MC1488
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7
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 vary from a minimum 7.0 V (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 2.0 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. Thus if only a portion of the
four drivers are used for driving EIA−232D lines, the
remainder could be used for DTL to MOS or even DTL to
DTL translation. Figure 17 shows one such combination.
Figure 16. DTL/TTL−to−MOS Translator
Figure 17. Logic Translator Applications
MOS Output
(with V
SS
= GND)
10 k
1.0 k
DTL
TTL
Input
1/4 MC1488
12 V
-12 V-12 V
MOS Output
-10 V to 0 V
DTL Output
-0.7 V to +5.7 V
HTL Output
-0.7 V to 10 V
RTL Output
-0.7 V to +3.7 V
-12 V
10 k
1.0 k
5.0 V
8
1
11
6
3.0 V
3
MC1488
13
12
10
9
5
4
DTL
MMOS
Input
DTL
HTL
Input
2
DTL
NAND
Gate
Input
DTL
Input
12 V
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