AD7306JR [ADI]

+5 V Powered RS-232/RS-422 Transceiver; + 5V供电的RS - 232 / RS - 422收发器
AD7306JR
型号: AD7306JR
厂家: ADI    ADI
描述:

+5 V Powered RS-232/RS-422 Transceiver
+ 5V供电的RS - 232 / RS - 422收发器

文件: 总8页 (文件大小:152K)
中文:  中文翻译
下载:  下载PDF数据表文档文件
+5 V Powered  
RS-232/RS-422 Transceiver  
a
AD7306  
FEATURES  
RS-232 and RS-422 on One Chip  
Single +5 V Supply  
FUNCTIO NAL BLO CK D IAGRAM  
0.1 F Capacitors  
1
2
24  
23  
22  
21  
20  
19  
18  
17  
16  
V+  
C1+  
C1–  
V–  
Short Circuit Protection  
Excellent Noise Im m unity  
Low Pow er BiCMOS Technology  
High Speed, Low Skew RS-422 Operation  
–40؇C to +85؇C Operations  
C2–  
C2+  
R2  
3
R2  
4
IN  
OUT  
T1  
5
T1  
T2  
OUT  
OUT  
IN  
APPLICATIONS  
DTE-DCE Interface  
Packet Sw itching  
Local Area Netw orks  
Data Concentration  
T2  
6
AD7306  
SOIC  
IN  
V
7
CC  
GND  
R1  
TOP VIEW  
(Not to Scale)  
R1 (B)  
IN  
8
OUT  
R1 /R1 (A)  
Data Multiplexers  
Integrated Services Digital Netw ork (ISDN)  
T3  
IN  
9
IN  
IN  
OUT  
OUT  
T3  
T3  
(B)  
(A)  
NC  
10  
11  
12  
15 232/422 SEL  
14  
13  
GND  
NC  
GENERAL D ESCRIP TIO N  
T he AD7306 line driver/receiver is a 5 V monolithic product  
which provides an interface between T T L signal levels and dual  
standard EIA RS-232/RS-422 signal levels. T he part contains  
two RS-232 drivers, one RS-422 driver, one RS-232 receiver,  
and one receiver path which can be configured either as RS-232  
or as RS-422.  
NC = NO CONNECT  
T he RS-232 channels are suitable for communications rates up  
to 100 kHz and the RS-422 channels are suitable for high speed  
communications up to 5 MHz. T he RS-422 transmitter comple-  
mentary outputs are closely matched and feature low timing  
skew between the complementary outputs. T his is often an es-  
sential requirement to meet tight system timing specifications.  
An internal charge pump voltage converter facilitates operation  
from a single +5 V power supply. T he internal charge pump  
generates ±10 V levels allowing RS-232 output levels to be de-  
veloped without the need for external bipolar power supplies.  
All inputs feature ESD protection, all driver outputs feature  
high source and sink current capability and are internally pro-  
tected against short circuits on the outputs. An epitaxial layer is  
used to guard against latch-up.  
A highly efficient charge pump design allows operation using  
non polarized, miniature 0.1 µF capacitors. T his gives a consid-  
erable saving in printed circuit board space over conventional  
products which can use up to 10 µF capacitors. T he charge  
pump output voltages may also be used to power external cir-  
cuitry which requires dual supplies.  
T he part is available in a 24-lead SOIC and 24-pin plastic DIP  
package.  
REV. B  
Inform ation furnished by Analog Devices is believed to be accurate and  
reliable. However, no responsibility is assum ed by Analog Devices for its  
use, nor for any infringem ents of patents or other rights of third parties  
which m ay result from its use. No license is granted by im plication or  
otherwise under any patent or patent rights of Analog Devices.  
One Technology Way, P.O. Box 9106, Norw ood, MA 02062-9106, U.S.A.  
Tel: 617/ 329-4700  
Fax: 617/ 326-8703  
MIN to  
AD7306–SPECIFICATIONS (TV = +5 V ؎ 5%, C1 = C2 = C3 = C4 = 0.1 F. All specifications T  
CC  
MAX unless otherwise noted.)  
