1/9 june 2001 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 =25c n compatible with ttl outputs: v ih = 2v (min.), v il = 0.8v (max) n power down protection on inputs & outputs 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) = 4.5v to 5.5v n pin and function compatible with 74 series 238 n improved latch-up immunity description the 74vhct238a 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. when 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. the three enable inputs are provided to ease cascade connection and application of address decoders for memory systems. power down protection is provided on all inputs and outputs 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 since all inputs are equipped with ttl threshold. all inputs and outputs are equipped with protection circuits against static discharge, giving them 2kv esd immunity and transient excess voltage. 74vhct238a 3 to 8 line decoder pin connection and iec logic symbols order codes package tube t & r sop 74vhct238am 74VHCT238AMTR tssop 74vhct238attr tssop sop
74vhct238a 2/9 input equivalent circuit pin description truth table x : dont care logic diagram this logic diagram has not be used to estimate propagation delays 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 inputs outputs enable select g2b g2a g1 c b a y0 y1 y2 y3 y4 y5 y6 y7 xxlxxxllllllll xhxxxx llllllll hxxxxx llllllll llhlllhlllllll llhllhlhlll lll llhlhlllhll lll llhlhhlllhl lll llhhllllllhlll llhhlhlllllhll llhhhlllllllhl l lhhhh lllllllh
74vhct238a 3/9 absolute maximum ratings absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditi ons is not implied 1) v cc = 0v 2) high or low state recommended operating conditions 1) v cc = 0v 2) high or low state 3) vin from 0.8v to 2v 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 (see note 1) -0.5 to +7.0 v v o dc output voltage (see note 2) -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 50 ma t stg storage temperature -65 to +150 c t l lead temperature (10 sec) 300 c symbol parameter value unit v cc supply voltage 4.5 to 5.5 v v i input voltage 0 to 5.5 v v o output voltage (see note 1) 0 to 5.5 v v o output voltage (see note 2) 0 to v cc v t op operating temperature -55 to 125 c dt/dv input rise and fall time (see note 3) (v cc = 5.0 0.5v) 0 to 20 ns/v
74vhct238a 4/9 dc specifications ac electrical characteristics (input t r = t f = 3ns) (*) voltage range is 5.0v 0.5v capacitive characteristics 1) c pd is defined as the value of the ics internal equivalent capacitance which is calculated from the operating current consumption without load. (refer to test circuit). average operating current can be obtained by the following equation. i cc(opr) = c pd x v cc x f in + i cc symbol parameter test condition value unit v cc (v) t a = 25c -40 to 85c -55 to 125c min. typ. max. min. max. min. max. v ih high level input voltage 4.5 to 5.5 222v v il low level input voltage 4.5 to 5.5 0.8 0.8 0.8 v v oh high level output voltage 4.5 i o =-50 m a 4.4 4.5 4.4 4.4 v 4.5 i o =-8 ma 3.94 3.8 3.7 v ol low level output voltage 4.5 i o =50 m a 0.0 0.1 0.1 0.1 v 4.5 i o =8 ma 0.36 0.44 0.55 i i input leakage current 0 to 5.5 v i = 5.5v or gnd 0.1 1.0 1.0 m a i cc quiescent supply current 5.5 v i = v cc or gnd 44040 m a i cc additional worst case supply current 5.5 one input at 3.4v, other input at v cc or gnd 1.35 1.5 1.5 ma i opd output leakage current 0 v out = 5.5v 0.5 5.0 5.0 m a symbol parameter test condition value unit v cc (*) (v) c l (pf) t a = 25c -40 to 85c -55 to 125c min. typ. max. min. max. min. max. t plh t phl propagation delay time a,b,c to y 5.0 15 5.5 8.1 1.0 9.5 1.0 9.5 ns 5.0 50 7.0 10.1 1.0 11.5 1.0 11.5 t plh t phl propagation delay time g1 to y 5.0 15 5.4 8.1 1.0 9.5 1.0 9.5 ns 5.0 50 6.9 10.1 1.0 11.5 1.0 11.5 t plh t phl propagation delay time g2a , g2b to y 5.0 15 5.7 8.1 1.0 9.5 1.0 9.5 ns 5.0 50 7.2 10.1 1.0 11.5 1.0 11.5 symbol parameter test condition value unit t a = 25c -40 to 85c -55 to 125c min. typ. max. min. max. min. max. c in input capacitance 6101010pf c pd power dissipation capacitance (note 1) 37 pf
74vhct238a 5/9 test circuit c l =15/50pf or equivalent (includes jig and probe capacitance) r t = z out of pulse generator (typically 50 w ) waveform 1: propagation delays for inverting outputs (f=1mhz; 50% duty cycle)
74vhct238a 6/9 waveform 2: propagation delays for non-inverting outputs (f=1mhz; 50% duty cycle)
74vhct238a 7/9 dim. mm. inch min. typ max. min. typ. max. a 1.75 0.068 a1 0.1 0.2 0.003 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 s8 (max.) so-16 mechanical data po13h
74vhct238a 8/9 dim. mm. inch min. typ max. min. typ. max. a 1.2 0.047 a1 0.05 0.15 0.002 0.004 0.006 a2 0.8 1 1.05 0.031 0.039 0.041 b 0.19 0.30 0.007 0.012 c 0.09 0.20 0.004 0.0089 d 4.9 5 5.1 0.193 0.197 0.201 e 6.2 6.4 6.6 0.244 0.252 0.260 e1 4.3 4.4 4.48 0.169 0.173 0.176 e 0.65 bsc 0.0256 bsc k0 80 8 l 0.45 0.60 0.75 0.018 0.024 0.030 tssop16 mechanical data c e b a2 a e1 d 1 pin 1 identification a1 l k e 0080338d
74vhct238a 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 f rom its use. no license is granted by implication or otherwise under any patent or patent rights of stmicroelectronics. specificati ons 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 ? 2001 stmicroelectronics - printed in italy - all rights reserved stmicroelectronics group of companies australia - brazil - china - finland - france - germany - hong kong - india - italy - japan - malaysia - malta - morocco singapore - spain - sweden - switzerland - united kingdom ? http://www.st.com 9/9
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