technical data in74ac257 quad 2-input data selector/multiplexer with 3-state outputs high-speed silicon-gate cmos ordering information in74ac257n plastic IN74AC257D soic t a = -40 to 85 c for all packages the in74ac257 is identical in pinout to the ls/als257, hc/hct257. the device inputs are compatible with standard cmos outputs; with pullup resistors, they are compatible with ls/als outputs. this device selects a (4-bit) nibble from either the a or b inputs as determined by the select input. the nibble is presented at the outputs in noninverted from when the output enable pin is at a low level. a high level on the output enable pin switches the outputs into the high- impedance state. ? outputs directly interf ace to cmos, nmos, and ttl ? operating voltage range: 2.0 to 6.0 v ? low input current: 1.0 a; 0.1 a @ 25 c ? high noise immunity characteristic of cmos devices ? output source/sink 24 ma pin assignment logic diagram pin 16 =v cc pin 8 = gnd function table inputs outputs output enable select y0-y3 h x z l l a0-a3 l h b0-b3 x=don?t care z = high-impedance state a0-a3,b0-b3=the levels of the respective nibble inputs rev. 00
in74ac257 rev. 00 maximum ratings * symbol parameter value unit v cc dc supply voltage (referenced to gnd) -0.5 to +7.0 v v in dc input voltage (referenced to gnd) -0.5 to v cc +0.5 v v out dc output voltage (referenced to gnd) -0.5 to v cc +0.5 v i in dc input current, per pin 20 ma i out dc output sink/source current, per pin 50 ma i cc dc supply current, v cc and gnd pins 50 ma p d power dissipation in still air, plastic dip+ soic package+ 750 500 mw tstg storage temperature -65 to +150 c t l lead temperature, 1 mm from case for 10 seconds (plastic dip or soic package) 260 c * maximum ratings are those values beyond which damage to the device may occur. functional operation should be restricted to the reco mmended operating conditions. +derating - plastic dip: - 10 mw/ c from 65 to 125 c soic package: : - 7 mw/ c from 65 to 125 c recommended operating conditions symbol parameter min max unit v cc dc supply voltage (referenced to gnd) 2.0 6.0 v v in , v out dc input voltage, output voltage (referenced to gnd) 0 v cc v t j junction temperature (pdip) 140 c t a operating temperature, all package types -40 +85 c i oh output current - high -24 ma i ol output current - low 24 ma t r , t f input rise and fall time * (except schmitt inputs) v cc =3.0 v v cc =4.5 v v cc =5.5 v 0 0 0 150 40 25 ns/v * v in from 30% to 70% v cc this device contains protection circuitry to guard agains t damage due to high static voltages or electric fields. however, precautions must be taken to avoid applications of any voltage highe r than maximum rated voltages to this high-impedance circuit. for proper operation, v in and v out should be constrained to the range gnd (v in or v out ) v cc . unused inputs must always be tied to an appropriate logic voltage level (e.g., either gnd or v cc ). unused outputs must be left open.
