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 ■ 3-STATE versions LS157 and LS158 with same pinouts ■ Schottky-clamped for significant improvement in A-C performance ■ Provides bus interface from multiple sources in high-performance systems ■ Average propagation delay from data input 12 ns ■ Typical power dissipation: 50 mW Ordering Code: Order Number Package Number Package Description DM74LS257BM M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow DM74LS257BN N16E 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 Output Y Select A B LS257 H X L L X X Z L X L L L H X H L H X L L L H X H H Control H = HIGH Level L = LOW Level X = Don’t Care Z = High Impedance (off) © 1999 Fairchild Semiconductor Corporation DS006417 www.fairchildsemi.com DM74LS257B 3-STATE Quad 2-Data Selectors/Multiplexers June 1989 DM74LS257B Absolute Maximum Ratings(Note 1) Supply Voltage 7V Input Voltage 7V 0°C to +70°C Operating Free Air Temperature Range Storage Temperature Range 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. −65°C to +150°C Recommended Operating Conditions Symbol Parameter Min Nom Max Units VCC Supply Voltage 4.75 5 5.25 V VIH HIGH Level Input Voltage VIL LOW Level Input Voltage 0.8 V IOH HIGH Level Output Current −2.6 mA IOL LOW Level Output Current 24 mA TA Free Air Operating Temperature 70 °C 2 V 0 DC Electrical Characteristics Symbol Parameter Conditions VI Input Clamp Voltage VCC = Min, II = −18 mA VOH HIGH Level Output Voltage VIL = Max, VIH = Min VOL II IIH IIL IOZH IOZL Min Typ (Note 2) Max −1.5 2.4 3.1 LOW Level Output VIL = Max, VIH = Min 0.35 0.5 IOL = 12 mA, VCC = Min 0.25 0.4 Input Current @ Max VCC = Max, Select 0.2 Input Voltage VI = 7V Other 0.1 HIGH Level Input VCC = Max, Select 40 Current VI = 2.7V Other 20 LOW Level Input VCC = Max, Select −0.8 Current VI = 0.4V Other −0.4 OFF-State Output Current with VCC = Max, VO = 2.7V HIGH Level Output Voltage Applied VIH = Min, VIL = Max OFF-State Output Current with VCC = Max, VO = 0.4V LOW Level Output Voltage Applied VIH = Min, VIL = Max Short Circuit Output Current VCC = Max (Note 3) ICCH Supply Current with Outputs HIGH VCC = Max (Note 4) ICCL Supply Current with Outputs LOW VCC = Max (Note 4) ICCZ Supply Current with Outputs Disabled VCC = Max (Note 4) 20 mA µA mA µA −20 µA mA 5.9 10 mA 9.2 16 mA 12 19 mA 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. 2 V −100 −20 Note 2: All typicals are at VCC = 5V, TA = 25°C. www.fairchildsemi.com V V Voltage IOS Units VCC = 5V and TA = 25°C RL = 667Ω Symbol Parameter CL = 45 pF From (Input) To (Output) tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPLH Propagation Delay Time LOW-to-HIGH Level Output tPHL Propagation Delay Time HIGH-to-LOW Level Output tPZH Output Enable Time to HIGH Level Output tPZL Output Enable Time to LOW Level Output tPHZ Output Disable Time from HIGH Level Output (Note 5) tPLZ Output Disable Time from LOW Level Output (Note 5) Min CL = 150 pF Max Min Units Max Data to Output 18 27 ns Data to Output 18 27 ns Select to Output 28 35 ns Select to Output 35 42 ns Output Control to Y 15 27 ns Output Control to Y 28 38 ns Output Control to Y 28 ns Output Control to Y 25 ns Note 5: CL = 5 pF 3 www.fairchildsemi.com DM74LS257B Switching Characteristics 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: 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. 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 5 www.fairchildsemi.com