De su pregunta de comentario, aquí hay algunos circuitos de lado alto y algunos de conmutación de lado bajo:
Apartirdesupreguntadeltema,ycomoyasehasugerido,aprimeravistapuedepareceratractivoutilizarunpardeMOSFETdecanalP,comosemuestraacontinuación,paracambiarentrelasbaterías.
Desafortunadamente,losdiodosdesustratoMOSFETcrearánunproblemacuandounadelasbateríascaigacercade0.7voltiosmenosquelaotra.
Cuandoesosuceda,eldiododemenorvoltajeyanotendrápolarizacióninversaylabateríademayorvoltajecomenzaráabombearcorrientealademenorvoltajecuandoseactivelademayorvoltaje.
Enelesquemaincluidoacontinuación,hemostradodiodosexternos,paramayorclaridad,yheindicadolarutaqueseguirálacorrienteconvencional,conR1querepresentalacargade10amperiosquemencionó.
Tengaencuentaque,enestecaso,Q1estácompletamenteapagadoyQ2estáensaturación.
HeincluidolalistadecircuitosdeLTspiceparaquepuedasjugarconelcircuitosiquieres.
LomismosucedesihacesuncambiodeladobajousandoNMOS.
R2eslacargade10amperios,yR1representacosasdecontrolquedebenestarENCENDIDAStodoeltiempo.
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ACTUALIZACIÓN:
AunqueparecequelosMOSFETSnofuncionarándebidoalasinteraccionesentresussustratosquepermitenquelascorrientesinversasfluyancuandoelMOSFETestáencortehaciadelante,pareceunparderelés,conmilesdemegohmsentresuscontactoscuandoellos'reabierto,podría.
Paraesefin,aquíhayuncircuitoqueparecefuncionarbastantebienenunsimulador,conunapequeñaadvertencia:durantelaconmutación,hayunacaídadecargade3microsegundosquenoafectaaloscircuitosdecontroldelcircuito,perosoloalacorrienteconmutadapesadaalacarga.
Conla"sintonización" adecuada, se puede controlar el abandono y lograr una conmutación perfecta, pero ¿por qué I debería divertirme todo? ;)
Aquí está el esquema, la trama y la lista de circuitos de LTspice para que pueda jugar / optimizar el circuito si lo desea.
Version 4
SHEET 1 2680 2660
WIRE -1568 -912 -2320 -912
WIRE -1504 -912 -1568 -912
WIRE -1120 -912 -1184 -912
WIRE -368 -912 -1120 -912
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WIRE -1568 -672 -1568 -752
WIRE -1504 -672 -1568 -672
WIRE -1392 -672 -1424 -672
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WIRE -1664 -624 -1728 -624
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WIRE -1376 48 -2080 48
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WIRE -496 48 -608 48
WIRE -1920 128 -2032 128
WIRE -1856 128 -1920 128
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WIRE -1376 128 -1664 128
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WIRE -656 128 -784 128
WIRE -2320 144 -2320 -912
WIRE -2320 144 -2416 144
WIRE -368 144 -368 -912
WIRE -272 144 -368 144
WIRE -1328 160 -1328 128
WIRE -2416 176 -2416 144
WIRE -2320 176 -2320 144
WIRE -2192 176 -2192 48
WIRE -496 176 -496 48
WIRE -368 176 -368 144
WIRE -272 176 -272 144
WIRE -1792 192 -1792 128
WIRE -944 192 -944 128
WIRE -2032 272 -2032 128
WIRE -1328 272 -1328 240
WIRE -1328 272 -1424 272
WIRE -656 272 -656 128
WIRE -2416 288 -2416 240
WIRE -2320 288 -2320 256
WIRE -2320 288 -2416 288
WIRE -2080 288 -2080 48
WIRE -1328 288 -1328 272
WIRE -1264 288 -1328 288
WIRE -608 288 -608 48
WIRE -368 288 -368 256
WIRE -272 288 -272 240
WIRE -272 288 -368 288
WIRE -1328 320 -1328 288
WIRE -2192 336 -2192 256
WIRE -2080 336 -2192 336
WIRE -1792 336 -1792 272
WIRE -1728 336 -1792 336
WIRE -1584 336 -1584 16
WIRE -1584 336 -1728 336
WIRE -1104 336 -1104 16
WIRE -1024 336 -1104 336
WIRE -944 336 -944 272
WIRE -944 336 -1024 336
WIRE -496 336 -496 256
WIRE -496 336 -608 336
WIRE -2192 384 -2192 336
WIRE -1424 384 -1424 272
WIRE -496 384 -496 336
WIRE -1792 400 -1792 336
WIRE -944 400 -944 336
WIRE -1920 416 -1920 128
WIRE -784 416 -784 128
WIRE -2320 432 -2320 288
WIRE -2256 432 -2320 432
WIRE -1328 432 -1328 384
WIRE -1264 432 -1328 432
WIRE -368 432 -368 288
WIRE -368 432 -432 432
WIRE -1328 448 -1328 432
WIRE -2320 480 -2320 432
WIRE -368 480 -368 432
WIRE -2192 544 -2192 480
WIRE -1920 544 -1920 496
