74VHC238 3 to 8 line decoder october 1998 n high speed: t pd =5.5 ns (typ.) at v cc =5v n low power dissipation: i cc =4 m a (max.) at t a =25 o c n high noise immunity: v nih =v nil =28%v cc (min.) n power down protection on inputs n symmetrical output impedance: |i oh |=i ol = 8 ma (min) n balanced propagation delays: t plh @ t phl n operating voltage range: v cc (opr) = 2v to 5.5v n pin and function compatible with 74 series 238 n improved latch-up immunity description the 74VHC238 is an advanced high-speed cmos 3 to 8 line decoder fabricated with sub-micron silicon gate and double-layer metal wiring c 2 mos technology. it has similar high speed performance of equivalent bipolar schottky ttl combined with true cmos low power dissipation. if the device is enabled, 3 binary select inputs (a, b and c) determine which one of the outputs will go high. if enable input g1 is held low or either g2a or g2b is held high, decoding function is inhibited and all the 8 outputs go to low. three enable inputs are provided to ease cascade connection and application of this address decoders for memory systems. power down protection is provided on all inputs and 0 to 7v can be accepted on inputs with no regard to the supply voltage. this device can be used to interface 5v to 3v. all inputs and outputs are equipped with protection circuits against static discharge, giving them 2kv esd immunity and transient excess voltage. pin connection and iec logic symbols m1 (micro package) t (tssop package) order codes : 74VHC238m 74VHC238t ? 1/8
input equivalent circuit logic diagram pin description pin no symbol name and function 1, 2, 3 a, b, c address inputs 4, 5 g2a, g2b enable inputs 6 g1 enable input 15, 14, 13, 12, 11, 10, 9, 7 y0 to y7 outputs 8 gnd ground (0v) 16 v cc positive supply voltage truth table inputs outputs enable select g2bg2ag1 c b a y0y1y2y3y4y5y6y7 xxlxxxllllllll xhxxxxllllllll hxxxxxllllllll llhlllhlllllll llhllhlhllllll llhlhlllhlll ll llhlhhlllhllll llhhllllllhlll llhhlhlllllhll llhhhlllllllhl l lhhhh lllllllh x:don't care this logic diagram has not be used to estimate propagation delays 74VHC238 2/8
absolute maximum ratings symbol parameter value unit v cc supply voltage -0.5 to +7.0 v v i dc input voltage -0.5 to +7.0 v v o dc output voltage -0.5 to v cc + 0.5 v i ik dc input diode current - 20 ma i ok dc output diode current 20 ma i o dc output current 25 ma i cc or i gnd dc v cc or ground current 75 ma t stg storage temperature -65 to +150 o c t l lead temperature (10 sec) 300 o c absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these condition is not implied. recommended operating conditions symbol parameter value unit v cc supply voltage 2.0 to 5.5 v v i input voltage 0 to 5.5 v v o output voltage 0 to v cc v t op operating temperature -40 to +85 o c dt/dv input rise and fall time (see note 1) (v cc =3.3 0.3v) (v cc =5.0 0.5v) 0 to 100 0to20 ns/v ns/v 1) v in from 30% to70%of v cc dc specifications symbol parameter test conditions value unit v cc (v) t a =25 o c -40 to 85 o c min. typ. max. min. max. v ih high level input voltage 2.0 1.5 1.5 v 3.0 to 5.5 0.7v cc 0.7v cc v il low level input voltage 2.0 0.5 0.5 v 3.0 to 5.5 0.3v cc 0.3v cc v oh high level output voltage 2.0 v i (*) = v ih or v il i o =-50 m a 1.9 2.0 1.9 v 3.0 i o =-50 m a 2.9 3.0 2.9 4.5 i o =-50 m a 4.4 4.5 4.4 3.0 i o =-4 ma 2.58 2.48 4.5 i o =-8 ma 3.94 3.8 v ol low level output voltage 2.0 v i (*) = v ih or v il i o =50 m a 0.0 0.1 0.1 v 3.0 i o =50 m a 0.0 0.1 0.1 4.5 i o =50 m a 0.0 0.1 0.1 3.0 i o =4 ma 0.36 0.44 4.5 i o =8 ma 0.36 0.44 i i input leakage current 0 to 5.5 v i = 5.5v or gnd 0.1 1.0 m a i cc quiescent supply current 5.5 v i =v cc or gnd 4 40 m a (*) all outputs loaded. 74VHC238 3/8