P aram eter  
Min  
Typ  
Max  
Units  
Test Conditions/Com m ents  
RS-232 DRIVER  
T T L Input Logic Low, VINL  
T T L Input Logic High, VINH  
Input Logic Current  
RS-232 High Level Output Voltage  
RS-232 Low Level Output Voltage  
Output Short Circuit Current  
Slew Rate  
0.8  
V
V
µA  
V
V
mA  
V/µs  
V/µs  
2.0  
0.1  
7.3  
–6.5  
±12  
20  
±10  
VIN = 0 V to VCC  
RL = 3 kΩ  
RL = 3 kΩ  
VOUT = 0 V, TA = 0°C to +70°C  
CL = 50 pF, RL = 3 kΩ  
CL = 2500 pF, RL = 3 kΩ  
VCC = 0 V, VOUT = ±3 V  
5.0  
–5.0  
±5  
8
30  
4
Output Resistance (Powered Down)  
300  
10M  
RS-232 RECEIVER  
Input Voltage Range  
–15  
0.8  
+15  
V
V
V
V
kΩ  
V
RS-232 Input T hreshold Low  
RS-232 Input T hreshold High  
RS-232 Input Hysteresis  
RS-232 Input Resistance  
T T L Output Voltage Low, VOL  
T T L Output Voltage High, VOH  
1.3  
1.7  
0.4  
5
0.2  
4.8  
2.4  
1.0  
7
0.1  
3
0.4  
IOUT = +4 mA  
IOUT = –4 mA  
3.5  
V
RS-422 DRIVER  
T T L Input Logic Low, VINL  
T T L Input Logic High, VINH  
Logic Input Current  
0.8  
V
V
µA  
V
V
2.0  
2
0.1  
±10  
5.0  
VIN = 0 V to VCC  
VCC = 5 V, RL Diff = ; Figure 3  
RL Diff = 100 ; Figure 3  
Differential Output Voltage  
Common-Mode Output Voltage  
| VOUT | for Complementary O/P States  
Output Short Circuit Current  
3
0.2  
150  
V
V
mA  
RL Diff = 100 Ω  
0 V VCMR +7 V  
35  
RS-422 RECEIVER  
Common-Mode Voltage Range  
Differential Input T hreshold Voltage  
Input Voltage Hysteresis  
Input Resistance  
T T L Output Voltage Low, VOL  
T T L Output Voltage High, VOH  
±7  
+0.2  
V
V
mV  
kΩ  
V
T ypical RS-422 Input Voltage <5 V  
VCM = 0 V  
–0.2  
3
70  
5
0.2  
4.8  
7
0.4  
IOUT = +4.0 mA  
IOUT = –4.0 mA  
3.5  
V
232/422 SEL Input  
Input Logic Low, VINL  
Input Logic High, VINH  
Logic Input Current  
0.8  
V
V
µA  
2.0  
0.1  
10  
±10  
VIN = 0 V to VCC  
Outputs Unloaded  
POWER SUPPLY CURRENT  
ICC  
15  
mA  
CHARGE PUMP VOLT AGE GENERAT OR  
V+ Output Voltage  
9
V
V
µs  
RS-232 Output Unloaded;  
See T ypical Performance Curves  
RS-232 Outputs Unloaded;  
See T ypical Performance Curves  
V– Output Voltage  
–9  
200  
Generator Rise T ime  
Specifications subject to change without notice.  
–2–  
REV. B  
AD7306  
(V = +5 V ؎ 5%, C1 = C2 = C3 = C4 = 0.1 F. All specifications TMIN to T  
CC  
MAX  
TIMING SPECIFICATIONS  
P aram eter  
unless otherwise noted.)  
