1. General description
The 74HC85; 74HCT85 is a 4-bit magnitude comparator 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. For proper
compare operation the expander inputs (IA>B, IA=B and IAbe connected as follows: IAB = LOW and IA=B = HIGH. For words greater than 4-bits, units
can be cascaded by connecting outputs QA>B, QA=B and QAthe significant comparator. Inputs include clamp diodes. This enables the use of current limiting
resistors to interface inputs to voltages in excess of VCC.
2. Features and benefits
• Wide supply voltage range from 2.0 to 6.0 V
• CMOS low power dissipation
• High noise immunity
• Latch-up performance exceeds 100 mA per JESD 78 Class II Level B
• Input levels:
• For 74HC85: CMOS level
• For 74HCT85: TTL level
• Complies with JEDEC standards:
• JESD8C (2.7 V to 3.6 V)
• JESD7A (2.0 V to 6.0 V)
• ESD protection:
• HBM JESD22-A114-A exceeds 2000 V
• MM JESD22-A115-A exceeds 200 V
• Specified from -40 °C to +85 °C and from -40 °C to +125 °C
3. Applications
• Process controllers
• Servo-motor control