74AC157 74ACT157 Quad 2-Input Multiplexer November 1988 Revised November 1999 74AC157 74ACT157 Quad 2-Input Multiplexer General Description Features The AC/ACT157 is a high-speed quad 2-input multiplexer. I and I reduced by 50% CC OZ Four bits of data from two sources can be selected using Outputs source/sink 24 mA the common Select and Enable inputs. The four outputs ACT157 has TTL-compatible inputs present the selected data in the true (noninverted) form. The AC/ACT157 can also be used as a function generator. Ordering Code: Order Number Package Number Package Description 74AC157SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Body 74AC157SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide 74AC157MTC MTC16 16 -Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide 74AC157PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide 74ACT157SC M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Body 74ACT157SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide 74ACT157MTC MTC16 16 -Lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153, 4.4mm Wide 74ACT157PC N16E 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Device also available in Tape and Reel. Specify by appending suffix letter X to the ordering code. Logic Symbols Connection Diagram IEEE/IEC Pin Descriptions Pin Names Description I I Source 0 Data Inputs 0a 0d I I Source 1 Data Inputs 1a 1d E Enable Input S Select Input Z Z Outputs a d FACT is a trademark of Fairchild Semiconductor Corporation. 1999 Fairchild Semiconductor Corporation DS009929 www.fairchildsemi.comFunctional Description Truth Table The AC/ACT157 is a quad 2-input multiplexer. It selects Inputs Outputs four bits of data from two sources under the control of a common Select input (S). The Enable input (E) is active- E SI I Z 0 1 LOW. When E is HIGH, all of the outputs (Z) are forced HX X X L LOW regardless of all other inputs. The AC/ACT157 is the LH X L L logic implementation of a 4-pole, 2-position switch where the position of the switch is determined by the logic levels LH X H H supplied to the Select input. The logic equations for the LL L X L outputs are shown below: LL H X H Z = E (I S + I S) a 1a 0a H = HIGH Voltage Level Z = E (I S + I S) L = LOW Voltage Level b 1b 0b X = Immaterial Z = E (I S + I S) c 1c 0c Z = E (I S + I S) d 1d 0d A common use of the AC/ACT157 is the moving of data from two groups of registers to four common output bus- ses. The particular register from which the data comes is determined by the state of the Select input. A less obvious use is as a function generator. The AC/ACT157 can gener- ate any four of the sixteen different functions of two vari- ables with one variable common. This is useful for implementing gating functions. 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 74AC157 74ACT157