74LS85 is a 4-bit Magnitude Camparator that compares two 4-bit words (A, B), each word having four Parallel Inputs (A0–A3, B0–B3); A3, B3 being the most significant inputs. Operation is not restricted to binary codes, the device will work with any monotonic code. Three Outputs are provided: “A greater than B” (OA>B), “A less than B” (OA<B), “A equal to B” (OA=B). Three Expander Inputs, IA>B, IA<B, IA=B, allow cascading without external gates. For proper compare operation, the Expander Inputs to the least significant position must be connected as follows: IA<B= IA>B = L, IA=B = H. For serial (ripple) expansion, the OA>B, OAB, IA<B, and IA=B Inputs of the next most significant comparator, as shown in Figure 1. Refer to the Applications section of the datasheet for the high-speed method of comparing large words. The Truth Table on the following page describes the operation of the SN54/74LS85 under all possible logic conditions. The upper 11 lines describe the normal operation under all conditions that will occur in a single device or a series expansion scheme. The lower five lines describe the operation under abnormal conditions on the cascading inputs. These conditions occur when the parallel expansion technique is used.

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Package Includes :

1 x 7485 (74LS85) 4 Bit Magnitude Comparator IC