* SPICE netlist
V1 N004 0 PULSE(0 3.8 10m 1m 1m 10 20)
V2 N013 0 PULSE(0 3.8 20m 1m 1m 10 20)
V3 N018 0 PULSE(0 2.8 27m 1m 1m 10 20)
MQ3 N002 N007 N003 N003 Si2316DS
R1 N002 N001 50m
C1 N007 0 .47
R2 N012 N020 4.7K
C2 N023 0 .22
R3 N011 N017 86.6K
R4 N017 0 49.9K
R5 N009 N016 178K
R6 N016 0 49.9K
R7 N001 N006 100
R8 N009 N014 100
R9 N011 N019 100
C3 N001 0 10
C4 N001 N008 .01
C5 N009 N015 .01
C6 N009 0 10
C7 N011 0 10
C8 N011 N021 .01
XU1 N009 N014 0 N015 N013 MP_01 MP_02 N013 LT1763-2.5 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
MQ4 N016 N022 0 0 BSS123
V4 N022 0 PULSE(0 5 2.5 100n 100n 200u 100)
Rload1 N012 0 70
C9 N003 0 10
C10 N010 0 10
C11 N012 0 10
V5 N005 0 PULSE(0 1 2 100n 100n 100u 100)
S1 0 N003 N005 0 SSHRT
XU2 N016 N017 N017 N017 N019 N012 N014 N010 N006 N003 0 N020 N007 N002 N001 N023 LTC2921-3.3 ;pnba V1)V2)V3)V4)S3)D3)S2)D2)S1)D1)Gnd)PG)Gate)Sense)Vcc)Timer
XU3 N001 N006 0 N008 N004 MP_03 MP_04 N004 LT1763-3.3 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
XU4 N011 N019 0 N021 N018 MP_05 MP_06 N018 LT1763-1.5 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
Rload2 N010 0 70
Rload3 N003 0 70
MQ1 N009 N007 N010 N010 Si2316DS
MQ2 N011 N007 N012 N012 Si2316DS
.tran 4

* LTspice schematic (.asc)
Version 4
SHEET 1 2944 1280
WIRE -704 -624 -864 -624
WIRE -352 -624 -704 -624
WIRE -240 -624 -352 -624
WIRE 176 -624 -240 -624
WIRE 208 -624 176 -624
WIRE 304 -624 288 -624
WIRE 464 -624 304 -624
WIRE 800 -624 560 -624
WIRE 960 -624 800 -624
WIRE 1088 -624 960 -624
WIRE 1312 -624 1088 -624
WIRE -1424 -608 -1472 -608
WIRE -1184 -608 -1344 -608
WIRE -1152 -608 -1184 -608
WIRE -240 -608 -240 -624
WIRE 960 -608 960 -624
WIRE 1088 -608 1088 -624
WIRE 1312 -608 1312 -624
WIRE -352 -592 -352 -624
WIRE 1472 -592 1360 -592
WIRE 1472 -576 1472 -592
WIRE -640 -560 -864 -560
WIRE 544 -544 544 -576
WIRE 544 -544 448 -544
WIRE 1376 -544 1360 -544
WIRE -240 -528 -240 -544
WIRE -1184 -512 -1184 -608
WIRE -1152 -512 -1184 -512
WIRE 960 -512 960 -544
WIRE 1088 -512 1088 -528
WIRE -816 -496 -864 -496
WIRE -704 -496 -704 -624
WIRE -704 -496 -752 -496
WIRE -640 -496 -640 -560
WIRE -352 -496 -352 -512
WIRE -352 -496 -640 -496
WIRE 1312 -496 1312 -528
WIRE 1472 -480 1472 -496
WIRE -512 -464 -560 -464
WIRE -256 -464 -512 -464
WIRE 464 -464 -256 -464
WIRE 848 -464 560 -464
WIRE 960 -464 848 -464
WIRE 1088 -464 960 -464
WIRE 960 -448 960 -464
WIRE 1088 -448 1088 -464
WIRE -512 -432 -512 -464
WIRE -1008 -416 -1008 -448
WIRE 448 -384 448 -544
WIRE 544 -384 544 -416
WIRE 544 -384 448 -384
WIRE -512 -352 -512 -368
