74HC85D,653

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>₈, Qₐ₌₈ and Qₐ<₈). The 4-bit inputs are weighted (A0 to A3 and B0 to B3), where A3 and B3 are the most significant bits. For proper compare operation the expander inputs (Iₐ>₈, Iₐ₌₈ and Iₐ<₈) to the least significant position must be connected as follows: Iₐ<₈ = Iₐ>₈ = LOW and Iₐ₌₈ = HIGH. For words greater than 4-bits, units can be cascaded by connecting outputs Qₐ>₈, Qₐ₌₈ and Qₐ<₈ to the corresponding inputs of the significant comparator. Inputs include clamp diodes. This enables the use of current limiting resistors to interface inputs to voltages in excess of VCC.

Applications

• Process controllers
• Servo-motor control

Key features

• 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: ANSI/ESDA/JEDEC JS-001 class 2 exceeds 2000 V
• CDM: ANSI/ESDA/JEDEC JS-002 class C3 exceeds 1000 V
• Specified from -40 °C to +85 °C and from -40 °C to +125 °C