Typ  
Max  
Units Test Conditions/Com m ents  
RS-422 Driver  
Propagation Delay Input to Output TPLH, T PHL  
RS-422 O/P to O/P TSKEW  
Driver Rise/Fall T ime TR, TF  
RS-422 Receiver  
35  
2
15  
100  
10  
40  
ns  
ns  
ns  
RL Diff = 100 . CL1 = CL2 = 100 pF, Figures 2 & 4  
RL Diff = 100 . CL1 = CL2 = 100 pF, Figures 2 & 4  
RL Diff = 100 . CL1 = CL2 = 100 pF, Figures 2 & 4  
Propagation Delay Input to Output TPLH, T PHL  
RS-232/RS-422 Enable  
70  
200  
ns  
CL = 15 pF. Figure 5  
RS-232 Disable to RS-422 Enable TEN1  
RS-422 Disable to RS-232 Enable TEN2  
T ransmission Rate (RS-422)  
70  
70  
5
200  
200  
ns  
ns  
MHz  
Figure 6  
Figure 6  
RS-232 Receiver  
Propagation Delay Input to Output  
T ransmission Rate (RS-232)  
1000  
100  
20  
ns  
kHz  
kHz  
CL = 50 pF  
CL = 2.5 nF  
ABSO LUTE MAXIMUM RATINGS*  
(TA = +25°C unless otherwise noted)  
Short Circuit Duration  
T OUT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous  
Power Dissipation  
Small Outline . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 mW  
DIP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 650 mW  
Operating T emperature Range  
VCC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +7 V  
V+ . . . . . . . . . . . . . . . . . . . . . . . . . . . (VCC –0.3 V) to +13.2 V  
V– . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3 V to –13.2 V  
Inputs  
Commercial (J Version) . . . . . . . . . . . . . . . . . 0°C to +70°C  
Industrial (A Version) . . . . . . . . . . . . . . . . –40°C to +85°C  
Storage T emperature Range . . . . . . . . . . . . –65°C to +150°C  
Lead T emperature (Soldering, 10 secs) . . . . . . . . . . . +300°C  
T 1IN, T 2IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . V– to V+  
T 3IN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to V+  
R1IN A/B, R2IN . . . . . . . . . . . . . . . . . . . . . . . –25 V to +25 V  
232/422 SEL . . . . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to V+  
Outputs  
T 1OUT , T 2OUT . . . . . . . . . . . . . . . . . . . . . . . –15 V to +15 V  
T 3OUT (A), (B) . . . . . . . . . . . . . . . . . . . . . . . –0.3 V to +7 V  
R1OUT , R2OUT . . . . . . . . . . . . . . . . –0.3 V to (VCC + 0.3 V)  
*Stresses above those listed under “Absolute Maximum Ratings” may cause  
permanent damage to the device. T his is a stress rating only and functional  
operation of the device at these or any other conditions above those listed in the  
operational sections of this specification is not implied. Exposure to absolute  
maximum ratings for extended periods of time may affect device reliability.  
CAUTIO N  
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily  
accumulate on the human body and test equipment and can discharge without detection.  
Although the AD7306 features proprietary ESD protection circuitry, permanent damage may  
occur on devices subjected to high energy electrostatic discharges. T herefore, proper ESD  
precautions are recommended to avoid performance degradation or loss of functionality.  
WARNING!  
ESD SENSITIVE DEVICE  
O RD ERING GUID E  
Model  
Tem perature Range P ackage D escription  
P ackage O ption  
AD7306JR  
AD7306JN  
AD7306AR  
AD7306AN  
0°C to +70°C  
0°C to +70°C  
–40°C to +85°C  
–40°C to +85°C  
24-Lead SOIC  
24-Pin DIP  
24-Lead SOIC  
24-Pin DIP  
R-24  
N-24  
R-24  
N-24  
–3–  
REV. B  
AD7306  
P IN FUNCTIO N D ESCRIP TIO N  
SO IC D IP  
P in  
P in  
Mnem onic  
Function  
1
19  
V+  
Internally Generated Positive Supply (+9 V nominal). A 0.1 µF capacitor must be connected  
between this pin and GND.  
2, 3  
4
20, 22  
C1+, C1–  
R2IN  
External Capacitor 1 T erminals. A 0.1 µF capacitor must be connected between these pins.  
RS-232 Receiver R2 Input. T his input accepts RS-232 input voltages.  
RS-232 T ransmitter (Driver) T 1 Output (T ypically ±7.5 V).  
