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 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.