4-97 fast and ls ttl data carry lookahead generator the mc54/74f182 is a high-speed carry lookahead generator . it is general - ly used with the f181, f381 or 29f01 4-bit arithmetic logic unit to provide high- speed lookahead over word lengths of more than four bits. ? provides lookahead carries across a group of four alus ? multi-level lookahead high-speed arithmetic operation over long word lengths c n + x connection diagram dip (top view) 15 16 14 13 12 11 10 2 1 3 4 5 6 7 v cc 9 8 p 2 g 2 c n c n + y g c n + z g 1 p 1 g 0 p 0 g 3 p 3 p gnd logic diagram c n + x g 3 g p 3 g 2 p 2 g 1 p 1 g 0 p 0 c n c n + y c n + z p mc54fxxxj ceramic mc74fxxxn plastic mc74fxxxd soic mc54/74f182 carry lookahead generator fast ? schottky ttl j suffix ceramic case 620-09 n suffix plastic case 648-08 16 1 16 1 ordering information 16 1 d suffix soic case 751b-03 logic symbol 13 4 3 2 1 15 14 6 5 7 10 9 11 12 c n p 0 g 0 p 1 g 1 p 2 g 2 p 3 g 3 p g c n + x c n + y c n + z v cc = pin 16 gnd = pin 8
4-98 fast and ls ttl data mc54/74f182 function table inputs outputs c n g 0 p 0 g 1 p 1 g 2 p 2 g 3 p 3 c n+x c n+y c n+z g p x h h l l h x l x l x h h x l h x x x h h l x h h h x l l h x h x l x x x l x h x l x x l h h x l x l h x x x x x h h l x x x h h h x l x h h h x h x l l h x h x h x l x x x x x l x h x x x l x x l h x l x x l x l h h x l x l x l h x x x x x h h h x x x h h h x h x h h h x h x h h h x h x h x h x x x x x l x l x x x l x x l l x l x x l x l l l x l x l x l l h x x x h x h x x h x x h x h x x x h h l l l l l h = high voltage level l = low voltage level x = don't care guaranteed operating ranges symbol parameter min typ max unit v cc supply voltage 54,74 4.5 5.0 5.5 v t a operating ambient temperature range 54 55 25 125 c a 74 0 25 70 i oh output current e high 54, 74 1.0 ma i ol output current e low 54, 74 20 ma
4-99 fast and ls ttl data mc54/74f182 dc characteristics over operating temperature range (unless otherwise specified) limits symbol parameter min typ max unit test conditions v ih input high voltage 2.0 v guaranteed input high voltage v il input low voltage 0.8 v guaranteed input low voltage v ik input clamp diode voltage 1.2 v i in = 18 ma v cc = min v oh output high voltage 54, 74 2.5 3.4 v i oh = 1.0 ma v cc = 4.50 v 74 2.7 3.4 v i oh = 1.0 ma v cc = 4.75 v v ol output low voltage 0.35 0.5 v i ol = 20 ma v cc = min i ih input high current 20 m a v in = 2.7 v v cc = max 100 m a v in = 7.0 v v cc = max c n input 1.2 p 3 input 2.4 i il input low p 2 input 3.6 ma v in = 0.5 v v cc = max current g 3 , p 0 , p 1 inputs 4.8 g 0 , g 2 inputs 8.4 g 1 input 9.6 i os output short circuit current (note 2) 60 150 ma v out = 0 v v cc = max i cch power supply current (all outputs high) 18.4 28 ma p 3 , g 3 = 4.5 v all other inputs = gnd v cc = max i ccl power supply current (all outputs low) 23.5 36 ma g 0 , g 1 , g 2 = 4.5 v all other inputs = gnd v cc = max notes: 1. for conditions shown as min or max, use the appropriate value specified under guaranteed operating ranges. 