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| DM74S257 3-STATE Quad 1-of-2 Data Selector/Multiplexer August 1986 Revised May 2000 DM74S257 3-STATE Quad 1-of-2 Data Selector/Multiplexer 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 S157, S158, with same pin-outs 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 s Typical power dissipation 4.8 ns 320 mW Ordering Code: Order Number DM74S257N Package Number N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide Connection Diagram Function Table Inputs Output Control H L L L L H = HIGH Level L = LOW Level X = Don't Care Z = High Impedance (OFF) Output A X L H X X B X X X L H Y Z L H L H Select X L L H H (c) 2000 Fairchild Semiconductor Corporation DS006482 www.fairchildsemi.com DM74S257 Logic Diagram www.fairchildsemi.com 2 DM74S257 Absolute Maximum Ratings(Note 1) Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 5.5V 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 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 -6.5 20 70 Nom 5 Max 5.25 Units V V V mA mA C Electrical Characteristics over recommended operating free air temperature (unless otherwise noted) 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 Supply Current with Outputs Disabled Conditions VCC = Min, II = -18 mA VCC = Min, IOH = Max VIL = Max, VIH = Min VCC = Min, IOL = Max VIH = Min, VIL = Max VCC = Max, VI = 5.5V VCC = Max VI = 2.7V VCC = Max, VI = 0.5V VCC = Max, VO = 2.4V VIH = Min, VIL = Max VCC = Max, VO = 0.5V VIH = Min, VIL = Max VCC = Max (Note 3) VCC = Max (Note 4) VCC = Max (Note 4) VCC = Max (Note 4) -40 44 60 64 Select Other Select Other 0.5 1 100 50 -4 -2 50 -50 -100 68 93 99 2.4 3.2 Min Typ (Note 2) Max -1.2 Units V V V mA A mA A A mA mA mA mA 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. 3 www.fairchildsemi.com DM74S257 Switching Characteristics at VCC = 5V and TA = 25C RL = 280 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 to HIGH Level Output (Note 5) Output Disable Time to 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 = 15 pF Min Max 7.5 6.5 15 15 19.5 21 8.5 14 CL = 50 pF Min Max 11 10 16 16 23 24 Units ns ns ns ns ns ns ns ns www.fairchildsemi.com 4 DM74S257 3-STATE Quad 1-of-2 Data Selector/Multiplexer Physical Dimensions inches (millimeters) unless otherwise noted 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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