unisonic technologies co., ltd u74hct138 cmos ic www.unisonic.com.tw 1 of 5 copyright ? 2011 unisonic technologies co., ltd qw-r502-642.a 3-to-8 line decoders / demultiplexers ? description the u74hct138 decodes a three ? bit address to 1 ? of ? 8 active ? low outputs. this device features three chip select inputs, two active ? low and one active ? high, to facilitate the demultiplexing, cascading and chip ? selecting functions. the demultiplexing function is accomplished by using the address inputs to select the desired device output. one of the chip selects is used as a data input while the other chip selects are held in their active states. ? features * operate from 4.5v to 5.5v * low input current:1.0ua max * low power consumption: 8 a max * typical t pd =15ns * inputs are ttl voltage compatible ? ordering information ordering number lead free halogen free package packing u74hct138l-s16-r U74HCT138G-S16-R sop-16 tape reel u74hct138l-s16-t u74hct138g-s16-t sop-16 tube
u74hct138 cmos ic unisonic technologies co., ltd 2 of 5 www.unisonic.com.tw qw-r502-642.a ? pin configuration 7 6 5 4 3 2 1 14 13 12 10 11 15 16 a0 a1 a2 e3 v cc 8 9 gnd e1 e2 y7 y6 y5 y4 y3 y2 y1 y0 ? function table inputs outputs e1 e2 e3 a0 a1 a2 y0 y1 y2 y3 y4 y5 y6 y7 h x x x x x h h h h h h h h x h x x x x h h h h h h h h x x l x x x h h h h h h h h l l h l l l l h h h h h h h l l h h l l h l h h h h h h l l h l h l h h l h h h h h l l h h h l h h h l h h h h l l h l l h h h h h l h h h l l h h l h h h h h h l h h l l h l h h h h h h h h l h l l h h h h h h h h h h h l note:h : high voltage level l : low voltage level x : don?t care
u74hct138 cmos ic unisonic technologies co., ltd 3 of 5 www.unisonic.com.tw qw-r502-642.a ? logic symbol ? logic diagram y1 y0 y2 y3 y4 y5 y6 y7 e1 e2 e3 a0 a1 a2
u74hct138 cmos ic unisonic technologies co., ltd 4 of 5 www.unisonic.com.tw qw-r502-642.a ? absolute maximum rating parameter symbol ratings unit supply voltage v cc -0.5 ~ 7.0 v input clamp current(v i <0 or v i >v cc ) i ik 20 ma output clamp current(v o <0 or v o >v cc ) i ok 20 ma continuous output current(v o =0 to v cc ) i o 25 ma v cc or gnd current i cc 50 ma storage temperature t stg -65 ~ + 150 note: absolute maximum ratings are those values be yond which the device could be permanently damaged. absolute maximum ratings are stress ratings only and functional device oper ation is not implied. ? recommended operating conditions parameter symbol test conditions min typ max unit supply voltage v cc operating 4.5 5.0 5.5 v input voltage v in 0 v cc v output voltage v out 0 v cc v operating temperature t a -40 +85 input rise or fall times t r , t f v cc =4.5v~5.5v 500 ns ? electrical characteristics (t a =25 ) parameter symbol test conditions min typ max unit high-level input voltage v ih v cc =4.5v~5.5v 2.0 v low-lever output voltage v il v cc =4.5v~5.5v 0.8 v v cc =4.5v, i oh =-20 a 4.4 4.499 v high-level output voltage v oh v cc =4.5v, i oh =-4ma 3.98 4.3 v v cc =4.5v, i ol =20 a 0.001 0.1 v low-level output voltage v ol v cc =4.5v, i ol =4ma 0.17 0.26 v input leakage current i i(leak) v cc =5.5v, v in = v cc or gnd 0.1 100 na quiescent supply current i cc v cc =5.5v, v in =v cc or gnd, i out =0 8 a additional quiescent supply current i cc one input at 0.5v or 2.4v,other inputs at 0 or vcc 1.4 2.4 ma input capacitance c i v cc =4.5v~5.5v 3 10 pf ? switching characteristics (t a =25 ,see test circuit and waveforms) parameter symbol test conditions min typ max unit v cc =4.5v, c l =50pf 23 36 ns propagation delay from input (an) to output( yn ) t plh /t phl v cc =5.5v, c l =50pf 17 32 ns v cc =4.5v, c l =50pf 22 33 ns propagation delay from input ( en ) to output( yn ) t plh /t phl v cc =5.5v, c l =50pf 18 30 ns v cc =4.5v, c l =50pf 12 15 ns output transition time t tlh /t thl v cc =5.5v, c l =50pf 11 14 ns ? operating characteristics parameter symbol test conditions min typ max unit power dissipation capacitance c pd no load 85 pf
u74hct138 cmos ic unisonic technologies co., ltd 5 of 5 www.unisonic.com.tw qw-r502-642.a ? test circuit and waveforms test circuit propagation delay and output tansition times note: c l includes probe and jig capacitance. all input pulses are supplied by generators having the following characteristics: zo = 50 ? , t r =6ns, t f =6ns. utc assumes no responsibility for equipment failures that result from using products at values that exceed, even momentarily, rated values (such as maximum ratings, operating condition ranges, or other parameters) listed in products specifications of any and all utc products described or contained herein. utc products are not designed for use in life support appliances, devices or systems where malfunction of these products can be reasonably expected to result in personal injury. reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. the information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice.
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