MC1488
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 15 V. The negative supply can vary from
approximately -2.5 V to the minimum specified - 15 V. The MC1488 will drive the output 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 Load VS Capacitance for
I
SC
= 10 mA
Figure 13 :
Power Supply Protection to Meet Power-off Fault Conditions
8/12
MOTOROLA [ MOTOROLA, INC ]
