MC1488
April 1993
RS232C QUAD LINE DRIVER
.CURRENT LIMITED OUTPUT±10mATYP.
.POWER-OFF SOURCE IMPEDANCE
300Ω MIN.
.SIMPLE SLEWRATE CONTROL WITH EX-
TERNALCAPACITOR
.FLEXIBLEOPERATING SUPPLY RANGE
.INPUTS ARE TTL AND µP COMPATIBLE
DESCRIPTION
The MC1488 is a monolithic quad line driver de-
signed to interface data terminal equipment with
data communications equipment in conformance
N
DIP14
(Plastic Package)
ORDER CODES : MC1488P (Plastic DIP)
MC1488L (Ceramic DIP)
MC1488D (SO14)
PIN CONNECTIONS (top view) LOGIC DIAGRAM
D
SO14
(Plastic Micropackage)
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ABSOLUTE MAXIMUM RATINGS
Symbol Parameter Test Conditions Unit
VSPower Supply Voltage 15 V
VEE Power Supply Voltage –15 V
VIR Input VoltageRange –15 ≤VIR ≤7V
V
O
Output Signal Voltage ±15 V
Tamb Operating Ambient Temperature 0 to 75 oC
Tstg Storage Temperature Range –65 to 150 oC
THERMALDATA
Symbol Parameter Plastic DIP14 Ceramic DIP14 SO14
Rth j-amb Thermal Resistance Junction-ambient Max. 200oC/W 165oC/W 165oC/W
ELECTRICAL CHARACTERISTICS
VS=9±10%V, VEE
=–9±10%V ,Tamb=0to75
o
C, unlessotherwisespecified
Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig.
IIL Input Current Low Logic State VIL = 0V 1 1.6 mA 1
IIH Input Current High Logic State VIH =5V 10 µA1
V
OH Output Voltage High Logic State RL=3kΩ
V
IL = 0.8V, VS= 9V, VEE = –9V
VIL = 0.8V, VS= 13.2V, VEE = –13.2V 6
97
10.5
V2
2
VOL Output Voltage Low Logic State
VIH = 1.9V, VEE = –9V, VS=9V
V
IH = 1.9V, VEE = –13.2V, VS= 13.2V -6
-9 -7
-
10.5
V2
2
IOS +* Positive Output Short-circuit
Current 6 10 12 mA 3
IOS –* Negative Output Short-circuit
Current -6 -10 -12 mA 3
ROOutput Resistance VS=V
EE =0 V
ol =±2V 300 Ω4
IsPositive Supply Current
(Ri=∞)VIH = 1.9V Vs=9V
V
IL = 0.8V Vs=9V
V
IH = 1.9V Vs= 12V
VIL = 0.8V Vs= 12V
VIH = 1.9V Vs= 15V
VIL = 0.8V Vs= 15V
15
4.5
19
5.5
20
6
25
7
34
12
mA 5
IEE Negative Supply Current
(RL=∞)VIH = 1.9V Vs= -9V
VIL = 0.8V Vs= -9V
VIH = 1.9V Vs= -12V
VIL = 0.8V Vs= -12V
VIH = 1.9V Vs= -15V
VIL = 0.8V Vs= -15V
-13
-18
-17
-15
-23
-15
-34
-2.5
mA
µA
mA
µA
mA
mA
5
PcPower Consumption VS=9V V
EE = -9V
VS= 12V VEE = -12V 333
567 mW
SWITCHING CHARACTERISTICS
VS=±9±1V,VEE
=–9±1%V ,Tamb=25oC
Symbol Parameter Test Conditions Min. Typ. Max. Unit Fig.
tPHL Propagation Delay Time Zi=3kΩand15pF 275 350 ns 6
tTHL Fall Time Zi=3kΩand15pF 45 75 ns 6
tPHL Propagation Delay Time Zi=3kΩand15pF 110 175 ns 6
tTHL Rise Time Zi=3kΩand15pF 55 100 ns 6
* Maximum package power dissipation may beexceeded if all outputs are shorted simultaneously.
MC1488
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TEST CIRCUITS
Figure 1 : Input Current
Figure 3 : OutputShort-Circuit Current
Figure 5 : PowerSupply Currents
Figure 2 : Output Voltage
Figure 4 : Output Resistance(power off)
Figure 6 : Switching Response
MC1488
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Figure 7 : Transfer Characteristicsversus
PowerSupply Voltage Figure 8 : Short-CircuitOutputCurrent versus
Temperature
Figure 9 : OutputSlew-RateLoad Capacitance Figure 10 : Output Voltage and Current Limiting
Characteristics
Figure 11: Maximum OperatingTemperature
versusPower Supply Voltage
MC1488
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TYPICAL APPLICATION : RS232C Data Transmission
The Electronic Industries Association (EIA) has
released the RS232C specification detailing the
requirementsfor the interfacebetween data proc-
essing equipment.This standardspecifies not only
thenumberandtypeofinterfaceleads,butalsothe
voltagelevels tobe used.The MC1488 quaddriver
and its companion circuit, the MC1489 quad re-
ceiver, provide a complete interface system be-
tween DTL or TTL logic levels and the RS232C
defined levels. The RS232C requirements as ap-
pliedto drivers are discussedherein.
