* SPICE netlist
V1 N004 0 PULSE(0 2.8 10m 1m 1m 10 20)
V2 N013 0 PULSE(0 2.5 20m 1m 1m 10 20)
V3 N018 0 PULSE(0 2.5 27m 1m 1m 10 20)
MQ1 N002 N007 N003 N003 Si2316DS
R1 N002 N001 50m
C1 N007 0 .47
R2 N012 _RESET 4.7K
C2 N022 0 .22
R3 N011 N017 86.6K
R4 N017 0 49.9K
R5 N009 N016 113K
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 N020 .01
MQ2 N016 N021 0 0 BSS123
V4 N021 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
XU1 N016 N017 N017 N017 N019 N012 N014 N010 N006 N003 0 _RESET N007 N002 N001 N022 LTC2921-2.5 ;pnba V1)V2)V3)V4)S3)D3)S2)D2)S1)D1)Gnd)PG)Gate)Sense)Vcc)Timer
XU2 N001 N006 0 N008 N004 MP_01 MP_02 N004 LT1763-2.5 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
XU3 N009 N014 0 N015 N013 MP_03 MP_04 N013 LT1763-1.8 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
XU4 N011 N019 0 N020 N018 MP_05 MP_06 N018 LT1763-1.5 ;pnba OUT)Sense)GND)BYP)_SHDN)))IN
MQ3 N009 N007 N010 N010 Si2316DS
MQ4 N011 N007 N012 N012 Si2316DS
Rload2 N010 0 70
Rload3 N003 0 70
.tran 4

* LTspice schematic (.asc)
Version 4
SHEET 1 2912 1280
WIRE -688 -624 -848 -624
WIRE -336 -624 -688 -624
WIRE -224 -624 -336 -624
WIRE 240 -624 -224 -624
WIRE 272 -624 240 -624
WIRE 368 -624 352 -624
WIRE 528 -624 368 -624
WIRE 896 -624 624 -624
WIRE 1056 -624 896 -624
WIRE 1152 -624 1056 -624
WIRE 1296 -624 1152 -624
WIRE -1408 -608 -1456 -608
WIRE -1168 -608 -1328 -608
WIRE -1136 -608 -1168 -608
WIRE -224 -608 -224 -624
WIRE 1056 -608 1056 -624
WIRE 1152 -608 1152 -624
WIRE 1296 -608 1296 -624
WIRE -336 -592 -336 -624
WIRE 1456 -592 1344 -592
WIRE 1456 -576 1456 -592
WIRE -624 -560 -848 -560
WIRE 608 -544 608 -576
WIRE 608 -544 512 -544
WIRE 1360 -544 1344 -544
WIRE -224 -528 -224 -544
WIRE -1168 -512 -1168 -608
WIRE -1136 -512 -1168 -512
WIRE 1056 -512 1056 -544
WIRE 1152 -512 1152 -528
WIRE 1296 -512 1296 -528
WIRE -800 -496 -848 -496
WIRE -688 -496 -688 -624
WIRE -688 -496 -736 -496
WIRE -624 -496 -624 -560
WIRE -336 -496 -336 -512
WIRE -336 -496 -624 -496
WIRE 1456 -480 1456 -496
WIRE -496 -464 -544 -464
WIRE -240 -464 -496 -464
WIRE 528 -464 -240 -464
WIRE 944 -464 624 -464
WIRE 1056 -464 944 -464
WIRE 1152 -464 1056 -464
WIRE 1056 -448 1056 -464
WIRE 1152 -448 1152 -464
WIRE -496 -432 -496 -464
WIRE -992 -416 -992 -448
WIRE 512 -384 512 -544
WIRE 608 -384 608 -416
WIRE 608 -384 512 -384
WIRE -496 -352 -496 -368
WIRE 1056 -352 1056 -384
WIRE 1152 -352 1152 -368
WIRE -400 -304 -464 -304
WIRE -16 -304 -400 -304
WIRE 528 -304 -16 -304
WIRE 784 -304 624 -304
WIRE 992 -304 784 -304