RS-232 T ransmitter (Driver) T 2 Output (T ypically ±7.5 V).  
Power Supply Input (5 V ± 5%).  
23  
24  
1
5
T 1OUT  
6
T 2OUT  
7
2
VCC  
8
3
R1IN (B)  
R1IN/R1IN (A)  
RS-422 Receiver R1, Differential Input B.  
9
4
Receiver R1 Input. May be configured to accept either single ended RS-232 levels or  
differential RS-422 levels. It is configured using the 232/422 SEL pin.  
10  
11  
5
6
T 3OUT (B)  
T 3OUT (A)  
NC  
RS-422 T ransmitter (Driver) T 3, Differential Output B.  
RS-232 T ransmitter (Driver) T 3, Differential Output A.  
No Connect Pins.  
12, 13 16, 21  
14, 18 7, 11  
GND  
Ground Pin. Must be connected to 0 V.  
15  
8
232/422 SEL  
Select Input. T his input configures Receiver R1 to accept either RS-232 or RS-422 signal lev-  
els. A Logic 1 on this input selects 232 operation while a Logic 0 selects 422 operation.  
16  
17  
19  
20  
21  
9
T 3IN  
T T L/CMOS Input to the RS-422 T ransmitter T 3.  
T T L/CMOS Output from Receiver R1.  
10  
12  
13  
14  
R1OUT  
T 2IN  
T T L/CMOS Input to RS-232 T ransmitter T 2.  
T 1IN  
T T L/CMOS Input to RS-232 T ransmitter T 1.  
R2OUT  
C2+, C2–  
V–  
T T L/CMOS Output from Receiver R2.  
22, 23 15, 17  
24 18  
External Capacitor 2 T erminals. A 0.1 µF capacitor must be connected between these pins.  
Internally Generated Negative Supply (–9 V nominal). A 0.1 µF capacitor must be connected  
between this pin and GND.  
P IN CO NFIGURATIO NS  
SO IC  
D IP  
1
2
3
4
5
24  
V+  
V–  
T2  
1
2
24  
T1  
OUT  
OUT  
23  
22  
21  
20  
19  
18  
17  
16  
C1+  
C2–  
23 R2  
V
IN  
CC  
C2+  
C1–  
3
22  
21  
20  
19  
18  
17  
C1–  
R1 (B)  
IN  
R2IN  
R2OUT  
T1IN  
R1 /R1 (A)  
4
NC  
IN  
IN  
OUT  
OUT  
T1OUT  
T3  
T3  
(B)  
(A)  
5
C1+  
T2IN  
T2OUT  
VCC  
6
7
AD7306  
SOIC  
TOP VIEW  
(Not to Scale)  
6
AD7306  
DIP  
TOP VIEW  
(Not to Scale)  
V+  
V–  
GND  
7
GND  
R1OUT  
R1IN (B)  
8
8
232/422 SEL  
C2–  
R1IN /R1IN (A)  
T3OUT(B)  
T3IN  
9
T3  
IN  
9
16 NC  
15  
14 R2  
10  
11  
12  
15 232/422 SEL  
R1  
10  
11  
12  
C2+  
OUT  
T3OUT(A)  
14  
13  
GND  
NC  
GND  
OUT  
IN  
NC  
T2  
IN  
13  
T1  
NC = NO CONNECT  
NC = NO CONNECT  
REV. B  
–4–  
AD7306  
3V  
+5V INPUT  
7
0.1µF  
1.5V  
1.5V  
0V  
V
tPHL  
CC  
tPLH  
2
0.1µF  
0.1µF  
1
C1+  
V+  
V–  
±10V  
POWER  
SUPPLY  
T3  
T3  
(A)  
0.1µF  
0.1µF  
OUT  
OUT  
3
C1–  
C2+  
C2–  
1/2 VO  
22  
23  
VO  
24  
GENERATOR  
(B)  
tSKEW  
tSKEW  
20  
19  
16  
5
6
T1  
T1  
T2  
T3  
T1  
IN  
IN  
IN  
OUT  
OUT  
VO  
0V  
90% POINT  
90% POINT  
RS-232  
OUTPUTS  
TTL/CMOS  
INPUTS  
T2  
T2  
T3  
10% POINT  
10% POINT  
–VO  
10  
11  
RS-422  
OUTPUT  
tR  
tF  
T3  
T3  
(B)  
OUT  
OUT  
(A)  
AD7306  
Figure 4. RS-422 Driver. Propagation Delay Rise/Fall  
Tim ing  
21  
17  
4
9
8
RS-232  
INPUT  
R2  
R2  
R2  
R1  
IN  
OUT  
OUT  
TTL/CMOS  
OUTPUTS  
RS-232/  
RS-422  
INPUT  
R1  
2.5V  
(A)  
R1 /R1  
IN  
IN  
DIFFERENTIAL  
INPUT  
0V  
0V  
R1 (B) - R1 (A)  
