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| DM74LS251 3-STATE 1-of-8 Line Data Selector/Multiplexer August 1986 Revised March 2000 DM74LS251 3-STATE 1-of-8 Line Data Selector/Multiplexer General Description These data selectors/multiplexers contain full on-chip binary decoding to select one-of-eight data sources, and feature a strobe-controlled 3-STATE output. The strobe must be at a low logic level to enable these devices. The 3STATE outputs permit direct connection to a common bus. When the strobe input is HIGH, both outputs are in a highimpedance state in which both the upper and lower transistors of each totem-pole output are OFF, and the output neither drives nor loads the bus significantly. When the strobe is LOW, the outputs are activated and operate as standard TTL totem-pole outputs. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output control circuitry is designed so that the average output disable time is shorter than the average output enable time. Features s 3-STATE version of DM74LS151 s Interface directly with system bus s Perform parallel-to-serial conversion s Permit multiplexing from N-lines to one line s Complementary outputs provide true and inverted data s Maximum number of common outputs: 129 s Typical propagation delay time (D to Y): 17 ns s Typical power dissipation: 35 mW Ordering Code: Order Number DM74LS251M DM74LS251N Package Number M16A N16E Package Description 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow 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. Connection Diagram Function Table Inputs Select C X L L L L H H H H B X L L H H L L H H A X L H L H L H L H Strobe S H L L L L L L L L Outputs Y Z D0 D1 D2 D3 D4 D5 D6 D7 W Z D0 D1 D2 D3 D4 D5 D6 D7 H = HIGH Logic Level L = LOW Logic Level X = Don't Care Z = High Impedance (OFF) D0, D1...D7 = The level of the respective D input (c) 2000 Fairchild Semiconductor Corporation DS006415 www.fairchildsemi.com DM74LS251 Logic Diagram www.fairchildsemi.com 2 DM74LS251 Absolute Maximum Ratings(Note 1) Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 7V 0C to +70C -65C to +150C Note 1: The "Absolute Maximum Ratings" are those values beyond which the safety of the device cannot be guaranteed. The device should not be operated at these limits. The parametric values defined in the "Electrical Characteristics" table are not guaranteed at the absolute maximum ratings. The "Recommended Operating Conditions" table will define the conditions for actual device operation. Recommended Operating Conditions Symbol VCC VIH VIL IOH IOL TA Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature 0 Parameter Min 4.75 2 0.8 -2.6 24 70 Nom 5 Max 5.25 Units V V V mA mA C Electrical Characteristics over recommended operating free air temperature range (unless otherwise noted) Symbol VI VOH VOL Parameter Input Clamp Voltage HIGH Level Output Voltage LOW Level Output Voltage II IIH IIL IOZH IOZL IOS ICC1 ICC2 Input Current @ Max Input Voltage HIGH Level Input Current LOW Level Input Current Off-State Output Current with HIGH Level Output Voltage Applied Off-State Output Current with LOW Level Output Voltage Applied Short Circuit Output Current Supply Current Supply Current Conditions VCC = Min, II = -18 mA VCC = Min, IOH = Max VIL = Max, VIH = Min VCC = Min, IOL = Max VIL = Max, VIH = Min IOL = 12 mA, VCC = Min VCC = Max, VI = 7V VCC = Max, VI = 2.7V VCC = Max, VI = 0.4V VCC = Max, VO = 2.7V VIH = Min, VIL = Max VCC = Max, VO = 0.4V VIH = Min, VIL = Max VCC = Max (Note 3) VCC = Max (Note 4) VCC = Max (Note 5) -20 6.1 7.1 2.4 3.1 0.35 0.25 0.5 0.4 0.1 20 -0.4 20 -20 -100 10 12 mA A mA A A mA mA mA Min Typ (Note 2) Max -1.5 Units V V V Note 2: All typicals are at VCC = 5V, TA = 25C. Note 3: Not more than one output should be shorted at a time, and the duration should not exceed one second. Note 4: ICC1 is measured with the outputs open, STROBE grounded, and all other inputs at 4.5V. Note 5: ICC2 is measured with the outputs open and all inputs at 4.5V. 3 www.fairchildsemi.com DM74LS251 Switching Characteristics at VCC = 5V and TA = 25C From (Input) Symbol Parameter to (Output) A, B, C (4 Levels) to Y A, B, C (4 Levels) to Y A, B, C (3 Levels) to W A, B, C (3 Levels) to W D to Y D to Y D to W D to W Strobe to Y Strobe to Y Strobe to Y Strobe to Y Strobe to W Strobe to W Strobe to W Strobe to W CL = 45 pF Min tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL tPZH tPZL tPHZ tPLZ tPZH tPZL tPHZ tPLZ Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output Output Enable Time to HIGH Level Output Output Enable Time to LOW Level Output Output Disable Time from HIGH Level Output (Note 6) Output Disable Time from LOW Level Output (Note 6) Output Enable Time to HIGH Level Output Output Enable Time to LOW Level Output Output Disable Time from HIGH Level Output (Note 6) Output Disable Time from LOW Level Output (Note 6) Note 6: CL = 5 pF RL = 667 CL = 150 pF Min Max 53 53 38 42 35 38 25 25 60 51 ns ns ns ns ns ns ns ns ns ns ns ns 40 47 ns ns ns ns Units Max 45 45 33 33 28 28 15 15 45 40 45 25 27 40 55 25 www.fairchildsemi.com 4 DM74LS251 Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Package Number M16A 5 www.fairchildsemi.com DM74LS251 3-STATE 1-of-8 Line Data Selector/Multiplexer Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Package Number N16E Fairchild does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and Fairchild reserves the right at any time without notice to change said circuitry and specifications. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. www.fairchildsemi.com 6 2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com |
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