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(R)
MC1488
RS232C QUAD LINE DRIVER
s s
s
s s
CURRENT LIMITED OUTPUT 10mA TYP. POWER-OFF SOURCE IMPEDANCE 300 MIN. SIMPLE SLEW RATE CONTROL WITH EXTERNAL CAPACITOR FLEXIBLE OPERATING SUPPLY RANGE INPUTS ARE TTL AND P COMPATIBLE
DESCRIPTION The MC1488 is a monolithic quad line driver designed to interface data terminal equipment with data communications equipment in conformance with the specifications of EIA Standard No. RS232C.
P
DIP14 (Plastic Package)
D
SO14 (Plastic Micropackage)
ORDER CODES : MC1488P (Plastic DIP) MC1488D (SO14)
PIN CONNECTIONS (top view)
LOGIC DIAGRAM
March 2000
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ABSOLUTE MAXIMUM RATINGS
Symbo l VS VEE VIR VO Tamb Tstg Parameter Power Supply Voltage Power Supply Voltage Input Voltage Range Output Signal Voltage Operating Ambient Temperature Storage Temperature Range T est Cond ition s 15 -15 -15 VIR 7 15 0 to 75 -65 to 150 Unit V V V V o C o C
THERMAL DATA
Symbol Parameter Rth j-amb Thermal Resistance Junction-ambientMax. Pl astic DIP14 Ceramic DIP14 200oC/W 165oC/W SO14 165oC/W
ELECTRICAL CHARACTERISTICS VS= 9 10%V, VE E= -9 10%V ,Tamb= 0 to 75oC, unless otherwise specified
Symbo l Parameter Input Current IIL IIH VOH Input Current Output Voltage T est Conditio ns Low Logic StateVIL = 0V High Logic StateV IH = 5V High Logic StateR L = 3k V IL = 0.8V, V S = 9V, VEE = -9V V IL = 0.8V, V S = 13.2V, VEE = -13.2V Low Logic State V IH = 1.9V, VEE = -9V, VS = 9V V IH = 1.9V, VEE = -13.2V, VS = 13.2V Min. Typ . Max. Un it F ig . 1 1.6 mA 1 10 A V 6 9 -6 -9 6 -6 300 7 10.5 V -7 -10.5 mA 10 -10 15 4.5 19 5.5 12 mA -12 20 6 25 7 34 12 -17 -15 -23 -15 -34 -2.5 333 567 4 V S = VEE = 0V ol = 2V V IH = 1.9V Vs = 9V Vs = 9V V IL = 0.8V V IH = 1.9V Vs = 12V Vs = 12V V IL = 0.8V V IH = 1.9V Vs = 15V Vs = 15V V IL = 0.8V V IH = 1.9V Vs = -9V Vs = -9V V IL = 0.8V Vs = -12V V IH = 1.9V Vs = -12V V IL = 0.8V Vs = -15V V IH = 1.9V Vs = -15V V IL = 0.8V V S = 9V VEE = -9V V EE = -12V V S = 12V 3 2 2 3 2 2 1
VOL
Output Voltage
IOS + * IOS * RO Is
-
Positive Output Short-circuit Current Negative Output Short-circuit Current Output Resistance Positive Supply Current (R i = )
mA
5
IEE
Negative Supply Current (R L = )
-13 -18
mA A mA A mA mA mW
5
Pc
Power Consumption
SWITCHING CHARACTERISTICS VS= 9 1V, VE E= -9 1%V ,Tamb= 25oC
Symb ol Parameter tPHL Propagation Delay Time tTHL tPHL tTHL Fall Time Propagation Delay Time Rise Time Test Co nditions Zi = 3k and 15pF Zi = 3k and 15pF Zi = 3k and 15pF Zi = 3k and 15pF Min. T yp. Max. Unit F ig. 275 350 ns 6 45 110 55 75 175 100 ns ns ns 6 6 6
* Maximum package power dissipation may be exceeded if all outputs are shorted simultaneously.
