STMICROELECTRONICS MC1488

MC1488

RS232C QUAD LINE DRIVER
■
■
■
■
■
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
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
D
DIP14
(Plastic Package)
SO14
(Plastic Micropackage)
ORDER CODES :
MC1488P (Plastic DIP)
MC1488D (SO14)
PIN CONNECTIONS (top view)
March 2000
LOGIC DIAGRAM
1/9
MC1488
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
VOL
IOS + *
–
IOS *
RO
Is
IEE
Pc
T est Conditio ns
Low Logic StateVIL = 0V
Input Current
High Logic StateV IH = 5V
Output Voltage
High Logic StateR L = 3kΩ
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
Output Voltage
Positive Output Short-circuit
Current
Negative Output Short-circuit
Current
Output Resistance
Positive Supply Current
(R i = ∞)
Negative Supply Current
(R L = ∞)
Power Consumption
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
Min. Typ . Max. Un it F ig .
1
1.6 mA
1
10
µA
1
V
6
9
7
10.5
2
2
-6
-9
-7
-10.5
6
10
12
-6
300
-10
-12
V
mA
2
2
3
mA
3
Ω
4
mA
5
15
4.5
19
5.5
20
6
25
7
34
12
-13
-17
-15
-23
-15
-34
-2.5
mA
µA
mA
µA
mA
mA
333
567
mW
-18
5
SWITCHING CHARACTERISTICS VS= ±9 ±1V, VE E= –9 ±1%V ,Tamb= 25oC
Symb ol
Parameter
tPHL
Propagation Delay Time
Test Co nditions
Zi = 3kΩ and 15pF
tTHL
Fall Time
Zi = 3kΩ and 15pF
45
tPHL
Propagation Delay Time
Zi = 3kΩ and 15pF
110
175
ns
6
tTHL
Rise Time
Zi = 3kΩ and 15pF
55
100
ns
6
* Maximum package power dissipation may be exceeded if all outputs are shorted simultaneously.
2/9
Min. T yp. Max. Unit F ig.
275 350
ns
6
75
ns
6
MC1488
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
3/9
MC1488
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
4/9
MC1488
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 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 30 V 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 12 is derived. Accordingly, a 330 pF
capacitor on each output will guarantee a worst
case slew rate of 30 V 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 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 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
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
5/9
MC1488
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
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 12 : Slew Rate versus Capacitance for
Isc = 10mA
Figure 13 : Power Supply Protection to Meet
Power-off Fault Conditions
6/9
MC1488
Plastic DIP-14 MECHANICAL DATA
mm
DIM.
MIN.
a1
0.51
B
1.39
TYP.
inch
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
7/9
MC1488
SO-14 MECHANICAL DATA
mm
DIM.
MIN.
TYP.
A
a1
inch
MAX.
MIN.
TYP.
1.75
0.1
0.068
0.2
a2
MAX.
0.003
0.007
1.65
0.064
b
0.35
0.46
0.013
0.018
b1
0.19
0.25
0.007
0.010
C
0.5
0.019
c1
45 (typ.)
D
8.55
8.75
0.336
0.344
E
5.8
6.2
0.228
0.244
e
1.27
e3
0.050
7.62
0.300
F
3.8
4.0
0.149
0.157
G
4.6
5.3
0.181
0.208
L
0.5
1.27
0.019
0.050
M
S
0.68
0.026
8 (max.)
P013G
8/9
MC1488
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
 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
.
9/9