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| DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers June 1989 Revised November 1999 DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers General Description These Schottky-clamped high-performance multiplexers feature 3-STATE outputs that can interface directly with data lines of bus-organized systems. With all but one of the common outputs disabled (at a high impedance state), the low impedance of the single enabled output will drive the bus line to a HIGH or LOW logic level. To minimize the possibility that two outputs will attempt to take a common bus to opposite logic levels, the output enable circuitry is designed such that the output disable times are shorter than the output enable times. This 3-STATE output feature means that n-bit (paralleled) data selectors with up to 258 sources can be implemented for data buses. It also permits the use of standard TTL registers for data retention throughout the system. Features s 3-STATE versions LS157 and LS158 with same pinouts s Schottky-clamped for significant improvement in A-C performance s Provides bus interface from multiple sources in high-performance systems s Average propagation delay from data input 12 ns s Typical power dissipation: 50 mW Ordering Code: Order Number DM74LS257BM DM74LS257BN 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 Logic Diagram Function Table Inputs Output Control H L L L L H = HIGH Level L = LOW Level Output Y A X L H X X B X X X L H LS257 Z L H L H Select X L L H H X = Don't Care Z = High Impedance (off) (c) 1999 Fairchild Semiconductor Corporation DS006417 www.fairchildsemi.com DM74LS257B 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 tables 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 Parameter Supply Voltage HIGH Level Input Voltage LOW Level Input Voltage HIGH Level Output Current LOW Level Output Current Free Air Operating Temperature 0 Min 4.75 2 0.8 -2.6 24 70 Nom 5 Max 5.25 Units V V V mA mA C DC Electrical Characteristics Symbol VI VOH VOL II IIH IIL IOZH IOZL IOS ICCH ICCL ICCZ Parameter Input Clamp Voltage HIGH Level Output Voltage LOW Level Output Voltage 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 with Outputs HIGH Supply Current with Outputs LOW Conditions VCC = Min, II = -18 mA VIL = Max, VIH = Min 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 4) -20 5.9 9.2 12 Select Other Select Other Select Other 2.4 3.1 0.35 0.25 0.5 0.4 0.2 0.1 40 20 -0.8 -0.4 20 -20 -100 10 16 19 Min Typ (Note 2) Max -1.5 Units V V V mA A mA A A mA mA mA mA Supply Current with Outputs Disabled VCC = Max (Note 4) 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: ICC is measured with all outputs open and all possible inputs grounded, while achieving the stated output conditions. www.fairchildsemi.com 2 DM74LS257B Switching Characteristics VCC = 5V and TA = 25C RL = 667 Symbol tPLH tPHL tPLH tPHL tPZH tPZL tPHZ tPLZ Parameter 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 5) Output Disable Time from LOW Level Output (Note 5) Note 5: CL = 5 pF From (Input) To (Output) Data to Output Data to Output Select to Output Select to Output Output Control to Y Output Control to Y Output Control to Y Output Control to Y CL = 45 pF Min Max 18 18 28 35 15 28 28 25 CL = 150 pF Min Max 27 27 35 42 27 38 Units ns ns ns ns ns ns ns ns 3 www.fairchildsemi.com DM74LS257B Physical Dimensions inches (millimeters) unless otherwise noted 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow Package Number M16A www.fairchildsemi.com 4 DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers 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. 5 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 www.fairchildsemi.com |
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