Version 4
SHEET 1 1380 1212
WIRE -384 -96 -448 -96
WIRE 448 -96 384 -96
WIRE -448 -64 -448 -96
WIRE 384 -64 384 -96
WIRE -448 48 -448 16
WIRE 384 48 384 16
WIRE 176 176 176 160
WIRE 352 224 240 224
WIRE 176 272 176 256
WIRE 240 272 240 224
WIRE 240 272 176 272
WIRE 256 272 240 272
WIRE 352 272 320 272
WIRE 640 320 576 320
WIRE 352 336 -464 336
WIRE 352 368 -96 368
WIRE 640 384 576 384
WIRE 352 448 336 448
WIRE -96 464 -96 368
WIRE -464 544 -464 336
WIRE -96 576 -96 544
WIRE -464 656 -464 624
FLAG 384 48 0
FLAG -96 576 0
FLAG -96 368 trig_b
FLAG 640 320 out_q
FLAG -464 656 0
FLAG -464 336 trig_a
FLAG -448 48 0
FLAG -384 -96 _reset
FLAG 640 384 _out_q
FLAG 176 160 vcc
FLAG 336 448 _reset
FLAG 448 -96 VCC
SYMBOL voltage 384 -80 R0
SYMATTR InstName V1
SYMATTR Value {VCC}
SYMBOL voltage -96 448 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PWL(0,{VCC},60u,{VCC},60.1u,0, 65u,0,65.1u,{VCC},150u,{VCC},150.1u,0,155u,0,155.1u,{VCC})
SYMBOL voltage -464 528 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V3
SYMATTR Value PWL(0,0,30u,0,30.1u,{VCC}, 35u,{VCC},35.1u,0,100u,0,100.1u,{VCC},105u,{VCC},105.1u,0,110u,0,110.1u,{VCC},120u,{VCC},120.1u,0)
SYMBOL voltage -448 -80 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V4
SYMATTR Value PWL(0,{VCC},160u,{VCC},160.1u,0, 165u,0,165.1u,{VCC})
SYMBOL res 160 160 R0
SYMATTR InstName R2
SYMATTR Value 20k
SYMBOL cap 256 288 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName C3
SYMATTR Value 1n
SYMBOL 74HC4538 464 160 R0
SYMATTR InstName U1
SYMATTR SpiceLine VCC={VCC}  SPEED=1 TRIPDT=1e-9
TEXT -440 -296 Left 0 !.tran 0 200u 5n
TEXT -440 -424 Left 0 ;Libraries
TEXT -440 -320 Left 0 ;Simulation
TEXT -96 -560 Left 0 ;Right click with the mouse on the symbol to see the properties.\n \nSpiceModel:   VCC 0                    \nSpecLine:       VCC=5  SPEED=1 TRIPDT=1e-9     \n \nDescription:\nVCC 0      +supply net is VDD, - supply net is 0(GND)\nVCC=5 is the value of supply voltage\nSPEED=1   delay multiplier\nTRIPDTV=1e-9   internal timestep for A elements
TEXT -448 -232 Left 0 !.param VCC=5
TEXT -192 -232 Left 0 ;----> Take a look how the voltage VCC and its value is passed to all subcircuits.\n       SpicecLine:   VCC={VCC}  SPEED=1 TRIPDT=1e-9
TEXT -424 -824 Left 0 ;Test circuit for the 74HC4538\n \nTest cases: \n1. Single trigger on A\n2. Single trigger on B\n3. Double (re-)trigger on A\n4. Trigger on B but output pulse early terminated by reset input
TEXT -440 -392 Left 0 !.include 74hc.lib
TEXT 240 136 Left 0 ;T=0.7*R*C