H D v4 4 HC2 3 8 @ 3-to-8-line Decoder /Demultiplexer The HD74HC238 has 3 binary select inputs (A, B, and C). If the device is enabled these inputs determine which one of the eight normally high outputs will go low. Two active tow and one active high enables (G4, Go, and Gap) are provided to ease the cascading of decoders. @ FEATURES @ High Speed Operation: tpg (Select to Y)=15ns typ. (Cz =50pF) @ High Output Current: Fanout of 10 LSTTL Loads @ Wide Operating Voltage: Vog=2~6V @ Low Input Current: 14A max. @ Low Quiescent Supply Current: /og (static)=4uA max. (Ta=25C) @ LOGIC DIAGRAM Gi Crp Gra @ PIN ARRANGEMENT VT oa ! A tony 8L2p8 * vf] c[a;-e npfi] yi Ga [4 4G Yat 13] ve irae as [5 +4 Gee Yah 12 | Y3 Outputs a feo yap ur | va Output Y7 [7H Yr Ys Ys 20] Ys cno[ 3] L__s]v. (Top View) @ FUNCTION TABLE inputs Outputs Enable Select Gi|GralGeal C | B} A | Yo| Yi] Y2] Ya] Ye] Ys] Yo] Y- x|x}H] x] x] x}/LILIJL] LJ LI Ly Ly Ll x}|H| x] x) x] xX L]L/L]LIJ Ly] Ly] Lye Li x |x} x} x} x]LIL}L] Ly] Ly] LI Lyk H/L]L]L]L/L{H|L| LIL) Ly)Ly| Lye H/LiL|L{L]H}LI/ AH] L]LIJL]L_ Lye Hi L]L]L]H]L]L/LIH]J LI] LI Lilie H/|LIL|L}H{H{|L)L]L/H{ LILI LIL HI|LILtH/L]L/L]L]L/L]H}| LIL] Lb H|L]L]H/L]H|LJL} Ly LJ LH) LyLl H/L] LH] H]L]L/ LIL] L]L}] Ly} Hye H|L]L]H|H|H/L]L]L}/L]|L}] Ll} Ly) 179 HD74HC238 Mi DC CHARACTERISTICS Ta =25C Ta =40~ +85C : Item Symbol Test Conditions Unit Vec(V) min typ max min max 2.0 1.5 _ _ 1.5 _ Vin 4.5 3.15 _ | 3.15 _ Vv 6.0 4.2 _ ~ 4.2 _ Input Voltage 2.0 = = 05 a 05 Vin 4.5 _ _ 1.35 | 1.35 v 6.0 ~ _ 1.8 _ 1.8 2.0 1.9 | 2.0 _ 1.9 _ 4.5 Tor=20HA 4.4 4.5 _ 4.4 - Vou 6.0 Vi.=Vin or Viz 5.9] 6.0 _ 5.9 _ v 4.5 Ton = 4mA 4.18 _ _ 4.13 _ Output Voltage 6.0 Ton=5.2mA 5.68 _ | 5.63 _ 2.0 | 0.0 0.1 _ 0.1 4.5 Tor =20KA | 0.0 0.1 - 0.1 Vou 6.0 Via=Vin or Vin a 0.0 0.1 _ 0.1 Vv 4.5 Tor. =4mA | 0.26 | 0.33 6.0 Tor. =5.2mA _ | 0.26 | 0.33 Input Current Le 6.0 Vi.=Vcc or GND _ - +0.1 | +1.0] A Quiescent Supply Current | Jec 6.0 Vin=Vee or GND, Iur= OKA - - 4.0 - 40 | A Mi AC CHARACTERISTICS (C1 =50pF, Input t-=;=6ns) . .. Ta=25C Ta= 40~ + 85C . Item Symbol -- Test Conditions - - Unit Vec(V) min typ. | max. | min. | max. 2.0 - - 150 - 190 4.5 Select to Y - 15 30 _ 38 ns Propagation Delay Time {Pua 6.0 26 38 t PHL 2.0 - _ 150 _ 190 45 Enable to Y - 13 30 - 38 ns 6.0 ~_ _ 26 - 33 2.0 _ _ 75 - 95 Output Rise Fall Time tren TS - 5] ib] 19 | ns (THe EO ft = 3 | 16 Input Capacitance Cin _ _ 5 10 _ 10 pF 180