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74HC157 数据表(PDF) 2 Page - NXP Semiconductors |
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74HC157 数据表(HTML) 2 Page - NXP Semiconductors |
2 / 7 page December 1990 2 Philips Semiconductors Product specification Quad 2-input multiplexer 74HC/HCT157 FEATURES • Non-inverting data path • Output capability: standard • ICC category: MSI GENERAL DESCRIPTION The 74HC/HCT157 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A. The 74HC/HCT157 are quad 2-input multiplexers which select 4 bits of data from two sources under the control of a common data select input (S). The four outputs present the selected data in the true (non-inverted) form. The enable input (E) is active LOW. When E is HIGH, all of the outputs (1Y to 4Y) are forced LOW regardless of all other input conditions. Moving the data from two groups of registers to four common output buses is a common use of the “157”. The state of the common data select input (S) determines the particular register from which the data comes. It can also be used as function generator. The device is useful for implementing highly irregular logic by generating any four of the 16 different functions of two variables with one variable common. The “157” is the logic implementation of a 4-pole, 2-position switch, where the position of the switch is determined by the logic levels applied to S. The logic equations are: 1Y = E.(1l1.S + 1l0.S) 2Y = E.(2l1.S + 2l0.S) 3Y = E.(3l1.S + 3l0.S) 4Y = E.(4l1.S + 4l0.S) The “157” is identical to the “158” but has non-inverting (true) outputs. QUICK REFERENCE DATA GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns Notes 1. CPD is used to determine the dynamic power dissipation (PD in µW): PD = CPD × VCC2 × fi + ∑ (CL × VCC2 × fo) where: fi = input frequency in MHz fo = output frequency in MHz ∑ (CL × VCC2 × fo) = sum of outputs CL = output load capacitance in pF VCC = supply voltage in V 2. For HC the condition is VI = GND to VCC For HCT the condition is VI = GND to VCC − 1.5 V ORDERING INFORMATION See “74HC/HCT/HCU/HCMOS Logic Package Information”. SYMBOL PARAMETER CONDITIONS TYPICAL UNIT HC HCT tPHL/ tPLH propagation delay CL = 15 pF; VCC = 5 V nI0, nI1 to nY 11 13 ns E to nY 11 12 ns S to nY 12 19 ns CI input capacitance 3.5 3.5 pF CPD power dissipation capacitance per multiplexer notes 1 and 2 70 70 pF |
类似零件编号 - 74HC157 |
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类似说明 - 74HC157 |
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