capacitive characteristics symbol parameter test conditions value unit t a =25 o c -40 to 85 o c min. typ. max. min. max. c in input capacitance 4 10 10 pf c pd power dissipation capacitance (note 1) 37 pf 1) c pd isdefined as the value of the ic'sinternal equivalent capacitance which is calculated fromthe operating current consumption without load. (refert o test circuit).average operating current can be obtained by the following equation. i cc (opr) = c pd ? v cc ? f in +i cc ac electrical characteristics (input t r =t f =3 ns) symbol parameter test condition value unit v cc (v) c l (pf) t a =25 o c -40 to 85 o c min. typ. max. min. max. t plh t phl propagation delay time a, b, c to y 3.3 (*) 15 8.0 12.3 1.0 14.5 ns 3.3 (*) 50 10.5 15.8 1.0 18.0 5.0 (**) 15 5.5 8.1 1.0 9.5 5.0 (**) 50 7.0 10.1 1.0 11.5 t plh t phl propagation delay time g1 to y 3.3 (*) 15 8.1 12.8 1.0 15.0 ns 3.3 (*) 50 10.6 16.3 1.0 18.5 5.0 (**) 15 5.4 8.1 1.0 9.5 5.0 (**) 50 6.9 10.1 1.0 11.5 t plh t phl propagation delay time g2a, g2b to y 3.3 (*) 15 8.1 12.3 1.0 14.5 ns 3.3 (*) 50 10.6 15.8 1.0 18.0 5.0 (**) 15 5.7 8.1 1.0 9.5 5.0 (**) 50 7.2 10.1 1.0 11.5 (*) voltage range is 3.3v 0.3v (**) voltage range is 5v 0.5v test circuit c l = 15/50 pf or equivalent (includes jig and probe capacitance) r l =r 1 =500 w orequivalent r t =z out of pulse generator (typically 50 w ) 74VHC238 4/8
waveform 2: propagation delays for non-inverting outputs (f=1mhz; 50% duty cycle) waveform 1: propagation delays for inverting outputs (f=1mhz; 50% duty cycle) 74VHC238 5/8
dim. mm inch min. typ. max. min. typ. max. a 1.75 0.068 a1 0.1 0.2 0.004 0.007 a2 1.65 0.064 b 0.35 0.46 0.013 0.018 b1 0.19 0.25 0.007 0.010 c 0.5 0.019 c1 45 (typ.) d 9.8 10 0.385 0.393 e 5.8 6.2 0.228 0.244 e 1.27 0.050 e3 8.89 0.350 f 3.8 4.0 0.149 0.157 g 4.6 5.3 0.181 0.208 l 0.5 1.27 0.019 0.050 m 0.62 0.024 s 8 (max.) p013h so-16 mechanical data 74VHC238 6/8
dim. mm inch min. typ. max. min. typ. max. a 1.1 0.433 a1 0.05 0.10 0.15 0.002 0.004 0.006 a2 0.85 0.9 0.95 0.335 0.354 0.374 b 0.19 0.30 0.0075 0.0118 c 0.09 0.20 0.0035 0.0079 d 4.9 5 5.1 0.193 0.197 0.201 e 6.25 6.4 6.5 0.246 0.252 0.256 e1 4.3 4.4 4.48 0.169 0.173 0.176 e 0.65 bsc 0.0256 bsc k0 o 4 o 8 o 0 o 4 o 8 o l 0.50 0.60 0.70 0.020 0.024 0.028 c e b a2 a e1 d 1 pin 1 identification a1 l k e tssop16 mechanical data 74VHC238 7/8
information furnished is believed to be accurate and reliable. however, stmicroelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specification mentioned in this publication are subject to change without notice. this publication supersedes and replaces all information previously supplied. stmicroelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of stmicroelectronics. the st logo is a registered trademark of stmicroelectronics ? 1998 stmicroelectronics printed in italy all rights reserved stmicroelectronics group of companies australia - brazil - canada - china - france - germany - italy - japan - korea - malaysia - malta - mexico - morocco - the netherlands - singapore - spain - sweden - switzerland - taiwan - thailand - united kingdom - u.s.a. http://www.st.com . 74VHC238 8/8
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