General description
The HEF4585B is a 4-bit magnitude comparator that compares two 4-bit words, A and B, and determines whether A is greater than B, A is equal to B, or A is less than B. Each word has four parallel inputs (A0 to A3 and B0 to B3) with A3 and B3 being the most significant inputs. Three outputs are provided: A greater than B (QA>B), A less than B (QA<B) and A equal to B (QA=B). Three expander inputs (IA>B, IA<B, and IA=B) allow cascading of the devices, to compare 8, 12, 16, ..., bits without external gates.
To operate a single device or a device in the least significant position in a cascaded chain, the expander inputs are connected as follows: IA=B = IA>B = HIGH and IA<B = LOW. All other cascaded devices have IA=B and IA<B connected to QA=B and QA<B respectively of the previous (less significant) device in the chain, while input IA>B is connected to a HIGH (see Figure 6). Operation is not restricted to pure binary code; the devices will work with any monotonic code. Table 3 describes the operation of the device under all possible logic conditions.
It operates over a recommended VDD power supply range of 3 V to 15 V referenced to VSS (usually ground). Unused inputs must be connected to VDD, VSS, or another input.

FEATUREs and benefits
■ Fully static operation
■ 5 V, 10 V, and 15 V parametric ratings
■ Standardized symmetrical output characteristics
■ Specified from −40 °C to +85 °C
■ Complies with JEDEC standard JESD 13-B