MM54HC182/MM74HC182
Look-Ahead Carry Generator
General Description
The MM54HC182/MM74HC182 is a high speed LOOKAHEAD
CARRY GENERATOR utilize advanced silicon-gate
CMOS technology. It has the low power consumption and
high noise immunity of standard CMOS integrated circuits,
along with the ability to drive 10 LS-TTL loads.
These circuits are capable of anticipating a carry across four
binary adders or groups of adders. They are cascadable to
perform full look-ahead across n-bit adders. Carry, generate-
carry, and propagate-carry functions are provided as
shown in the pin designation table.
When used in conjunction with the HC181 arithmetic logic
unit, these generators provide high-speed carry look-ahead
capability for any word length. Each HC182 generates the
look-ahead (anticipated carry) across a group of four ALU's
and, in addition, other carry look-ahead circuits may be employed
to anticipate carry across sections of four lookahead
packages up to n-bits. The method of cascading circuits
to perform multi-level look-ahead is illustrated under
typical application data.
Carry input and output of the ALU's are in their true form,
and the carry propagate (P) and carry generate (G) are in
negated form; therefore, the carry functions (inputs, outputs,
generate, and propagate) of the look-ahead generators are
implemented in the compatible forms for direct connection
to the ALU. Reinterpretations of carry functions as explained
on the HC181 data sheet are also applicable to and
compatible with the look-ahead generator.