2. no more than one output should be shorted at a time, nor for more than 1 second. ac characteristics 54/74f 54f 74f t a = +25 c t a = 55 c to +125 c t a = 0 c to +70 c v cc = +5.0 v v cc = 5.0 v 10% v cc = 5.0v 10% c l = 50 pf c l = 50 pf c l = 50 pf symbol parameter min typ max min max min max unit t plh propagation delay 3.0 6.6 8.5 3.0 10.5 3.0 9.5 ns t phl c n to c n + x , c n + y , c n + z 3.0 6.8 9.0 3.0 11 3.0 10 ns t plh propagation delay 2.5 6.2 8.0 2.5 10.7 2.5 9.0 ns t phl p 0 , p 1 , or p 2 to c n + x , c n + y , c n + z 1.5 3.7 5.0 1.5 6.5 1.5 6.0 ns t plh propagation delay 2.5 6.5 8.5 2.5 10.5 2.5 9.5 ns t phl g 0 , g 1 , or g 2 to c n + x , c n + y , c n + z 1.5 3.9 5.2 1.5 6.5 1.5 6.0 ns
4-100 fast and ls ttl data mc54/74f182 ac characteristics (continued) 54/74f 54f 74f t a = +25 c t a = 55 c to +125 c t a = 0 c to +70 c v cc = +5.0 v v cc = 5.0 v 10% v cc = 5.0v 10% c l = 50 pf c l = 50 pf c l = 50 pf symbol parameter min typ max min max min max unit t plh propagation delay 2.0 7.9 10 2.0 12.5 2.0 11 ns t phl p 1 , p 2 , or p 3 to g 2.0 6.0 8.0 2.0 9.5 2.0 9.0 ns t plh propagation delay 2.0 8.3 10.5 2.0 12.5 2.0 11.5 ns t phl g n to g 1.5 5.7 7.5 1.5 9.5 1.5 8.5 ns t plh propagation delay 2.5 5.7 7.5 2.5 11 2.5 8.5 ns t phl p n to p 2.5 4.1 5.5 2.5 7.5 2.5 6.5 ns functional description the f182 carry lookahead generator accepts up to four pairs of active-low carry propagate (p 0 -p 3 ) and carry gen - erate (g 0 -g 3 ) signals and an active-high carry input (c n ) and provides anticipated active-high carries (c n + x , c n + y , c n + z ) across four groups of binary adders. the f182 also has ac - tive-low carry propagate (p ) and carry generate (g ) out- puts which may be used for further levels of lookahead. the logic equations provided at the output are: c n + x = g 0 + p 0 c n c n + y = g 1 + p 1 g 0 + p 1 p 0 c n c n + z = g 2 + p 2 g 1 + p 2 p 1 g 0 + p 2 p 1 p 0 c n g = g 3 + p 3 g 2 + p 3 p 2 g 1 + p 3 p 2 p 1 g 0 p = p 3 p 2 p 1 p 0 also, the f182 can be used with binary alus in an active- low or active-high input operand mode. the connections (figure 1) to and from the alu to the carry lookahead genera - tor are identical in both cases. carries are rippled between lookahead blocks. the critical speed path follows the circled numbers. there are several possible arrangements for the carry interconnects, but all achieve about the same speed. a 28-bit alu is formed by dropping the last f181 or f381. 5 3 2 1 figure 1. 32-bit alu with ripple carry between 16-bit lookahead alus cn alu** g p cn alu** g p cn alu** g p cn alu** g p a , b c n c n + 4 alu** g p c n c n + 4 alu** g p c n c n + 4 alu** c n c n + 4 alu** c out (c 32) f c in p 0 g 0 p 1 g 1 p 2 g 2 p 3 g 3 g p c n c n + x c n + y c n + z f182 p 0 g 0 p 1 g 1 p 2 g 2 p 3 g 3 g p c n c n + x c n + y c n + z f182 c 16 ** alus may be either f181, f381, or 2901a. 6 4
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