The ’HC85 and ’HCT85 are high speed magnitude comparators that use silicon-gate CMOS technology to achieve operating speeds similar to LSTTL with the low power consumption of standard CMOS integrated circuits.
These 4-bit devices compare two binary, BCD, or other monotonic codes and present the three possible magnitude results at the outputs (A > B, A < B, and A = B). The 4-bit input words are weighted (A0 to A3 and B0 to B3), where A3 and B3 are the most significant bits.
The devices are expandable without external gating, in both serial and parallel fashion. The upper part of the truth table indicates operation using a single device or devices in a serially expanded application. The parallel expansion scheme is described by the last three entries in the truth table.
- Buffered Inputs and Outputs
- Typical Propagation Delay: 13ns (Data to Output at VCC = 5V, CL = 15pF, TA = 25°C
- Serial or Parallel Expansion Without External Gating
- Fanout (Over Temperature Range)
- Standard Outputs . . . . . . . 10 LSTTL Loads
- Bus Driver Outputs . . . . . 15 LSTTL Loads
- Wide Operating Temperature Range . . . –55°C to 125°C
- Balanced Propagation Delay and Transition Times
- Significant Power Reduction Compared to LSTTL Logic ICs
- HC Types
- 2V to 6V Operation
- High Noise Immunity: NIL = 30%, NIH = 30%of VCC at VCC = 5V
- HCT Types
- 4.5V to 5.5V Operation
- Direct LSTTL Input Logic Compatibility, VIL = 0.8V (Max), VIH = 2V (Min)
- CMOS Input Compatibility, Il 1µA at VOL, VOH