIB2
ROB1
RIB1
TOA2
TIA1
TOA1
TOA2
TIA1
TOA1
RS-422 LINE DRIVERS
RS-422 RECEIVERS
ROA1
RS-422 LINE DRIVER
RS-422 RECEIVER
ROA1
RIA1
RIA2
RIA1
RIA2
SELECT A = 1
SELECT B = 1
SELECT A = 1
LB = 0 (ACTIVE)
SELECT B = 0
LB = 0 (ACTIVE)
Corporation
SIGNAL PROCESSING EXCELLENCE
87
ORDERING INFORMATION
Max # of Duplex Channels
Model
RS-232
RS-422
Temperature
Package
SP304CS .................. 4 ...................... 2 .................................... 0˚C to 70˚C ........................ 24-pin Single-Width Plastic DIP
SP304CT .................. 4 ...................... 2 .................................... 0˚C to 70˚C ....................................................... 28-pin SOIC
SP304ES .................. 4 ...................... 2 .................................. -40˚C to 85˚C ....................... 24-pin Single-Width Plastic DIP
SP304ET .................. 4 ...................... 2 .................................. -40˚C to 85˚C ...................................................... 28-pin SOIC
88
Corporation
SIGNAL PROCESSING EXCELLENCE