4-247 fast and ls ttl data octal bidirectional transceiver with 8-bit parity generator checker (3-state outputs) the mc74f657a and mc74f657b are octal bidirectional t ransceivers with an 8-bit parity generator/checker and 3-state outputs. the a and b options are faster versions of the f657 and contain eight non- inverting buf fers with 3-state outputs and an 8-bit parity generator/checker . these devices are intended for bus-oriented applications. the buf fers have a guaranteed current sinking capability of 24 ma at the a ports and 64 ma at the b ports. the t ransmit/receiver (t/r ) input determines the direction of the data flow through the bidirectional transceivers. t ransmit (active high) en - ables data from a ports to b ports; receive (active low) enables data from b ports to a ports. ? high-impedance npn base input for reduced loading (20 m a in high and low states) ? ideal in applications where high output drive and light bus loading are required (i il is 20 m a versus fast std of 600 m a) ? combines f245 and f280a functions in one package ? 3-state outputs ? b outputs, parity, error , sink 64 ma and source 15 ma ? 15 ma source current ? input diodes for termination effects ? glitchless outputs during power up and power down ? high impedance outputs during power off ? esd protection > 4000 volts pin assignment 22 21 20 19 18 17 1 2 3 4 5 6 7 24 23 8 oe t/r b 0 b 1 b 2 b 3 gnd gnd b 4 a 0 a 1 a 2 a 3 a 4 v cc a 5 9 10 11 12 a 6 a 7 error 16 15 14 13 b 5 b 7 b 6 parity odd/ even logic symbol oe even /odd parity t/r b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7 24 11 1 23 22 21 20 17 16 15 14 13 error 12 a 0 a 1 a 2 a 3 a 4 a 5 a 6 a 7 2 3 4 5 6 8 9 10 mc74f657a,b octal bidirectional transceiver with 8-bit parity generator checker (3-state outputs) fast ? schottky ttl ordering information mc74fxxxaj/bj ceramic mc74fxxxan/bn plastic mc74fxxxadw/bdw soic n suffix plastic case 724-03 dw suffix soic case 751e-03 24 1 24 1 j suffix ceramic case 758-01 24 1
4-248 fast and ls ttl data mc74f657a, b guaranteed operating ranges symbol parameter min typ max unit v cc supply voltage 74 4.5 5.0 5.5 v t a operating ambient temperature range 74 0 25 70 c i oh output current e high 74 3.0/15 ma i ol output current e low 74 24/64 ma function table number of inputs that are high inputs input/output outputs oe t/r even /odd parity error outputs mode l h h h z transmit l h l l z transmit l l h h h receive 0, 2, 4, 6, 8 l l h l l receive l l l h l receive l l l l h receive number of inputs that are high inputs input/output outputs oe t/r even /odd parity error outputs mode l h h l z transmit l h l h z transmit l l h h l receive 1, 3, 5, 7 l l h l h receive l l l h h receive l l l l l receive don't care h x x z z z h = high v oltage level; l = low v oltage level; x = don't care; z = high impedance state.
