74F157ASC ON Semiconductor

74F157A Quad 2-Input Multiplexer April 1988 Revised September 2000 74F157A Quad 2-Input Multiplexer General Description The F157A is a high-speed quad 2-input multiplexer. Four bits of data from two sources can be selected using the common Select and Enable inputs. The four outputs present the selected data in the true (non-inverted) form. The F157A can also be used to generate any four of the 16 different functions to two variables. Ordering Code: Order Number Package Number Package Description 74F157ASC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 74F157ASJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide 74F157APC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Devices also available in Tape and Reel. Specify by appending the suffix letter X to the ordering code. Logic Symbols Connection Diagram IEEE/IEC 2000 Fairchild Semiconductor Corporation DS009483 www.fairchildsemi.comUnit Loading/Fan Out U.L. Input I /I IH IL Pin Names Description Output I /I HIGH/LOW OH OL I I Source 0 Data Inputs 1.0/1.0 20 A/0.6 mA 0a 0d I I Source 1 Data Inputs 1.0/1.0 20 A/0.6 mA 1a 1d E Enable Input (Active LOW) 1.0/1.0 20 A/0.6 mA S Select Input 1.0/1.0 20 A/0.6 mA Z Z Outputs 50/33.3 1 mA/20 mA a d Truth Table Functional Description The F157A is a quad 2-input multiplexer. It selects four bits Inputs Output of data from two sources under the control of a common Select input (S). The Enable input (E) is active LOW. When I I E S Z 0 1 E is HIGH, all of the outputs (Z) are forced LOW regardless of all other inputs. The F157A is the logic implementation of HX X X L a 4-pole, 2-position switch where the position of the switch LH X L L is determined by the logic levels supplied to the Select input. The logic equations for the outputs are shown below: LH X H H Z = E (I S + I S) n 1n 0n LL L X L A common use of the F157A is the moving of data from two LL H X H groups of registers to four common output busses. The H = HIGH Voltage Level particular register from which the data comes is determined L = LOW Voltage Level by the state of the Select input. A less obvious use is as a X = Immaterial function generator. The F157A can generate any four of the 16 different functions of two variables with one variable common. This is useful for implementing highly irregular logic. Logic Diagram Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays. www.fairchildsemi.com 2 74F157A