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TEST CIRCUITS Figure 1 : Input Current Figure 2 : Output Voltage
Figure 3 : Output Short-Circuit Current
Figure 4 : Output Resistance (power off)
Figure 5 : Power Supply Currents
Figure 6 : Switching Response
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Figure 7 : Transfer Characteristics versus Figure 8 : Short-Circuit Output Current versus Temperature
Figure 9 : Output Slew-Rate Load Capacitance
Figure 10 : Output Voltage and Current Limiting Characteristics
Figure 11 : Maximum Operating Temperature versus Power Supply Voltage
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TYPICAL APPLICATION : RS232C Data Transmission
APPLICATION INFORMATION The Electronic Industries Association (EIA) has released the RS232C specification detailing the requirements for the interface between data processing equipment. This standard specifies not only the number and type of interface leads, but also the voltage levels to be used. The MC1488 quad driver and its companion circuit, the MC1489 quad receiver, provide a complete interface system between DTL or TTL logic levels and the RS232C defined levels. The RS232C requirements as applied to drivers are discussed herein. The required driver voltages are defined as between 5 and 15 V in magnitude and are positive for a logic "0" and negative for a logic "1". These voltages are so defined when the drivers are terminated with a 3000 to 7000 resistor. The MC1488 meets this voltage requirement by converting a DTL/TTL logic level into RS232C levels with one stage of inversion. The RS232C specification further requires that during transitions, the driver output slew rate must not exceed 30 V per s. The inherent slew rate of the MC1488 is much too fast for this requirement. The current limited output of the device can be used to control this slew rate by connecting a capacitor to each driver output. The required capacitor can be easily determined by using the relationship C = IOS x T/ V from which Figure 12 is derived. Accordingly, a 330 pF capacitor on each output will guarantee a worst case slew rate of 30 V per s. The interface driver is also required to withstand an accidental short to any other conductor in an interconnecting cable. The worst possible signal on any conductor would be another driver using a plus or minus 15 V, 500 mA source. The MC1488 is designed to indefinitely withstand such a short to all four outputs in a package as long as the power-supply voltages are greater than 9.0 V (i.e., VS 9.0 V ; VEE - 9.0 V). In some power-supply designs, a loss of system power causes a low impedance on the power-supply outputs. When this occurs, a low impedance to ground would exist at the power inputs to the MC1488 effectively shorting the 300 output resistor to ground. If all four outputs were then shorted to plus or minus 15 V, the power dissipation in these resistors would be excessive. Therefore, if the system is designed to permit low impedances to ground at the power-suppies of the drivers, a diode should be placed in each power-supply lead to prevent over-heating in this fault condition. These two diodes, as shown in Figure 13, could be used to decouple all the driver packages in a system. (These same diodes will allow the MC1488 to withstand momentary shorts to the 15 V limits specified in the earlier
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Standard RS232B). The addition of the diodes also permits the MC1488 to withstand faults with power-supplies of less than the 9.0 V stated above. The maximum short-circuit current allowable under fault conditions is more than guaranteed by the previously mentioned 10 mA output current limiting. The MC1488 is an extremely versatile line driver with a miriad of possible applications. Several features of the drivers enhance this versatility : 1. Output Current Limiting - this enables the circuit designer to define the ouptut voltage levels independent of power-supplies and can be accomplished by diode clamping of the output pins. 2. Power-Supply Range - as can be seen from the schematic drawing of the drivers, the positive Figure 12 : Slew Rate versus Capacitance for Isc = 10mA and negative driving elements of the device are essentially independent and do not require matching power-supplies. In fact, the positive supply can very from a minimum seven volts (required for driving the negative pulldown section) to the maximum specified 15 V. The negative supply can vary from approximately 2.5 V to the minimum specified - 15 V. The MC1488 will drive the ouptut to within 2 V of the positive or negative supplies as long as the current output limits are not exceeded. The combination of the current-limiting and supply-voltage features allow a wide combination of possible outputs within the same quad package.
Figure 13 : Power Supply Protection to Meet Power-off Fault Conditions
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Plastic DIP-14 MECHANICAL DATA
mm MIN. a1 B b b1 D E e e3 F I L Z 1.27 3.3 2.54 0.050 8.5 2.54 15.24 7.1 5.1 0.130 0.100 0.51 1.39 0.5 0.25 20 0.335 0.100 0.600 0.280 0.201 1.65 TYP. MAX. MIN. 0.020 0.055 0.020 0.010 0.787 0.065 inch TYP. MAX.
DIM.
P001A
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SO-14 MECHANICAL DATA
DIM. MIN. A a1 a2 b b1 C c1 D E e e3 F G L M S 3.8 4.6 0.5 8.55 5.8 1.27 7.62 4.0 5.3 1.27 0.68 8 (max.) 0.149 0.181 0.019 8.75 6.2 0.35 0.19 0.5 45 (typ.) 0.336 0.228 0.050 0.300 0.157 0.208 0.050 0.026 0.344 0.244 0.1 mm TYP. MAX. 1.75 0.2 1.65 0.46 0.25 0.013 0.007 0.019 0.003 MIN. inch TYP. MAX. 0.068 0.007 0.064 0.018 0.010
P013G
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Information furnished is believed to be accurate and reliable. However, STMicroelectronic s assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of STMicroelectronics. Specification mentioned in this publication are subject to change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not authorized for use as critical components in life support devices or systems withoutexpress written approval of STMicroelectronics. The ST logo is a registered trademark of STMicroelectronics (c) 2000 STMicroelectronics - Printed in Italy - All Rights Reserved STMicroelectronics GROUP OF COMPANIES Australia - Brazil - China - Finland - France - Germany - Hong Kong - India - Italy - Japan - Malaysia - Malta - Morocco Singapore - Spain - Sweden - Switzerland - United Kingdom - U.S.A. http://www.st.com .
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