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| DM74S138 * DM74S139 Decoder/Demultiplexer August 1986 Revised April 2000 DM74S138 * DM74S139 Decoder/Demultiplexer General Description 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. The DM74S138 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 a 32-line decoder requires only one inverter. An enable input can be used as a data input for demultiplexing applications. The DM74S139 comprises two separate two-line-to-fourline decoders in a single package. The active-LOW enable input can be used as a data line in demultiplexing applications. All of these decoders/demultiplexers feature 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. Features s Designed specifically for high speed: Memory decoders Data transmission systems s DM74S138 3-to-8-line decoders incorporates 3 enable inputs to simplify cascading and/or data reception s DM74S139 contains two fully independent 2-to-4-line decoders/demultiplexers s Schottky clamped for high performance s Typical propagation delay time (3 levels of logic) DM74S138 8 ns DM74S139 7.5 ns s Typical power dissipation DM74S138 245 mW DM74S139 300 mW Ordering Code: Order Number DM74S138N DM74S139N Package Number N16E N16E Package Description 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide 16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300 Wide (c) 2000 Fairchild Semiconductor Corporation DS006466 www.fairchildsemi.com DM74S138 * DM74S139 Connection Diagrams DM74S138 DM74S139 Function Tables DM74S138 Inputs Enable G1 X L H H H H H H H H H X L L L L L L L L Select XXX XXX L L L L LH H H L H H H H H H H H H H L H H H H H H H H H H L H H H H H Outputs Inputs Enable G H L L L L H H H H H H H L H H H H H H H H H H L H H H H H H H H H H L * G2 = G2A + G2B H = HIGH level L = LOW level X = don't care (either LOW or HIGH logic level) DM74S139 Outputs Y0 H L H H H Y1 H H L H H Y2 H H H L H Y3 H H H H L Select B X L L H H A X L H L H G2* C B A Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 H H H H H L H H H H H H H H H H L H H H LHL LHH HL L HLH HHL HHH Logic Diagrams DM74S138 DM74S139 www.fairchildsemi.com 2 DM74S138 * DM74S139 Absolute Maximum Ratings(Note 1) Supply Voltage Input Voltage Operating Free Air Temperature Range Storage Temperature Range 7V 5.5V 0 C to +70C -65 C to +150 C 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 -1 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 IOS ICC ICC 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 Short Circuit Output Current Supply Current (DM74S138) Supply Current (DM74S139) 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 (Note 3) VCC = Max (Note 4) VCC = Max (Note 4) -40 49 60 2.7 3.4 0.5 1 50 -2 -100 74 90 Min Typ (Note 2) Max -1.2 Units V V V mA 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 enabled and OPEN. 3 www.fairchildsemi.com DM74S138 * DM74S139 DM74S138 Switching Characteristics at VCC = 5V and TA = 25C RL = 280 Symbol tPLH tPHL tPLH tPHL tPLH tPHL tPLH tPHL 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 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 From (Input) To (Output) Select to Output Select to Output Select to Output Select to Output Enable to Output Enable to Output Enable to Output Enable to Output Levels of Delay 2 2 3 3 2 2 3 3 CL = 15 pF Min Max 7 10.5 12 12 8 11 11 11 CL = 50 pF Min Max 9 14 14 15 10 14 13 14 ns ns ns ns ns ns ns ns Units DM74S139 Switching Characteristics at VCC = 5V and TA = 25C RL = 280 Symbol tPLH tPHL tPLH tPHL tPLH tPHL 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 Propagation Delay Time LOW-to-HIGH Level Output Propagation Delay Time HIGH-to-LOW Level Output From (Input) To (Output) Select to Output Select to Output Select to Output Select to Output Enable to Output Enable to Output Levels of Delay 2 2 3 3 2 2 CL = 15 pF Min Max 7.5 10 12 12 8 10 CL = 50 pF Min Max 10 13 13 15 10 13 ns ns ns ns ns ns Units www.fairchildsemi.com 4 DM74S138 * DM74S139 Decoder/Demultiplexer 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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