74HC138

深圳市富满电子有限公司 SHENZHEN FUMAN ELECTRONICS CO., LTD. 74HC138(文件编号：S&CIC0503) 3-to-8 Line Decoder/Demultiplexer; Inverting weighted address inputs (A0, A1, A2) and when enabled, FEATURES provide 8 mutually exclusive active LOW outputs (Y0 to Demultiplexing capability Y7). Multiple input enable for easy expansion The “138” features three enable inputs: two active LOW Ideal for memory chip select decoding (E1 and E2) and one active HIGH (E3). Every output will be Active LOW mutually exclusive outputs HIGH unless E1 and E2 are LOW and E3 is HIGH. Output capability: standard This multiple enable function allows easy parallel ICC category: MSI expansion of the “138” to a 1-of-32 (5 lines to 32 lines) decoder with just four “138” ICs and one inverter. GENERAL DESCRIPTION The ”138” can be used as an eight output demultiplexer by The 74HC138 are high-speed Si-gate CMOS devices using one of the active LOW enable inputs as the data and are pin compatible with low power Scotty TTL input and the remaining enable inputs as strobes. Unused (LSTTL). They are specified in compliance with JEDEC enable inputs must be permanently tied to their standard no. 7A. appropriate active HIGH or LOW state. The 74HC138 decoders accept three binary The ”138” is identical to the “238” but has inverting outputs. QUICK REFERENCE DATA GND = 0 V; Tamb = 25 C; tr = tf = 6 ns SYMBOL PARAMETER CPMDITIONS TYPICAL HC HCT UNIT Propagation delay tPHL/ tPLH An to Yn tPHL/ tPLH E3 to Yn CL=15pF; Vcc=5V 12 14 En to Yn Cl Input capacitance CPD Power dissipation capacitance per package Notes 1. CPD is used to determine the dynamic power dissipation (PD in W): PD = CPD VCC2 fi (CL VCC2 fo) where: fi = input frequency in MHz fo = output frequency in MHz (CL VCC2 fo) = sum of outputs CL = output load capacitance in pF VCC = supply voltage in V 2. For HC the condition is VI = GND to VCC For HCT the condition is VI = GND to VCC 1.5 V ORDERING INFORMATION See 第 1 页 共 5 页 Notes 1 and 2 17 19 ns ns 3.5 3.5 pF 67 67 pF 深圳市富满电子有限公司 SHENZHEN FUMAN ELECTRONICS CO., LTD. 74HC138(文件编号：S&CIC0503) 3-to-8 Line Decoder/Demultiplexer; Inverting PIN DESCRIPTION PIN NO 1, 2, 3 4, 5 6 8 15, 14, 13, 12, 11, 10, 9, 7 16 SYMBOL A0 to A2 E1, E2 E3 GND Yo to Y7 Vcc NAME AND FUNCTION Address inputs Enable inputs (active LOW) Enable input (active HIGH) Ground (0V) Outputs (active LOW) Positive supply voltage 第 2 页 共 5 页 深圳市富满电子有限公司 SHENZHEN FUMAN ELECTRONICS CO., LTD. 74HC138(文件编号：S&CIC0503) 3-to-8 Line Decoder/Demultiplexer; Inverting FUNCTION TABLE INPUTS OUTPUTS E1 E2 E3 A0 A1 A2 Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7 H X X X H X X X L X X X X X X X X X H H H H H H H H H H H H H H H H H H H H H H H H L L L L L L L L L L L L L L L L H H H H H H H H L H L H L H L H L L H H L L H H L L L L H H H H L H H H H H H H H L H H H H H H H H L H H H H H H H H L H H H H H H H H L H H H H H H H H L H H H H H H H H L H H H H H H H H L Notes 1. H = HIGH voltage level L = LOW voltage level X = don’t care 第 3 页 共 5 页 深圳市富满电子有限公司 SHENZHEN FUMAN ELECTRONICS CO., LTD. 74HC138(文件编号：S&CIC0503) 3-to-8 Line Decoder/Demultiplexer; Inverting DC CHARACTERISTICS FOR 74HC For the DC characteristics see Output capability: standard ICC category: MSI AC CHARACTERISTICS FOR 74HC GND = 0 V; tr = tf = 6 ns; CL = 50 Pf Tamb(℃) SYMBOL 74HC PARAMETER +25 min tPHL/ tPLH tPHL/ tPLH tPHL/ tPLH tTHL/ tTLH TEST CONDITIONS Propagation delay An to Yn Propagation delay E3 to Yn Propagation delay En to Yn Output transition time -40 to +85 -40 to +125 min min max UNIT Vcc (v) typ max 41 150 190 225 15 30 38 45 12 26 33 38 6.0 47 150 190 225 2.0 17 30 38 45 14 26 33 38 6.0 47 150 190 225 2.0 17 30 38 45 14 26 33 38 6.0 19 75 95 110 2.0 7 15 19 22 6 13 16 19 WAVEFORMS max 2.0 ns ns ns ns 4.5 4.5 4.5 4.5 Fig. 6 Fig. 6 Fig. 7 Fig. 6 and 7 6.0 DC CHARACTERISTICS FOR 74HCT For the DC characteristics see Output capability: standard ICC category: MSI Note to HCT types The value of additional quiescent supply current (ICC) for a unit load of 1 is given in the family specifications. To determine ICC per input, multiply this value by the unit load coefficient shown in the table below. INPUT UNIT LOAD COEFFICIENT An 1.50 En 1.25 E3 1.00 第 4 页 共 5 页 深圳市富满电子有限公司 SHENZHEN FUMAN ELECTRONICS CO., LTD. 74HC138(文件编号：S&CIC0503) 3-to-8 Line Decoder/Demultiplexer; Inverting AC CHARACTERISTICS FOR 74HCT GND = 0 V; tr = tf = 6 ns; CL = 50 pF Tamb(℃) SYMBOL 74HCT PARAMETER +25 min tPHL/ tPLH Propagation delay TEST CONDITIONS -40 to +85 -40 to +125 min min max UNIT Vcc (v) WAVEFORMS typ max max 20 35 44 53 ns 4.5 Fig. 6 18 40 50 60 ns 4.5 Fig. 6 19 40 50 60 ns 4.5 Fig. 7 7 15 19 22 ns 4.5 Fig. 6 and 7 An to Yn tPHL/ tPLH Propagation delay E3 to Yn tPHL/ tPLH Propagation delay En to Yn tTHL/ tTLH Output transition time AC WAVEFORMS 第 5 页 共 5 页