RS-422  
INPUT  
IN IN  
R1 (B)  
IN  
15  
–2.5V  
232/422 SEL  
tPHL  
tPLH  
18  
14  
V
OH  
R1  
OUT  
V
OL  
Figure 1. AD7306 Application Circuit  
T3  
(B)  
OUT  
Figure 5. RS-422 Receiver Tim ing  
C
C
= 100pF  
= 100pF  
L1  
L2  
RL  
= 100  
T3  
T3  
IN  
DIFF  
232/422 SEL  
1.5V  
1.5V  
T3  
(A)  
OUT  
tEN1  
tEN2  
Figure 2. RS-422 Driver. Propagation Delay Test Circuit  
V
OH  
V
OH  
R1  
OUT  
T3  
(B)  
OUT  
V
V
OL  
OL  
RS-232  
RS-232  
RS-422  
V
T3  
T3  
OD  
RL  
DIFF  
IN  
Figure 6. RS-232/RS-422 Receiver Enable Tim ing  
T3  
(A)  
OUT  
Figure 3. RS-422 Driver. Voltage Measurem ent Test  
Circuit  
–5–  
REV. B  
AD7306  
RS-232 D r iver s  
GENERAL D ESCRIP TIO N  
T he RS-232 drivers in the AD7306 meet the EIA RS-232  
specifications. T he drivers are inverting level shifters which  
convert T T L/CMOS levels into RS-232 output levels. T he in-  
put switching threshold is typically 1.3 V. With a typical  
RS-232 load, the output levels are ±7.5 V. Under worst case  
load conditions, the drivers are guaranteed to provide ±5 V  
which meets the minimum RS-232 requirement. T he output  
slew rate is internally limited to <30 V/µs without the need for  
an external slew limiting capacitor. Short circuit protection is  
also provided which prevents damage in the event of output  
fault conditions. Active current limiting is used which limits the  
output short circuit current to less than 12 mA in the event of  
an output fault. T his type of current limiting does not degrade  
the output voltage swing under normal loading conditions as  
would be the case with conventional passive limiting.  
T he AD7306 drivers/receivers provide an interface which is  
compatible with RS-232/RS-422 standard interfaces. As both  
standards are widely accepted it is often necessary to provide an  
interface which is compatible with both. T he AD7306 is ideally  
suited to this type of application as both standards may be met  
using a single package. T his part contains two RS-232 drivers,  
one RS-422 driver, one RS-232 receiver, and one receiver path  
which can be configured as either RS-232 or RS-422. T his re-  
ceiver is configured using the 232/422 SEL pin.  
T his part also contains an internal charge pump voltage con-  
verter which facilitates operation using a single +5 V power  
supply.  
Char ge P um p D C-D C Voltage Gener ator  
T he charge pump voltage generator uses a switched capacitor  
technique to develop ±10 V levels from an input +5 V supply. A  
highly efficient charge pump design coupled with a high fre-  
quency internal oscillator permit operation using four 0.1 µF  
capacitors.  
T he powered-down output impedance is typically 10 M. T his  
is considerably larger than the 300 minimum value required  
by the RS-232 specification. It provides additional protection  
under fault conditions where another powered-up transmitter  
output is inadvertently shorted to the powered-down device.  