4-249 fast and ls ttl data mc74f657a, b 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 0.73 1.2 v v cc = min, i in = 18 ma output high voltage all outputs 74 2.4 v i oh = 3.0 ma v cc = 4.5 v v oh output high voltage 2.7 3.4 v i oh = 3.0 ma v cc = 4.75 v output high voltage b0b7 parity, error 74 2.0 v i oh = 15 ma v cc = 4.5 v output low voltage a0a7 74 0.35 0.5 v i ol = 24 ma v cc = min v ol output low voltage b0b7 parity, error 74 0.4 0.55 v i ol = 64 ma v cc = min i ih input high current t/r , oe , even /odd 100 m a v cc = 0 v, v in = 7.0 v i ih input high current a0a7 2.0 ma v cc = 5.5 v, v in = 5.5 v i ih input high current b0b7, parity 1.0 ma v cc = 5.5 v, v in = 5.5 v ih even /odd 20 m a v cc = max, v in = 2.7 v t/r , oe 40 m a v cc = max, v in = 2.7 v i il input low current even /odd 20 m a v cc = max, v in = 0.5 v i il input low current t/r , oe 40 m a v cc = max, v in = 0.5 v i ih + i ozh off-state current high level voltage applied a0a7 b0b7 parity 70 m a v cc = max, v out = 2.7 v i il +i ozl off-state current low level voltage applied b0b7 parity 70 m a v cc = max, v out = 0.5 v i ozh off-state output current, high-level voltage applied 50 m a v cc = max, v out = 2.7 v i ozl off-state output current, low-level voltage applied error 50 m a v cc = max, v out = 0.5 v i os output short circuit current (note 2) a n outputs 60 150 ma v cc = max, v out = 0 v i os output short circuit current (note 2) parity, b n outputs, error 100 225 ma v cc = max, v out = 0 v i cc total supply current i cch 90 135 ma v cc = max i cc total supply current i ccl 106 150 ma v cc = max cc i ccz 98 145 cc = max notes: 1. for conditions shown as min or max, use appropriate value specified under recommended operating conditions for the applicable device type. 2. not more than one output should be shorted at one time, nor for more than 1 second.
4-250 fast and ls ttl data mc74f657a, b f657a ac electrical characteristics symbol parameter 74f 74f unit symbol parameter t a = +25 c v cc = +5.0 v c l = 50 pf t a = 0 c to +70 c v cc = +5.0 v 10% c l = 50 pf unit symbol parameter min typ max min max unit t plh t phl propagation delay 2.0 7.0 2.0 7.5 ns plh t phl a n to b n or b n to a n 2.0 7.0 2.0 7.5 ns t plh propagation delay 6.0 13 5.5 14 ns t phl a n to parity 6.5 13 6.5 14 ns t plh propagation delay 4.5 10.5 4.5 11 ns t phl even /odd to parity, error 4.5 10.5 4.5 11.5 ns t plh propagation delay 7.0 18 6.5 19 ns t phl b n to error 7.0 18 6.5 19 ns t plh propagation delay 8.0 14 7.0 15 ns t phl parity to error 7.0 14 7.0 15 ns t pzh output enable time 3.0 8.0 3.0 9.0 ns t pzl to high or low level 4.0 9.0 4.0 10 ns t phz t plz output disable time 2.0 7.5 2.0 8.0 ns phz t plz from high or low level 2.0 6.0 2.0 6.5 ns f657b ac electrical characteristics symbol parameter 74f 74f unit symbol parameter t a = +25 c v cc = +5.0 v c l = 50 pf t a = 0 c to +70 c v cc = +5.0 v 10% c l = 50 pf unit symbol parameter min typ max min max unit t plh propagation delay 2.0 6.0 2.0 6.5 ns t phl a n to b n or b n to a n 2.0 6.0 2.0 6.5 ns t plh propagation delay 4.5 11.5 4.5 13 ns t phl a n to parity 4.5 11.5 4.5 13 ns t plh propagation delay 2.0 7.5 2.0 8.5 ns t phl even /odd to parity, error 2.0 7.5 2.0 8.5 ns t plh propagation delay 4.0 15 3.5 16 ns t phl b n to error 4.0 15 3.5 16 ns t plh propagation delay 5.0 11 4.0 12 ns t phl parity to error 5.0 11 4.0 12 ns t pzh output enable time 2.0 7.0 2.0 8.0 ns t pzl to high or low level 2.0 7.0 2.0 8.0 ns t phz t plz output disable time 2.0 6.0 2.0 6.5 ns phz t plz from high or low level 2.0 6.0 2.0 6.5 ns
4-251 fast and ls ttl data mc74f657a, b logic diagram t/r oe a 0 a 1 a 2 a 3 a 4 a 5 a 6 a 7 b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7 even /odd parity error
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