Electronic Terms for Engineers
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

IC Magnitude Comparator Chips

The graphic shows one example of a Magnitude Comparator. The same function could also be represented using different logic gates.

8-input Magnitude Comparator IC, logic diagram view
8-input Magnitude Comparator Circuit

Magnitude Comparator. This Magnitude Comparator can be used perform comparisons of two 8-bit binary or BCD words. The output provides both a P equals Q function or P greater than Q function.

A Magnitude Comparator would be considered standard logic or glue logic when a discrete IC is used. However, because of the internal complexity, a Magnitude Comparator would also be considered an MSI Function [Medium Scale Integration].
A similar function is the Identity Comparator.

Magnitude Comparator by Function:
Note in most cases when a 54xx device is listed, a 74xx device is also available.
74xx represents the commercial temperature range and 54xx represents the military variant, or industrial temperature range [IC Prefixes]. In either case the component grade that seemed to still be in production is listed.

54LS85 4-Bit Magnitude Comparators

74ALS518 8-Bit Identity Comparators (P=Q) w/ Enable, Open Collector Outputs, 20K Ohm Q-Input Pullup Resistor

54ALS520 8-Bit Identity/Magnitude Comparators (P=Q) with Enable and 20K Ohm Q-Input Pullup Resistors

74F521 8-Bit Identity/Magnitude Comparators (P=Q) with Enable

54LS682 8-Bit Identity/Magnitude Comparators

54LS684 8-Bit Identity/Magnitude Comparators

54ALS688 8-Bit Identity/Magnitude Comparators (P=Q) with Enable

54AS885 8-Bit Magnitude Comparators

54HCT85 4-Bit Magnitude Comparator

54HC85 4-Bit Magnitude Comparator

54HC688 8-Bit Identity/Magnitude Comparators (P=Q) with Enable

4063 [CMOS] 4-Bit Magnitude Comparators

4585 [CMOS] 4-Bit Magnitude Comparators

Using a Magnitude Comparator in a circuit assumes the designer either has no available programmable IC or no available input pins on the programmable device. Because using such a large IC to perform this simple function is not the best usage of board space.

Editor note; the 4000 series of parts were the common line of completely CMOS parts, with all of their internal gates being CMOS. A second line or generation was developed using the 4500 series of part numbers. However I don't know that the pining remained the same between the two series of parts, or if they reused the same function numbers. That is; could a 4563 part be a direct replacement for a 4063, or even if a 4563 part was ever produced. However the point is a small one, because in general the CMOS families are out-dated, and are only found in a small niche.

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