+10V  
OUTPUT  
V+  
C3  
±10V  
POWER SUPPLY  
GENERATOR  
RS-232 Receiver s  
+5V  
INPUT  
SUPPLY  
0.1µF  
T he receivers are inverting level shifters which accept RS-232  
input levels (±3 V to ±15 V) and translates them into 5 V  
T T L/CMOS levels. T he input switching thresholds are 0.8 V  
minimum and 2.4 V maximum which are well within the  
RS-232 requirement of ±3 V. Internal 5 kpull-down resistors  
to GND are provided on the receiver inputs. T his ensures that  
an unconnected input will be interpreted as a low level giving a  
Logic “1” on the T T L/CMOS output. Excellent noise immu-  
nity is achieved by the use of hysteresis and internal filtering  
circuitry. T he filter rejects noise glitches of up to 0.5 µs in  
duration.  
V
CC  
–10V  
OUTPUT  
V–  
C2–  
C4  
0.1µF  
C1–  
C2+  
C1+  
C1  
0.1µF  
C2  
0.1µF  
Figure 7. Charge Pum p Voltage Generator  
Capacitors C1 and C2 act as charge storage capacitors while C3  
and C4 provide output smoothing. For correct operation all four  
capacitors must be included. Either polarized or nonpolarized  
capacitors may be used for C1–C4. If a polarized type is used,  
then the correct polarity should be observed. T his may be ig-  
nored with nonpolarized type capacitors.  
RS-422 D r iver  
T he RS-422 driver on the AD7306 accepts a T T L/CMOS in-  
put and translates it into a differential RS-422 level signal. T he  
input switching threshold is typically 1.3 V. T he unloaded out-  
put differential voltage is typically ±5 V (see T ypical Perfor-  
mance Characteristics). Short circuit protection is provided on  
the output which limits the current to less than 150 mA.  
T he charge pump output voltages, V+ and V–, are used inter-  
nally to power the RS-232 transmitters. T his permits RS-232  
output levels to be developed on the RS-232 transmitter out-  
puts. T he charge pump output voltages may also be used to  
power external circuitry if the current requirements are small.  
Please refer to the T ypical Performance Characteristics.  
RS-422 Receiver  
T he RS-422 receiver on the AD7306 accepts a differential in-  
put signal and translates it into a T T L/CMOS output level.  
T he input resistance on both differential inputs is 5 ktypical.  
With the receiver inputs unconnected (floating), internal bias-  
ing ensures that the receiver output is a Logic “1.”  
T he generator rise time after power up is 200 µs typical. T his  
time is necessary to completely charge the storage capacitors in  
the charge pump. T herefore, RS-232 data transmission should  
not be initiated until this time has elapsed after switch on. T his  
will ensure that valid data is always transmitted.  
Excellent noise immunity and high transmission speed is  
achieved using the differential configuration.  
REV. B  
–6–  
Typical Performance Characteristics–AD7306  
10  
8
10  
V+  
+V CURRENT  
E
8
V-  
–V CURRENT  
E
6
6
4
2
0
V
= 5V  
CC  
4
T + 25°C  
2
0
5
10  
15  
20  
25  
30  
0
0
2
4
6
8
10  
RS-232 TRANSMITTER OUTPUT CURRENT – mA  
OUTPUT CURRENT ± – mA  
Figure 11. RS-232 Driver Output Voltage vs. Current  
Figure 8. V+ and V– Voltage vs. Current  
6
25  
20  
15  
10  
5
V
= 5.25V  
CC  
+V  
E
5
4
3
2
1
0
–V  
E
V
= 5.0V  
CC  
V
= 4.75V  
CC  
0
0
10  
20  
30  
40  
50  
60  
500  
1000  
1500  
2000  
2500  
0
DIFFERENTIAL O/P CURRENT – mA  
LOAD CAPACITANCE – pF  
Figure 12. RS-422 Driver Output Current vs. Output Voltage  
Figure 9. RS-232 Driver Slew Rate vs. Load Capacitance  
A3  
2 4 V  
A4 -0 370 V  
100  
90  
100  
90  
10  
10  
0%  
0%  
5
1V  
1V  
5V  
5V  
1µs  
10ns  
Figure 13. RS-422 Driver; RLDIFF = 100 , CL1 = CL2 = 100 pF  
Figure 10. RS-232 Driver; RL = 5 k, CL = 50 pF  
REV. B  
–7–  
AD7306  
Single-Ended D ata Tr ansm ission  
D iffer ential D ata Tr ansm ission  
Single-ended interfaces are used for low speed, short distance  
communications such as from a computer terminal to a printer.  
