MC1488D1013TR STMicroelectronics, MC1488D1013TR Datasheet - Page 11

• Manufacturer Part Number: MC1488D1013TR
• Description: IC DRIVER QUAD LINE 14 SOIC
• Manufacturer: STMicroelectronics
• Type: Driverr

Specifications of MC1488D1013TR

• Number Of Drivers/receivers: 4/0
• Protocol: RS232
• Voltage - Supply: 15V
• Mounting Type: Surface Mount
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-1950-2

MC1488
6
6.1
Typical applications
Figure 14. RS232C Data transmission
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 = I
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., V
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.
Application information
S
≥ 9.0V; V
EE
OS
≤ 9.0V). In some power-supply designs, a loss of
x ∆T/∆V from which
Figure 15.
Typical applications
is derived.
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