SN54/74LS138 1-OF-8 DECODER/ DEMULTIPLEXER The LSTTL / MSI SN54 / 74LS138 is a high speed 1-of-8 Decoder / Demultiplexer. This device is ideally suited for high speed bipolar memory chip select address decoding. The multiple input enables allow parallel expansion to a 1-of-24 decoder using just three LS138 devices or to a 1-of-32 decoder using four LS138s and one inverter. The LS138 is fabricated with the Schottky barrier diode process for high speed and is completely compatible with all Motorola TTL families. • • • • • 1-OF-8 DECODER/ DEMULTIPLEXER LOW POWER SCHOTTKY Demultiplexing Capability Multiple Input Enable for Easy Expansion Typical Power Dissipation of 32 mW Active Low Mutually Exclusive Outputs Input Clamp Diodes Limit High Speed Termination Effects J SUFFIX CERAMIC CASE 620-09 CONNECTION DIAGRAM DIP (TOP VIEW) 16 1 NOTE: The Flatpak version has the same pinouts (Connection Diagram) as the Dual In-Line Package. N SUFFIX PLASTIC CASE 648-08 16 1 PIN NAMES A0 – A2 E1, E2 E3 O0 – O7 Address Inputs Enable (Active LOW) Inputs Enable (Active HIGH) Input Active LOW Outputs (Note b) HIGH LOW 0.5 U.L. 0.5 U.L. 0.5 U.L. 10 U.L. 0.25 U.L. 0.25 U.L. 0.25 U.L. 5 (2.5) U.L. NOTES: a) 1 TTL Unit Load (U.L.) = 40 µA HIGH/1.6 mA LOW. b) The Output LOW drive factor is 2.5 U.L. for Military (54) and 5 U.L. for Commercial (74) Temperature Ranges. LOGIC DIAGRAM D SUFFIX SOIC CASE 751B-03 LOADING (Note a) 1 ORDERING INFORMATION SN54LSXXXJ SN74LSXXXN SN74LSXXXD Ceramic Plastic SOIC LOGIC SYMBOL 16 FAST AND LS TTL DATA 5-230 SN54/74LS138 FUNCTIONAL DESCRIPTION The LS138 is a high speed 1-of-8 Decoder/Demultiplexer fabricated with the low power Schottky barrier diode process. The decoder accepts three binary weighted inputs (A0, A1, A2) and when enabled provides eight mutually exclusive active LOW Outputs (O0 – O7). The LS138 features three Enable inputs, two active LOW (E1, E2) and one active HIGH (E3). All outputs will be HIGH unless E1 and E2 are LOW and E3 is HIGH. This multiple enable function allows easy parallel ex- pansion of the device to a 1-of-32 (5 lines to 32 lines) decoder with just four LS138s and one inverter. (See Figure a.) The LS138 can be used as an 8-output demultiplexer by using one of the active LOW Enable inputs as the data input and the other Enable inputs as strobes. The Enable inputs which are not used must be permanently tied to their appropriate active HIGH or active LOW state. TRUTH TABLE INPUTS OUTPUTS E1 E2 E3 A0 A1 A2 O0 O1 O2 O3 O4 O5 O6 O7 H X X L L L L L L L L X H X L L L L L L L L X X L H H H H H H H H X X X L H L H L H L H X X X L L H H L L H H X X X L L L L H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H H H H H H H H H H H L H = HIGH Voltage Level L = LOW Voltage Level X = Don’t Care A0 A1 A2 LS04 A3 A4 H 123 A0 A1 A2 E 123 A0 A1 A2 123 E A0 A1 A2 E 123 A0 A1 A2 E LS138 LS138 LS138 LS138 O0 O1 O2 O3 O4 O5 O6 O7 O0 O1 O2 O3 O4 O5 O6 O7 O0 O1 O2 O3 O4 O5 O6 O7 O0 O1 O2 O3 O4 O5 O6 O7 O0 O31 