WIRE 1056 -304 992 -304
WIRE 1152 -304 1056 -304
WIRE 1056 -288 1056 -304
WIRE 1152 -288 1152 -304
WIRE -400 -272 -400 -304
WIRE -688 -256 -848 -256
WIRE -544 -256 -544 -464
WIRE -544 -256 -688 -256
WIRE -240 -256 -240 -464
WIRE -16 -256 -16 -304
WIRE -1408 -240 -1456 -240
WIRE -1168 -240 -1328 -240
WIRE -1136 -240 -1168 -240
WIRE -544 -224 -544 -256
WIRE 512 -224 512 -384
WIRE 608 -224 608 -256
WIRE 608 -224 512 -224
WIRE -624 -192 -848 -192
WIRE -400 -192 -400 -208
WIRE 1056 -192 1056 -224
WIRE 1152 -192 1152 -208
WIRE 240 -160 240 -624
WIRE 368 -160 368 -624
WIRE -1168 -144 -1168 -240
WIRE -1136 -144 -1168 -144
WIRE -800 -128 -848 -128
WIRE -688 -128 -688 -256
WIRE -688 -128 -736 -128
WIRE -624 -128 -624 -192
WIRE -544 -128 -544 -144
WIRE -544 -128 -624 -128
WIRE 784 -128 784 -304
WIRE -240 -64 -240 -176
WIRE -128 -64 -240 -64
WIRE 160 -64 -128 -64
WIRE 512 -64 512 -224
WIRE 512 -64 448 -64
WIRE -992 -48 -992 -80
WIRE 512 -32 512 -64
WIRE -16 16 -16 -176
WIRE 96 16 -16 16
WIRE 160 16 96 16
WIRE -240 32 -240 -64
WIRE -16 32 -16 16
WIRE 512 48 512 32
WIRE -688 96 -848 96
WIRE -464 96 -464 -304
WIRE -464 96 -688 96
WIRE 96 96 96 16
WIRE 160 96 96 96
WIRE -1408 112 -1456 112
WIRE -1168 112 -1328 112
WIRE -1136 112 -1168 112
WIRE -464 112 -464 96
WIRE -240 144 -240 112
WIRE -16 144 -16 112
WIRE -624 160 -848 160
WIRE 96 176 96 96
WIRE 160 176 96 176
WIRE 704 176 448 176
WIRE 784 176 784 -48
WIRE 784 176 704 176
WIRE -1168 208 -1168 112
WIRE -1136 208 -1168 208
WIRE -800 224 -848 224
WIRE -688 224 -688 96
WIRE -688 224 -736 224
WIRE -624 224 -624 160
WIRE -464 224 -464 192
WIRE -464 224 -624 224
WIRE -336 256 -336 -496
WIRE 160 256 -336 256
WIRE 896 256 896 -624
WIRE 896 256 448 256
WIRE -992 304 -992 272
WIRE -544 336 -544 -128
WIRE 160 336 -544 336
WIRE 944 336 944 -464
WIRE 944 336 448 336
WIRE -464 416 -464 224
WIRE 160 416 -464 416
WIRE 992 416 992 -304
WIRE 992 416 448 416
WIRE -128 448 -128 -64
WIRE -176 528 -640 528
WIRE 240 528 240 512
WIRE 368 528 368 512
WIRE -640 544 -640 528
WIRE -128 560 -128 544
WIRE 368 608 368 592
WIRE -640 640 -640 624
FLAG 1152 -512 0
FLAG 1296 -512 0
FLAG 1456 -480 0
FLAG 1360 -544 0
FLAG -1456 -240 0
FLAG -1456 112 0
FLAG 1152 -352 0
FLAG 1152 -192 0
FLAG -1456 -608 0
FLAG 512 48 0
FLAG 368 608 0
FLAG 240 528 0
FLAG -16 144 0
FLAG -240 144 0
FLAG -224 -528 0
FLAG -992 -416 0
FLAG -992 -48 0
FLAG -496 -352 0
FLAG -400 -192 0
FLAG -992 304 0
FLAG 704 176 _RESET
FLAG -128 560 0
FLAG -640 640 0
FLAG 1056 -512 0