WIRE 960 -352 960 -384
WIRE 1088 -352 1088 -368
WIRE -416 -304 -480 -304
WIRE -80 -304 -416 -304
WIRE 464 -304 -80 -304
WIRE 704 -304 560 -304
WIRE 896 -304 704 -304
WIRE 960 -304 896 -304
WIRE 1088 -304 960 -304
WIRE 960 -288 960 -304
WIRE 1088 -288 1088 -304
WIRE -416 -272 -416 -304
WIRE -704 -256 -864 -256
WIRE -560 -256 -560 -464
WIRE -560 -256 -704 -256
WIRE -256 -256 -256 -464
WIRE -80 -256 -80 -304
WIRE -1424 -240 -1472 -240
WIRE -1184 -240 -1344 -240
WIRE -1152 -240 -1184 -240
WIRE -560 -224 -560 -256
WIRE 448 -224 448 -384
WIRE 544 -224 544 -256
WIRE 544 -224 448 -224
WIRE -640 -192 -864 -192
WIRE -416 -192 -416 -208
WIRE 960 -192 960 -224
WIRE 1088 -192 1088 -208
WIRE 176 -160 176 -624
WIRE 304 -160 304 -624
WIRE -1184 -144 -1184 -240
WIRE -1152 -144 -1184 -144
WIRE -816 -128 -864 -128
WIRE -704 -128 -704 -256
WIRE -704 -128 -752 -128
WIRE -640 -128 -640 -192
WIRE -560 -128 -560 -144
WIRE -560 -128 -640 -128
WIRE 704 -128 704 -304
WIRE -256 -64 -256 -176
WIRE -144 -64 -256 -64
WIRE 96 -64 -144 -64
WIRE 448 -64 448 -224
WIRE 448 -64 384 -64
WIRE -1008 -48 -1008 -80
WIRE 448 -32 448 -64
WIRE -80 16 -80 -176
WIRE 32 16 -80 16
WIRE 96 16 32 16
WIRE -256 32 -256 -64
WIRE -80 32 -80 16
WIRE 448 48 448 32
WIRE -704 96 -864 96
WIRE -480 96 -480 -304
WIRE -480 96 -704 96
WIRE 32 96 32 16
WIRE 96 96 32 96
WIRE -1424 112 -1472 112
WIRE -1184 112 -1344 112
WIRE -1152 112 -1184 112
WIRE -480 112 -480 96
WIRE -256 144 -256 112
WIRE -80 144 -80 112
WIRE -640 160 -864 160
WIRE 32 176 32 96
WIRE 96 176 32 176
WIRE 704 176 704 -48
WIRE 704 176 384 176
WIRE -1184 208 -1184 112
WIRE -1152 208 -1184 208
WIRE -816 224 -864 224
WIRE -704 224 -704 96
WIRE -704 224 -752 224
WIRE -640 224 -640 160
WIRE -480 224 -480 192
WIRE -480 224 -640 224
WIRE -352 256 -352 -496
WIRE 96 256 -352 256
WIRE 800 256 800 -624
WIRE 800 256 384 256
WIRE -1008 304 -1008 272
WIRE -560 336 -560 -128
WIRE 96 336 -560 336
WIRE 848 336 848 -464
WIRE 848 336 384 336
WIRE -480 416 -480 224
WIRE 96 416 -480 416
WIRE 896 416 896 -304
WIRE 896 416 384 416
WIRE -144 448 -144 -64
WIRE -192 528 -608 528
WIRE 304 528 304 512
WIRE -608 544 -608 528
WIRE -144 560 -144 544
WIRE 176 560 176 512
WIRE 304 608 304 592
WIRE -608 640 -608 624
FLAG 1088 -512 0
FLAG 1312 -496 0
FLAG 1472 -480 0
FLAG 1376 -544 0
FLAG -1472 -240 0
FLAG -1472 112 0
FLAG 1088 -352 0
FLAG 1088 -192 0
FLAG -1472 -608 0
FLAG 448 48 0
FLAG 304 608 0
FLAG 176 560 0
FLAG -80 144 0
FLAG -256 144 0
FLAG -240 -528 0
FLAG -1008 -416 0
FLAG -1008 -48 0
FLAG -512 -352 0
FLAG -416 -192 0
FLAG -1008 304 0
FLAG -144 560 0
