FEATURES
· Serial or parallel expansion without extra gating
· Magnitude comparison of any binary words
· Output capability: standard
· ICC category: MSI

GENERAL DESCRIPTION
The 74HC/HCT85 are high-speed Si-gate CMOS devices
and are pin compatible with low power Schottky TTL
(LSTTL). They are specified in compliance with JEDEC
standard no. 7A.
The 74HC/HCT85 are 4-bit magnitude comparators that
can be expanded to almost any length. They perform
comparison of two 4-bit binary, BCD or other monotonic
codes and present the three possible magnitude results at
the outputs (QA>B, QA=B and QAweighted (A0 to A3 and B0 to B3), where A3 and B3 are the
most significant bits.
The operation of the “85” is described in the function table,
showing all possible logic conditions. The upper part of the
table describes the normal operation under all conditions
that will occur in a single device or in a series expansion
scheme. In the upper part of the table the three outputs are
mutually exclusive. In the lower part of the table, the
outputs reflect the feed forward conditions that exist in the
parallel expansion scheme.
For proper compare operation the expander inputs (IA>B,
IA=B and IAconnected as follows: IAB = = LOW and
IA=B = HIGH.
For words greater than 4-bits, units can be cascaded by
connecting outputs QAB and QA=B to the
corresponding inputs of the significant comparator.