The required driver voltages are defined as be-
tween5 and15 V inmagnitudeandarepositive for
a logic ”0” and negative for a logic ”1”. These
voltagesareso definedwhen thedrivers are termi-
natedwitha 3000to 7000Ωresistor. TheMC1488
meets this voltage requirement by converting a
DTL/TTL logic level into RS232C levels with one
stageof inversion.
TheRS232Cspecificationfurtherrequiresthatdur-
ing transitions, the driver output slewrate must not
exceed 30 V per µs. The inherent slew rate of the
MC1488 is much too fast for this requirement. The
currentlimited output of thedevice can be used to
controlthis slew rate by connectinga capacitorto
each driver output.The required capacitorcan be
easilydeterminedby using the relationshipC = IOS
x∆T/ ∆V from which Figure 12 is derived. Accord-
ingly, a 330 pF capacitor on each output will guar-
antee a worst case slewrate of 30 V per µs.
Theinterfacedriverisalsorequiredtowithstandan
accidentalshort to anyother conductorin an inter-
connectingcable. The worst possiblesignalonany
conductorwould be another driver using a plus or
minus 15 V, 500 mA source. The MC1488 is de-
signed to indefinitely withstand such a short to all
fouroutputsinapackageaslongasthepower-sup-
ply voltages are greater than 9.0 V (i.e., VS ≥9.0
V;V
EE ≤- 9.0 V). In somepower-supply designs,
a loss of system power causes a low impedance
on the power-supply outputs. When this occurs,a
low impedanceto groundwould exist at the power
inputsto theMC1488 effectivelyshortingthe 300Ω
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
impedancestogroundat the power-suppiesof 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 driverpack-
ages in a system. (These same diodes will allow
the MC1488 to withstandmomentary shorts to the
±15 V limits specified in the earlier Standard
RS232B). The addition of the diodes also permits
the MC1488 to withstand faults with power-sup-
pliesof lessthan the 9.0 V stated above.
Themaximumshort-circuitcurrentallowable under
fault conditions is more than guaranteed by the
previouslymentioned10mAoutputcurrentlimiting.
APPLICATION INFORMATION
MC1488
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Figure 12 : Slew Rate versus Capacitancefor
Isc =10mA Figure 13 : PowerSupply Protectionto Meet
Power-off Fault Conditions
The MC1488 is an extremely versatile line driver
with a miriad of possible applications.Severalfea-
tures of the drivers enhance this versatility :
1. OutputCurrent Limiting - this enablesthe circuit
designer to define the ouptut voltage levels inde-
pendent of power-supplies and can be accom-
plishedby diodeclamping of the outputpins.
2. Power-SupplyRange - as can be seen from the
schematicdrawing of the drivers, the positiveand
negativedriving elementsof the device areessen-
tially independent and do not require matching
power-supplies.Infact,thepositivesupplycanvery
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 ouptutto within 2
V ofthepositiveornegativesuppliesas longasthe
currentoutput limits are notexceeded.Thecombi-
nation of the current-limiting and supply-voltage
featuresallow a widecombination of possibleout-
puts withinthe samequad package.
OTHER APPLICATION
MC1488
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DIP14PACKAGE MECHANICAL DATA
DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
a1 0.51 0.020
B 1.39 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 3.3 0.130
Z 1.27 2.54 0.050 0.100
MC1488
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SO14 PACKAGE MECHANICAL DATA
DIM. mm inch
MIN. TYP. MAX. MIN. TYP. MAX.
A 1.75 0.069
a1 0.1 0.25 0.004 0.009
a2 1.6 0.063
b 0.35 0.46 0.014 0.018
b1 0.19 0.25 0.007 0.010
C 0.5 0.020
c1 45 (typ.)
D 8.55 8.75 0.336 0.344
E 5.8 6.2 0.228 0.244
e 1.27 0.050
e3 7.62 0.300
F 3.8 4.0 0.15 0.157
L 0.4 1.27 0.016 0.050
M 0.68 0.027
S 8 (max.)
MC1488
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Information furnished is believed to be accurate and reliable. However, SGS-THOMSON Microelectronics assumes no responsibility
for the consequences of use of such information nor for any infringement of patents or other rights ofthird parties which mayresult
from its use. No license is granted by implicationor otherwise under any patent or patent rights of SGS-THOMSONMicroelectronics.
Specifications mentioned in this publication are subject to change without notice. This publication supersedes and replaces all
information previously supplied.SGS-THOMSON Microelectronics products arenot authorized for use as critical components in life
support devices or systems without express written approvalof SGS-THOMSON Microelectronics.
1994 SGS-THOMSON Microelectronics - All Rights Reserved
SGS-THOMSON MicroelectronicsGROUP OF COMPANIES
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MC1488
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