FLAG -608 640 0
FLAG 960 -512 0
FLAG 960 -352 0
FLAG 960 -192 0
SYMBOL voltage -1328 -608 R90
SYMATTR InstName V1
SYMATTR Value PULSE(0 3.8 10m 1m 1m 10 20)
SYMBOL voltage -1328 -240 R90
SYMATTR InstName V2
SYMATTR Value PULSE(0 3.8 20m 1m 1m 10 20)
SYMBOL voltage -1328 112 R90
SYMATTR InstName V3
SYMATTR Value PULSE(0 2.8 27m 1m 1m 10 20)
SYMBOL nmos 464 -576 R270
SYMATTR InstName Q3
SYMATTR Value Si2316DS
SYMBOL res 304 -640 R90
SYMATTR InstName R1
SYMATTR Value 50m
SYMBOL cap 432 -32 R0
SYMATTR InstName C1
SYMATTR Value .47
SYMBOL res 688 -144 R0
SYMATTR InstName R2
SYMATTR Value 4.7K
SYMBOL cap 288 528 R0
SYMATTR InstName C2
SYMATTR Value .22
SYMBOL res -96 -272 R0
SYMATTR InstName R3
SYMATTR Value 86.6K
SYMBOL res -96 16 R0
SYMATTR InstName R4
SYMATTR Value 49.9K
SYMBOL res -272 -272 R0
SYMATTR InstName R5
SYMATTR Value 178K
SYMBOL res -272 16 R0
SYMATTR InstName R6
SYMATTR Value 49.9K
SYMBOL res -368 -608 R0
SYMATTR InstName R7
SYMATTR Value 100
SYMBOL res -576 -240 R0
SYMATTR InstName R8
SYMATTR Value 100
SYMBOL res -496 96 R0
SYMATTR InstName R9
SYMATTR Value 100
SYMBOL cap -256 -608 R0
SYMATTR InstName C3
SYMATTR Value 10
SYMBOL cap -752 -512 R90
SYMATTR InstName C4
SYMATTR Value .01
SYMBOL cap -752 -144 R90
SYMATTR InstName C5
SYMATTR Value .01
SYMBOL cap -528 -432 R0
SYMATTR InstName C6
SYMATTR Value 10
SYMBOL cap -432 -272 R0
SYMATTR InstName C7
SYMATTR Value 10
SYMBOL cap -752 208 R90
SYMATTR InstName C8
SYMATTR Value .01
SYMBOL PowerProducts\\LT1763-2.5 -1008 -192 R0
SYMATTR InstName U1
SYMBOL nmos -192 448 R0
SYMATTR InstName Q4
SYMATTR Value BSS123
SYMBOL voltage -608 528 R0
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 2.5 100n 100n 200u 100)
SYMBOL res 1072 -304 R0
SYMATTR InstName Rload1
SYMATTR Value 70
SYMBOL cap 944 -608 R0
SYMATTR InstName C9
SYMATTR Value 10
SYMBOL cap 944 -448 R0
SYMATTR InstName C10
SYMATTR Value 10
SYMBOL cap 944 -288 R0
SYMATTR InstName C11
SYMATTR Value 10
SYMBOL voltage 1472 -592 R0
SYMATTR InstName V5
SYMATTR Value PULSE(0 1 2 100n 100n 100u 100)
SYMBOL sw 1312 -512 R180
SYMATTR InstName S1
SYMATTR Value SSHRT
SYMBOL LTC2921-3.3 240 176 R0
SYMATTR InstName U2
SYMBOL PowerProducts\\LT1763-3.3 -1008 -560 R0
SYMATTR InstName U3
SYMBOL PowerProducts\\LT1763-1.5 -1008 160 R0
SYMATTR InstName U4
SYMBOL res 1072 -464 R0
SYMATTR InstName Rload2
SYMATTR Value 70
SYMBOL res 1072 -624 R0
SYMATTR InstName Rload3
SYMATTR Value 70
SYMBOL nmos 464 -416 R270
SYMATTR InstName Q1
SYMATTR Value Si2316DS
SYMBOL nmos 464 -256 R270
SYMATTR InstName Q2
SYMATTR Value Si2316DS