Figure a FAST AND LS TTL DATA 5-231 SN54/74LS138 GUARANTEED OPERATING RANGES Symbol Parameter Min Typ Max Unit VCC Supply Voltage 54 74 4.5 4.75 5.0 5.0 5.5 5.25 V TA Operating Ambient Temperature Range 54 74 – 55 0 25 25 125 70 °C IOH Output Current — High 54, 74 – 0.4 mA IOL Output Current — Low 54 74 4.0 8.0 mA DC CHARACTERISTICS OVER OPERATING TEMPERATURE RANGE (unless otherwise specified) Limits Symbol Parameter VIH Input HIGH Voltage VIL Input LOW Voltage VIK Input Clamp Diode Voltage VOH Output HIGH Voltage VOL Output LOW Voltage IIH Input HIGH Current IIL Input LOW Current IOS Short Circuit Current (Note 1) ICC Power Supply Current Min Typ Unit Max 2.0 54 0.7 74 0.8 – 0.65 – 1.5 Test Conditions V Guaranteed Input HIGH Voltage for All Inputs V Guaranteed Input LOW Voltage for All Inputs V VCC = MIN, IIN = – 18 mA 54 2.5 3.5 V 74 2.7 3.5 V VCC = MIN, IOH = MAX, VIN = VIH or VIL per Truth Table VCC = VCC MIN, VIN = VIL or VIH per Truth Table 54, 74 0.25 0.4 V IOL = 4.0 mA 74 0.35 0.5 V IOL = 8.0 mA 20 µA VCC = MAX, VIN = 2.7 V 0.1 mA VCC = MAX, VIN = 7.0 V – 20 – 0.4 mA VCC = MAX, VIN = 0.4 V –100 mA VCC = MAX 10 mA VCC = MAX Note 1: Not more than one output should be shorted at a time, nor for more than 1 second. AC CHARACTERISTICS (TA = 25°C) Symbol Levels of Delay Parameter Limits Min Typ Max Unit tPLH tPHL Propagation Delay Address to Output 2 2 13 27 20 41 ns tPLH tPHL Propagation Delay Address to Output 3 3 18 26 27 39 ns tPLH tPHL Propagation Delay E1 or E2 Enable to Output 2 2 12 21 18 32 ns tPLH tPHL Propagation Delay E3 Enable to Output 3 3 17 25 26 38 ns Test Conditions VCC = 5.0 V CL = 15 pF AC WAVEFORMS Figure 1 Figure 2 FAST AND LS TTL DATA 5-232 Case 751B-03 D Suffix 16-Pin Plastic SO-16 -A- "! ! " " ! " # 1 %# ) ! !" $ !" 8 C -T- D M K " ! #! J F ! Case 648-08 N Suffix 16-Pin Plastic R X 45° G " ! ) #! P ! " " 9 -B- ! 16 & ! ! ° ° ° ° ( ( ( ( "! ! " " ! ! ' " " ! ' ! " # & -A- 16 9 1 8 ! ! $ ! B # ) " ! " # ) !" $ !" ) F L C S -T- K H G M J D " Case 620-09 J Suffix 16-Pin Ceramic Dual In-Line -A- ! ! ! ! ° ° ° ° "! ! " 16 " ) " L K M N J G D " $ " $ ! " " ! ! FAST AND LS TTL DATA 5-233 & # ) !" $ !" ) -T $ " " C F & 8 E ! ! ! " " -B1 & 9 * * ! ! ! ! * * ! ° ° ! ° ° Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters can and do vary in different applications. All operating parameters, including “Typicals” must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of others. 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Literature Distribution Centers: USA: Motorola Literature Distribution; P.O. Box 20912; Phoenix, Arizona 85036. EUROPE: Motorola Ltd.; European Literature Centre; 88 Tanners Drive, Blakelands, Milton Keynes, MK14 5BP, England. JAPAN: Nippon Motorola Ltd.; 4-32-1, Nishi-Gotanda, Shinagawa-ku, Tokyo 141, Japan. ASIA PACIFIC: Motorola Semiconductors H.K. Ltd.; Silicon Harbour Center, No. 2 Dai King Street, Tai Po Industrial Estate, Tai Po, N.T., Hong Kong. ◊ FAST AND LS TTL DATA 5-234