MC1488 RS-232 quad line driver General features ■ Current limited output ±10mA typ. ■ Power-off source impedance 300Ω min. ■ Simple slew rate control with external capacitor ■ Flexible operating supply range ■ Inputs are TTL and µP compatible DIP 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 N° RS232C. SOP Order codes March 2006 DIP14 SO14 (Tape & reel) MC1488P MC1488D1013TR Rev 4 1/ www.st.com 17 Contents MC1488 Contents 1 Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Pin description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3 Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4 Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 5 Test circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 6 Typical applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 6.1 7 2/17 Application information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 MC1488 Diagram 1 Diagram Figure 1. Logic diagram 3/17 Pin description 2 Pin description Figure 2. Pin connections 4/17 MC1488 MC1488 Maximum ratings 3 Maximum ratings Table 1. Absolute maximum ratings Symbol Parameter Value Unit VS Power supply voltage 15 V VEE Power supply voltage -15 V VIR Input voltage range VIR = -15 to 7 V VO Output signal voltage ±15 V 0 to 75 °C -65 to 150 °C Tamb Operating ambient temperature Tstg Storage temperature range Note: Absolute Maximum Ratings are those values beyond which damage to the device may occur. Functional operation under these condition is not implied. Table 2. Thermal data Symbol R thJA Parameter Thermal resistance junction-ambient Max Plastic DIP14 SO14 Unit 200 165 °C/W 5/17 Electrical characteristics MC1488 4 Electrical characteristics Table 3. Electrical characteristics (VS = 9V ± 10%, VEE = -9V ± 10%, Tamb = 0 to 75°C, unless otherwise specified) Symbol Parameter Test Conditions IIL Input Current Figure 3 Low Logic State V IL = 0 V IIH Input Current Figure 3 High Logic State VIH = 5 V VOH Output Voltage Figure 4 High Logic State R L = 3K,Ω VIL = 0.8 V VOL Output Voltage Figure 4 IOS+(1) IOS-(1) RO IS Min. Typ. Max. Unit 1 1.6 mA 10 µA VS = 9V, VEE = -9V 6 7 VS = 13V, VEE = -13V 9 10.5 VS = -9V, VEE = 9V -6 -7 VEE = -13.2V, VS=13.2V -9 -10.5 Positive Output ShortCircuit Current Figure 5 6 10 12 mA Negative Output ShortCircuit Current Figure 5 -6 -10 -12 mA Output Resistance Figure 6 Positive Supply Current (RI = ∞) Figure 7 Low Logic State VIH = 1.9 V V VS = VEE = 0, VOL = ± 2V V Ω 300 VIH = 1.9 V, VS = 9 V 15 20 VIL = 0.8 V, VS = 9 V 4.5 6 VIH = 1.9 V, VS = 12 V 19 25 VIL = 0.8 V, VS = 12 V 5.5 7 mA VIH = 1.9 V, VS = 15 V 34 VIL = 0.8 V, VS = 15 V 12 VIH = 1.9 V, VS = -9 V -13 VIL = 0.8 V, VS = -9 V IEE PC Negative Supply Current V = 1.9 V, V = -12 V IH S (RL = ∞) VIL = 0.8 V, VS = -12 V Figure 7 Power Consumption mA -15 µA -23 mA -15 µA VIH = 1.9 V, VS = -15 V -34 VIL = 0.8 V, VS = -15 V -2.5 VS = 9 V, VEE = -9 V 333 VS = 12 V, VEE = -12 V 567 1. Maximum package power dissipation may be exceeded if all outputs are shorted simultaneously. 6/17 -18 -17 mA mW MC1488 Table 4. Symbol Electrical characteristics Switching characteristics (VS = 9 ± 1V, VEE = -9 ± 1V, Tamb = 25°C) Parameter Test Conditions Min. Typ. Max. Unit tPHL Propagation Delay Time Figure 8 ZI = 3 KΩ and 15 pF 275 350 ns tTHL Fall Time Figure 7 ZI = 3 KΩ and 15 pF 45 75 ns tPHL Propagation Delay Time Figure 8 ZI = 3 KΩ and 15 pF 110 175 ns tTHL Fall Time Figure 8 ZI = 3 KΩ and 15 pF 55 100 ns 7/17 Test circuit 5 8/17 MC1488 Test circuit Figure 3. Input current Figure 4. Output voltage Figure 5. Output short-circuit current MC1488 Test circuit Figure 6. Output resistance (power off) Figure 7. Power supply currents Figure 