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1/11 april 2001 n high speed: t pd = 4.5ns (typ.) at v cc =5v n low power dissipation: i cc =4 m a(max.) at t a =25 c n high noise immunity: v nih =v nil =28%v cc (min.) n 50 w transmission line driving capability n symmetrical output impedance: |i oh |=i ol = 24ma (min) n balanced propagation delays: t plh @ t phl n operating voltage range: v cc (opr) = 2v to 6v n pin and function compatible with 74 series 257 n improved latch-up immunity description the 74ac257 is an advanced high-speed cmos quad 2-channel multiplexer (3-state) fabricated with sub-micron silicon gate and double-layer metal wiring c 2 mos tecnology. it is composed of four independent 2-channel multiplexer with common select and enable (oe) inputs. it is a non-inverting multiplexer. when the oe input is held high,all the output become in high impedance state. if select input is held low, oao data is selected, when select input is held high, obo data is chosen. all inputs and outputs are equipped with protection circuits against static discharge, giving them 2kv esd immunity and transient excess voltage. 74ac257 quad 2 channel multiplexer (3-state) pin connection and iec logic symbols order codes package tube t & r dip 74ac257b sop 74ac257m 74AC257MTR tssop 74ac257ttr tssop dip sop
74ac257 2/11 input and output equivalent circuit pin description truth table x : don't care z : high impedance logic diagram this logic diagram has not be used to estimate propagation delays pin no symbol name and function 1 select common data select inputs 2, 5, 11, 14 1a to 4a data inputs from source a 3, 6, 10, 13 1b to 4b data inputs from source b 4, 7, 9, 12 1y to 4y multiplexer outputs 15 oe 3 state output enable inputs (active low) 8 gnd ground (0v) 16 v cc positive supply voltage inputs output oe select a b y hxxxl lllxl llhxh lhxll lhxhh
74ac257 3/11 absolute maximum ratings absolute maximum ratings are those values beyond which damage to the device may occur. functional operation under these conditions is not implied. recommended operating conditions 1) v in from 30% to 70% of v cc symbol parameter value unit v cc supply voltage -0.5 to +7 v v i dc input voltage -0.5 to v cc + 0.5 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 50 ma i cc or i gnd dc v cc or ground current 200 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 2to6 v v i input voltage 0 to v cc v v o output voltage 0 to v cc v t op operating temperature -55 to 125 c dt/dv input rise and fall time v cc = 3.0, 4.5 or 5.5v (note 1) 8 ns/v
74ac257 4/11 dc specifications 1) maximum test duration 2ms, one output loaded at time 2) incident wave switching is guaranteed on transmission lines with impedances as low as 50 w symbol parameter test condition value unit v cc (v) t a =25 c -40 to 85 c -55 to 125 c min. typ. max. min. max. min. max. v ih high level input voltage 3.0 v o = 0.1 v or v cc -0.1v 2.1 1.5 2.1 2.1 v 4.5 3.15 2.25 3.15 3.15 5.5 3.85 2.75 3.85 3.85 v il low level input voltage 3.0 v o = 0.1 v or v cc -0.1v 1.5 0.9 0.9 0.9 v 4.5 2.25 1.35 1.35 1.35 5.5 2.75 1.65 1.65 1.65 v oh high level output voltage 3.0 i o =-50 m a 2.9 2.99 2.9 2.9 v 4.5 i o =-50 m a 4.4 4.49 4.4 4.4 5.5 i o =-50 m a 5.4 5.49 5.4 5.4 3.0 i o =-12 ma 2.56 2.46 2.4 4.5 i o =-24 ma 3.86 3.76 3.7 5.5 i o =-24 ma 4.86 4.76 4.7 v ol low level output voltage 3.0 i o =50 m a 0.002 0.1 0.1 0.1 v 4.5 i o =50 m a 0.001 0.1 0.1 0.1 5.5 i o =50 m a 0.001 0.1 0.1 0.1 3.0 i o =12 ma 0.36 0.44 0.5 4.5 i o =24 ma 0.36 0.44 0.5 5.5 i o =24 ma 0.36 0.44 0.5 i i input leakage current 5.5 v i =v cc or gnd 0.1 1 1 m a ioz high impedance output leakage current 5.5 v i =v ih or v il v o =v cc or gnd 0.5 5 10 m a i cc quiescent supply current 5.5 v i =v cc or gnd 44080 m a i old dynamic output current (note 1, 2) 5.5 v old = 1.65 v max 75 50 ma i ohd v ohd = 3.85 v min -75 -50 ma
74ac257 5/11 ac electrical characteristics (c l = 50 pf, r l = 500 w , input t r =t f = 3ns) (*) voltage range is 3.3v 0.3v (**) voltage range is 5.0v 0.5v capacitive characteristics 1) c pd is defined as the value of the ic's 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 xv cc xf in +i cc /4 (per circuit) symbol parameter test condition value unit v cc (v) t a =25 c -40 to 85 c -55 to 125 c min. typ. max. min. max. min. max. t plh t phl propagation delay time a, b to y 3.3 (*) 1.5 5.5 8.5 1.5 9.0 1.5 9.0 ns 5.0 (**) 1.5 4.5 6.0 1.5 7.0 1.5 7.0 t plh t phl propagation delay time select to y 3.3 (*) 1.5 7.0 10.5 1.5 11.5 1.5 11.5 ns 5.0 (**) 1.5 5.5 7.5 1.5 8.5 1.5 8.5 t pzl t pzh output enable time 3.3 (*) 1.5 5.5 9.0 1.5 100 1.5 100 ns 5.0 (**) 1.5 4.5 7.5 1.5 8.5 1.5 8.5 t plz t phz output disable time 3.3 (*) 1.5 7.0 10.0 1.5 11.0 1.5 13.0 ns 5.0 (**) 1.5 5.5 9.0 1.5 10.0 1.5 11.0 symbol parameter test condition value unit v cc (v) t a =25 c -40 to 85 c -55 to 125 c min. typ. max. min. max. min. max. c in input capacitance 5.0 5 pf c out output capacitance 5.0 8 pf c pd power dissipation capacitance (note 1) 5.0 f in = 10mhz 20 pf
74ac257 6/11 test circuit c l = 50pf or equivalent (includes jig and probe capacitance) r l =r 1 = 500 w or equivalent r t =z out of pulse generator (typically 50 w ) waveform 1: propagation delays for inverting conditions (f=1mhz; 50% duty cycle) test switch t plh ,t phl open t pzl ,t plz 2v cc t pzh ,t phz open
74ac257 7/11 waveform 2: propagation delays for non-inverting conditions (f=1mhz; 50% duty cycle) waveform 3: output enable and disable time (f=1mhz; 50% duty cycle)
74ac257 8/11 dim. mm inch min. typ. max. min. typ. max. a1 0.51 0.020 b 0.77 1.65 0.030 0.065 b 0.5 0.020 b1 0.25 0.010 d 20 0.787 e 8.5 0.335 e 2.54 0.100 e3 17.78 0.700 f 7.1 0.280 i 5.1 0.201 l 3.3 0.130 z 1.27 0.050 p001c plastic dip-16 (0.25) mechanical data
74ac257 9/11 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
74ac257 10/11 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
74ac257 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 infringe ment of patents or other righ ts 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. specifications mentioned in this pub lication are subject to change without notice. thi s pub lication supersedes and replaces all information previously supplied. stmicroelectronics prod ucts are not authori zed for use as critical components in life suppo rt 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 - swit zerland - united kingdom ? http://w ww.st.com 11/11

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