FLAG 1056 -352 0
FLAG 1056 -192 0
SYMBOL voltage -1312 -608 R90
SYMATTR InstName V1
SYMATTR Value PULSE(0 2.8 10m 1m 1m 10 20)
SYMBOL voltage -1312 -240 R90
SYMATTR InstName V2
SYMATTR Value PULSE(0 2.5 20m 1m 1m 10 20)
SYMBOL voltage -1312 112 R90
SYMATTR InstName V3
SYMATTR Value PULSE(0 2.5 27m 1m 1m 10 20)
SYMBOL nmos 528 -576 R270
SYMATTR InstName Q1
SYMATTR Value Si2316DS
SYMBOL res 368 -640 R90
SYMATTR InstName R1
SYMATTR Value 50m
SYMBOL cap 496 -32 R0
SYMATTR InstName C1
SYMATTR Value .47
SYMBOL res 768 -144 R0
SYMATTR InstName R2
SYMATTR Value 4.7K
SYMBOL cap 352 528 R0
SYMATTR InstName C2
SYMATTR Value .22
SYMBOL res -32 -272 R0
SYMATTR InstName R3
SYMATTR Value 86.6K
SYMBOL res -32 16 R0
SYMATTR InstName R4
SYMATTR Value 49.9K
SYMBOL res -256 -272 R0
SYMATTR InstName R5
SYMATTR Value 113K
SYMBOL res -256 16 R0
SYMATTR InstName R6
SYMATTR Value 49.9K
SYMBOL res -352 -608 R0
SYMATTR InstName R7
SYMATTR Value 100
SYMBOL res -560 -240 R0
SYMATTR InstName R8
SYMATTR Value 100
SYMBOL res -480 96 R0
SYMATTR InstName R9
SYMATTR Value 100
SYMBOL cap -240 -608 R0
SYMATTR InstName C3
SYMATTR Value 10
SYMBOL cap -736 -512 R90
SYMATTR InstName C4
SYMATTR Value .01
SYMBOL cap -736 -144 R90
SYMATTR InstName C5
SYMATTR Value .01
SYMBOL cap -512 -432 R0
SYMATTR InstName C6
SYMATTR Value 10
SYMBOL cap -416 -272 R0
SYMATTR InstName C7
SYMATTR Value 10
SYMBOL cap -736 208 R90
SYMATTR InstName C8
SYMATTR Value .01
SYMBOL nmos -176 448 R0
SYMATTR InstName Q2
SYMATTR Value BSS123
SYMBOL voltage -640 528 R0
SYMATTR InstName V4
SYMATTR Value PULSE(0 5 2.5 100n 100n 200u 100)
SYMBOL res 1136 -304 R0
SYMATTR InstName Rload1
SYMATTR Value 70
SYMBOL cap 1040 -608 R0
SYMATTR InstName C9
SYMATTR Value 10
SYMBOL cap 1040 -448 R0
SYMATTR InstName C10
SYMATTR Value 10
SYMBOL cap 1040 -288 R0
SYMATTR InstName C11
SYMATTR Value 10
SYMBOL voltage 1456 -592 R0
SYMATTR InstName V5
SYMATTR Value PULSE(0 1 2 100n 100n 100u 100)
SYMBOL sw 1296 -512 R180
SYMATTR InstName S1
SYMATTR Value SSHRT
SYMBOL LTC2921-2.5 304 176 R0
SYMATTR InstName U1
SYMBOL PowerProducts\\LT1763-2.5 -992 -560 R0
SYMATTR InstName U2
SYMBOL PowerProducts\\LT1763-1.8 -992 -192 R0
SYMATTR InstName U3
SYMBOL PowerProducts\\LT1763-1.5 -992 160 R0
SYMATTR InstName U4
SYMBOL nmos 528 -416 R270
SYMATTR InstName Q3
SYMATTR Value Si2316DS
SYMBOL nmos 528 -256 R270
SYMATTR InstName Q4
SYMATTR Value Si2316DS
SYMBOL res 1136 -464 R0
SYMATTR InstName Rload2
SYMATTR Value 70
SYMBOL res 1136 -624 R0
SYMATTR InstName Rload3
SYMATTR Value 70