4000系列逻辑芯片/HEF4585BT
DESCRIPTION
The HEF4585B is a 4-bit magnitude comparator which compares two 4-bit words A and B, whether they are ‘less than’, ‘equal to’, or ‘greater than’. Each word has four parallel inputs A0 to A3 and B0 to B3; A3 and B3 being the most significant inputs. Three outputs are provided; A greater than B OA > B, A less than B OA < B and A equal to B OA = B. Three expander inputs IA > B, IA < B and IA = B allow cascading of the devices without external gates.
For proper compare operation the expander inputs to the least significant position must be connected as follows: IA = B = IA > B = HIGH, IA < B = LOW. For words greater than 4-bits, units can be cascaded by connecting outputs OA < B and OA = B to the corresponding inputs of the next significant comparator input IA > B is connected to a HIGH.
Operation is not restricted to binary codes, the devices will work with any monotonic code. The function table describes the operation of the device under all possible logic conditions.