A single line is used to carry the signal. Various standards have  
been developed to standardize the communication link, the most  
popular of these being the RS-232. T he RS-232 standard was  
introduced in 1962 by the EIA and has been widely used  
throughout the industry. T he standard has been revised several  
times, and the current revision is known as EIA-232E. T he  
RS-232 standard is suitable for single-ended data transmission  
at relatively slow data rates over short distances. A typical  
RS-232 interface is shown in Figure 14.  
When transmitting at high data rates, over long distances and  
through noisy environments, single-ended data transmission is  
often inadequate. In this type of application, differential data  
transmission offers superior performance. Differential transmis-  
sion uses two signal lines to transmit data. It rejects ground  
shifts and is insensitive to noise signals which appear as com-  
mon mode voltages on the transmission lines. T o accommodate  
faster data communication, the differential RS-422 standard was  
developed. T herefore, it can be used to reliably transmit data at  
higher speeds and over longer distances than single-ended trans-  
mission. A typical RS-422 interface is shown in Figure 15.  
DATA  
OUT  
DATA  
IN  
DATA  
IN  
DATA  
OUT  
RS-422 CHANNEL  
RX  
RX  
TX  
TX  
RS-232 CHANNEL  
Figure 15. Differential RS-422 Interface  
Figure 14. Single-Ended RS-232 Interface  
Table I. Com parison of RS-232 and RS-422 Interface Standards  
Specification  
EIA-232E  
RS-422  
T ransmission T ype  
Maximum Data Rate  
Single-Ended  
20 kB/s  
Load Dependent  
±5 V  
30 V/µs max  
3 kto 7 kΩ  
±3 V  
±15 V  
1
1
Differential  
10 MB/s  
4000 ft.  
Maximum Cable Length  
Minimum Driver Output Voltage  
Slew Rate  
Receiver Input Resistance  
Receiver Input Sensitivity  
Receiver Input Voltage Range  
No. of Drivers per Line  
No. of Receivers per Line  
±1.5 V  
4 kmin  
±200 mV  
±7 V  
1
10  
O UTLINE D IMENSIO NS  
D imensions shown in inches and (mm).  
24-Lead P in P lastic D IP (N-24)  
24-Lead SO IC (R-24)  
0.6141 (15.60)  
0.5985 (15.20)  
0.260 ± 0.001  
(6.61 ± 0.03)  
24  
13  
0.32 (8.128)  
0.30 (7.62)  
1.228 (31.19)  
1.226 (31.14)  
1
12  
0.130 (3.30)  
0.128 (3.25)  
SEATING  
PLANE  
0.011 (0.28)  
0.009 (0.23)  
PIN 1  
0.1043 (2.65)  
0.0926 (2.35)  
0.0291 (0.74)  
x 45°  
0.0098 (0.25)  
0° - 15°  
0.02 (0.5)  
0.016 (0.41)  
0.11 (2.79)  
0.09 (2.28)  
0.07(1.78)  
0.05 (1.27)  
0.0500 (1.27)  
0.0157 (0.40)  
8°  
0°  
0.0500  
(1.27)  
BSC  
0.0192 (0.49)  
0.0138 (0.35)  
0.0118 (0.30)  
0.0040 (0.10)  
NOTES  
SEATING  
PLANE  
0.0125 (0.32)  
0.0091 (0.23)  
1.  
2.  
LEAD NO. 1 IDENTIFIED BY DOT OR NOTCH.  
PLASTIC LEADS WILL BE EITHER SOLDER DIPPED OR TIN LEAD PLATED  
IN ACCORDANCE WITH MIL-M-385 10 REQUIREMENTS.  
REV. B  
–8–  

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