in74ac257 rev. 00 dc electrical characteristics (voltages referenced to gnd) v cc guaranteed limits symbol parameter test conditions v 25 c -40 c to 85 c unit v ih minimum high- level input voltage v out =0.1 v or v cc -0.1 v 3.0 4.5 5.5 2.1 3.15 3.85 2.1 3.15 3.85 v v il maximum low - level input voltage v out =0.1 v or v cc -0.1 v 3.0 4.5 5.5 0.9 1.35 1.65 0.9 1.35 1.65 v v oh minimum high- level output voltage i out -50 a 3.0 4.5 5.5 2.9 4.4 5.4 2.9 4.4 5.4 v * v in = v ih or v il i oh =-12 ma i oh =-24 ma i oh =-24 ma 3.0 4.5 5.5 2.56 3.86 4.86 2.46 3.76 4.76 v ol maximum low- level output voltage i out 50 a 3.0 4.5 5.5 0.1 0.1 0.1 0.1 0.1 0.1 v * v in =v ih or v il i ol =12 ma i ol =24 ma i ol =24 ma 3.0 4.5 5.5 0.36 0.36 0.36 0.44 0.44 0.44 i in maximum input leakage current v in =v cc or gnd 5.5 0.1 1.0 a i oz maximum three- state leakage current v in (oe)= v ih or v il v in =v cc or gnd v out =v cc or gnd 5.5 0.5 5.0 a i old +minimum dynamic output current v old =1.65 v max 5.5 75 ma i ohd +minimum dynamic output current v ohd =3.85 v min 5.5 -75 ma i cc maximum quiescent supply current (per package) v in =v cc or gnd 5.5 8.0 80 a * all outputs loaded; thresholds on input associated with output under test. +maximum test duration 2.0 ms, one output loaded at a time. note: i in and i cc @ 3.0 v are guaranteed to be less than or equal to the respective limit @ 5.5 v v cc
in74ac257 ac electrical characteristics (c l =50pf, input t r =t f =3.0 ns) v cc * guaranteed limits symbol parameter v 25 c -40 c to 85 c unit min max min max t plh propagation delay, nibble a or b to output y (figure 1) 3.3 5.0 1.5 1.5 8.5 6.0 1.0 1.0 9.0 7.0 ns t phl propagation delay, nibble a or b to output y (figure 1) 3.3 5.0 1.5 1.5 8.5 6.0 1.0 1.0 9.0 7.0 ns t plh propagation delay, select to output y (figure 2) 3.3 5.0 1.5 1.5 10.5 7.5 1.5 1.0 11.5 8.5 ns t phl propagation delay, select to output y (figure 2) 3.3 5.0 1.5 1.5 10.5 7.5 1.5 1.0 11.5 8.5 ns t pzh propagation delay, output enable to output y (figure 3) 3.3 5.0 1.5 1.5 9.5 7.5 1.0 1.0 10.5 8.5 ns t pzl propagation delay, output enable to output y (figure 3) 3.3 5.0 1.5 1.5 9.0 8.5 1.0 1.0 10.0 9.5 ns t phz propagation delay, output enable to output y (figure 3) 3.3 5.0 1.5 1.5 10.0 9.0 1.0 1.0 11.0 10.0 ns t plz propagation delay, output enable to output y (figure 3) 3.3 5.0 1.5 1.5 9.0 8.0 1.0 1.0 10.0 9.0 ns c in maximum input capacitance 5.0 4.5 4.5 pf typical @25 c,v cc =5.0 v c pd power dissipation capacitance 50 pf * voltage range 3.3 v is 3.3 v 0.3 v voltage range 5.0 v is 5.0 v 0.5 v figure 1. switching waveforms figure 2. switching waveforms rev. 00
in74ac257 figure 3. switching waveforms expanded logic diagram rev. 00
in74ac257 n suffix plastic dip (ms - 001bb) symbol min max a 18.67 19.69 b 6.1 7.11 c 5.33 d 0.36 0.56 f 1.14 1.78 g h j 0 10 k 2.92 3.81 notes: l 7.62 8.26 1. dimensions ?a?, ?b? do not include mold flash or protrusions. m 0.2 0.36 maximum mold flas h or protrus ions 0.25 mm (0.010) per s ide. n 0.38 d suffix soic (ms - 012ac) symbol min max a 9.8 10 b 3.8 4 c 1.35 1.75 d 0.33 0.51 f 0.4 1.27 g h j 0 8 notes: k 0.1 0.25 1. dimensions a and b do not include mold flash or protrusion. m 0.19 0.25 2. maximum mold flas h or protrus ion 0.15 mm (0.006) per s ide p 5.8 6.2 for a; for b ? 0.25 mm (0.010) per s ide. r 0.25 0.5 5.72 2.54 7.62 1.27 dimens ion, mm dimens ion, mm a b h c k c m j f m p g d r x 45 seating plane 0.25 (0.010) m t -t- 1 16 8 9 l h m j a b f g d seating plane n k 0.25 (0.010) m t -t- c 1 16 8 9 rev. 00
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