8. Switching response 9/17 Test circuit MC1488 Figure 9. Transfer characteristics vs input voltage Figure 10. Short-circuit output current vs temperature Figure 11. Output slew-rate load capacitance Figure 12. Output voltage and current limiting characteristics Figure 13. Maximum operating temperature vs power supply voltage 10/17 MC1488 6 Typical applications Typical applications Figure 14. RS232C Data transmission 6.1 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 15V 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 7000Ω 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 30V per µs. 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 15. is derived. Accordingly, a 330 pF capacitor on each output will guarantee a worst case slew rate of 30V per µs. 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 15V, 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 9.0V (i.e., VS ≥ 9.0V; V EE ≤ 9.0V). 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 300W output resistor to ground. If all four outputs were then shorted to plus or minus 15V, the power dissipation in these resistors would be excessive. Therefore, if the system is designed to permit low impedances to ground at the power-supplies of the drivers, a diode should be placed in each power-supply lead to prevent over-heating in this fault condition. 11/17 Typical applications MC1488 These two diodes, as shown in Figure 13, could be used to decoupled all the driver packages in a system. (These same diodes will allow the MC1488 to withstand momentary shorts to the ±15V limits specified in the earlier Standard RS232B). The addition of the diodes also permits the MC1488 to withstand faults with power-supplies of less than the 9.0V 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 mired of possible applications. Several features of the drivers enhance this versatility: 1. Output Current Limiting - this enables the circuit designer to define the output 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 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 15V. The negative supply can vary from approximately -2.5V to the minimum specified 15V. The MC1488 will drive the output to within 2V 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 15. Slew-rate load vs capacitance for ISC = 10mA Figure 16. Power supply protection to meet Power-off fault conditions 12/17 MC1488 Typical applications Plastic DIP-14 MECHANICAL DATA mm. inch DIM. MIN. a1 0.51 B 1.39 TYP MAX. MIN. TYP. MAX. 0.020 1.65 0.055 0.065 b 0.5 0.020 b1 0.25 0.010 D 20 0.787 E 8.5 0.335 e 2.54 0.100 e3 15.24 0.600 F 7.1 0.280 I 5.1 0.201 L Z 3.3 1.27 0.130 2.54 0.050 0.100 P001A 13/17 Typical applications MC1488 SO-14 MECHANICAL DATA DIM. mm. MIN. TYP inch MAX. MIN. TYP. MAX. A 1.35 1.75 0.053 0.069 A1 0.1 0.25 0.004 0.010 A2 1.10 1.65 0.043 0.065 B 0.33 0.51 0.013 0.020 C 0.19 0.25 0.007 0.010 D 8.55 8.75 0.337 0.344 E 3.8 4.0 0.150 0.157 e 1.27 0.050 H 5.8 6.2 0.228 0.244 h 0.25 0.50 0.010 0.020 L 0.4 1.27 0.016 0.050 k 0° 8° 0° 8° ddd 0.100 0.004 0016019D 14/17 MC1488 Typical applications Tape & Reel SO-14 MECHANICAL DATA mm. inch DIM. MIN. A TYP MAX. MIN. 330 MAX. 12.992 C 12.8 D 20.2 0.795 N 60 2.362 T 13.2 TYP. 0.504 22.4 0.519 0.882 Ao 6.4 6.6 0.252 0.260 Bo 9 9.2 0.354 0.362 Ko 2.1 2.3 0.082 0.090 Po 3.9 4.1 0.153 0.161 P 7.9 8.1 0.311 0.319 15/17 Revision history MC1488 7 Revision history Table 5. Revision history Date Revision 17-Mar-2006 4 16/17 Changes Order codes has been updated and new template. MC1488 Please Read Carefully: Information in this document is provided solely in connection with ST products. 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