Revised February 2000 DM74ALS138 3 to 8 Line Decoder/Demultiplexer General Description Features These Schottky-clamped circuits are designed to be used in high-performance memory-decoding or data-routing applications, requiring very short propagation delay times. In high-performance memory systems these decoders can be used to minimize the effects of system decoding. When used with high-speed memories, the delay times of these decoders are usually less than the typical access time of the memory. This means that the effective system delay introduced by the decoder is negligible. ■ Designed specifically for high speed: The DM74ALS138 decodes one-of-eight lines, based upon the conditions at the three binary select inputs and the three enable inputs. Two active-LOW and one active-HIGH enable inputs reduce the need for external gates or inverters when expanding. A 24-line decoder can be implemented with no external inverters, and 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications. ■ Advanced oxide-isolated, ion-implanted Schottky TTL process Memory decoders Data transmission systems ■ 3- to 8-line decoder incorporates 3 enable inputs to simplify cascading and/or data reception ■ Low power dissipation…23 mW typ ■ Switching specifications guaranteed over full temperature and VCC range This decoder/demultiplexer features fully buffered inputs, presenting only one normalized load to its driving circuit. All inputs are clamped with high-performance Schottky diodes to suppress line-ringing and simplify system design. Ordering Code: Order Number Package Number Package Description DM74ALS138M M16A 16-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150 Narrow DM74ALS138SJ M16D 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide DM74ALS138N 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 Function Table Enable Select Inputs Inputs G1 C G2 (Note 1) Outputs B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 X H X X X H H H H H H H L X X X X H H H H H H H H H H L L L L L H H H H H H H H L L L H H L H H H H H H H L L H L H H L H H H H H H L L H H H H H L H H H H H L H L L H H H H L H H H H L H L H H H H H H L H H H L H H L H H H H H H L H H L H H H H H H H H H H L Note 1: G2 = G2A + G2B © 2000 Fairchild Semiconductor Corporation DS006111 www.fairchildsemi.com DM74ALS138 3 to 8 Line Decoder/Demultiplexer September 1986 DM74ALS138 Logic Diagram www.fairchildsemi.com 2 Supply Voltage 7V Input Voltage 7V 0°C to +70°C Operating Free Air Temperature Range Note 2: 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 Storage Temperature Range Typical θJA N Package 75.5°C/W M Package 104.0°C/W Recommended Operating Conditions Symbol Parameter Min Nom Max Units 4.5 5 5.5 V LOW Level Input Voltage 0.8 V VCC Supply Voltage VIH HIGH Level Input Voltage VIL 2 V IOH HIGH Level Output Current −0.4 mA IOL LOW Level Output Current 8 mA TA Free Air Operating Temperature 70 °C 0 Electrical Characteristics over recommended operating free air temperature range. All typical values are measured at VCC = 5V, TA = 25°C. Symbol Parameter Conditions VIK Input Clamp Voltage VCC = 4.5V, II = −18 mA VOH HIGH Level IOH = −0.4 mA Output Voltage VCC = 4.5V to 5.5V VOL LOW Level II Input Current @ Max. Output Voltage Min Typ Max −1.5 VCC − 2 VCC = 4.5V IOL = 8 mA Units V V 0.35 0.5 V mA VCC = 5.5V, VIH = 7V 0.1 IIH HIGH Level Input Current VCC = 5.5V, VIH = 2.7V 20 µA IIL LOW Level Input Current VCC = 5.5V, VIL = 0.4V −0.1 mA IO Output Drive Current VCC = 5.5V ICC Supply Current VCC = 5.5V Input Voltage VO = 2.25V −30 −112 mA 10 mA 5 Switching Characteristics over recommended operating free air temperature range. Symbol tPLH Parameter Conditions Propagation Delay Time VCC = 4.5V to 5.5V From (Input) To (Output) A, B, C LOW-to-HIGH Level Output RL = 500Ω to Y tPHL Propagation Delay Time CL = 50 pF A, B, C tPLH Propagation Delay Time HIGH-to-LOW Level Output to Y Enable LOW-to-HIGH Level Output tPHL to Y Propagation Delay Time Enable HIGH-to-LOW Level Output to Y 3 Min Units Max 6 22 ns 6 18 ns 4 17 ns 5 17 ns www.fairchildsemi.com DM74ALS138 Absolute Maximum Ratings(Note 2) DM74ALS138 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 DM74ALS138 Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 16-Lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm Wide Package Number M16D 5 www.fairchildsemi.com DM74ALS138 3 to 8 Line Decoder/Demultiplexer 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 www.fairchildsemi.com 6