74LS85 Overview
Key Features
- 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, OA < B and OA = B Outputs are connected respectively to the IA > B, IA < B, and IA = B Inputs of the next most significant comparator, as shown in Figure 1. Refer to Applications section of data sheet for high speed method of comparing large words. The Truth Table on the following page describes the operation of the SN74LS85 under all possible logic conditions. The upper 11 lines describe the normal operation under all conditions that will occur in a single device or in 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
- Easily Expandable