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FLAG -1856 544 0V
FLAG -1616 -368 0V
FLAG -1072 -368 0V
FLAG -1728 -496 0
FLAG -1728 -800 VCC
FLAG -1264 432 VREF
FLAG -1728 336 BT1_OFF
FLAG -1024 336 BT2_OFF
FLAG -1856 128 VBT1
FLAG -864 128 VBT2
FLAG -1328 48 VBAT
FLAG -1664 -624 INIT_BT1
FLAG -1344 -336 VREF
FLAG -2192 624 0
FLAG -496 624 0
FLAG -1344 -720 VCC
FLAG -1520 -368 VCC
FLAG -1168 -368 VCC
FLAG -1264 288 VCC
FLAG -2320 592 0
FLAG -368 592 0
SYMBOL schottky -1728 144 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D3
SYMATTR Value 1N5819
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res -1344 144 R0
SYMATTR InstName R7
SYMATTR Value 2k
SYMBOL zener -1312 384 R180
WINDOW 0 -45 35 Left 2
WINDOW 3 -100 -3 Left 2
SYMATTR InstName D7
SYMATTR Value EDZV6_2B
SYMBOL res -960 176 R0
SYMATTR InstName R8
SYMATTR Value 100k
SYMBOL res -960 384 R0
SYMATTR InstName R12
SYMATTR Value 43k
SYMBOL res -1808 176 R0
SYMATTR InstName R6
SYMATTR Value 100k
SYMBOL res -1808 384 R0
SYMATTR InstName R11
SYMATTR Value 43k
SYMBOL zener -1312 512 R180
WINDOW 0 -42 30 Left 2
WINDOW 3 -117 -9 Left 2
SYMATTR InstName D8
SYMATTR Value EDZV6_2B
SYMBOL Comparators\LT1017 -1568 -368 M270
WINDOW 0 -87 -49 Left 2
WINDOW 3 -104 -83 Left 2
SYMATTR InstName U2A
SYMBOL Comparators\LT1017 -1120 -368 R270
WINDOW 0 -91 43 Left 2
WINDOW 3 -108 75 Left 2
SYMATTR InstName U2B
SYMBOL Misc\battery -1920 400 R0
WINDOW 3 24 104 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 13 96 Left 2
SYMATTR Value PULSE(24 16 5 1 1m 3 10)
SYMATTR InstName BT1
SYMBOL res -1712 -784 M0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL cap -1712 -592 M0
SYMATTR InstName C1
SYMATTR Value 100n
SYMBOL cap -1584 -512 R0
SYMATTR InstName C2
SYMATTR Value 100n
SYMBOL cap -1136 -512 R0
SYMATTR InstName C3
SYMATTR Value 100n
SYMBOL res -1408 -688 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R2
SYMATTR Value 100k
SYMBOL res -1264 -688 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R3
SYMATTR Value 100k
SYMBOL cap -1440 384 R0
WINDOW 0 -20 7 Left 2
WINDOW 3 -44 58 Left 2
SYMATTR InstName C5
SYMATTR Value 100µ
SYMBOL diode -1504 -560 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL diode -1184 -560 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL sw -2032 368 M180
SYMATTR InstName K1
SYMBOL sw -656 368 R180
SYMATTR InstName K2
SYMBOL res -1392 608 R0
SYMATTR InstName R13
SYMATTR Value 2.4
SYMBOL npn -2256 384 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL res -2208 160 R0
SYMATTR InstName R5
SYMATTR Value 1500
SYMBOL npn -432 384 M0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL res -480 160 M0
SYMATTR InstName R9
SYMATTR Value 1500
SYMBOL res -2336 160 R0
SYMATTR InstName R4
SYMATTR Value 10k
SYMBOL Misc\battery -784 400 R0
WINDOW 3 24 104 Invisible 2
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 0 12 97 Left 2
SYMATTR Value PULSE(24 16 10 1 1m 3 10)
SYMATTR InstName BT2
SYMBOL CD4023B -1648 -800 R270
WINDOW 0 29 121 VRight 2
WINDOW 3 59 95 VRight 2
SYMATTR InstName U1A
SYMATTR SpiceLine VDD=12 SPEED=1.0 TRIPDT=5e-9
SYMBOL CD4023B -1040 -800 M270
WINDOW 0 29 121 VRight 2
WINDOW 3 59 95 VRight 2
SYMATTR InstName U1B
SYMATTR SpiceLine VDD=12 SPEED=1.0 TRIPDT=5e-9
SYMBOL CD4023B -1024 624 R90
WINDOW 0 5 153 VRight 2
WINDOW 3 30 125 VRight 2
SYMATTR InstName U1C
SYMATTR SpiceLine VDD=12 SPEED=1.0 TRIPDT=5e-9
SYMBOL schottky -992 144 M270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value 1N5819
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap -2336 480 R0
SYMATTR InstName C4
SYMATTR Value 10n
SYMBOL diode -2400 240 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMATTR Value 1N4148
SYMBOL res -352 160 M0
SYMATTR InstName R10
SYMATTR Value 10k
SYMBOL cap -352 480 M0
SYMATTR InstName C6
SYMATTR Value 10n
SYMBOL diode -288 240 M180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D6
SYMATTR Value 1N4148
TEXT -2024 576 Left 2 !.tran 30 startup uic
TEXT -2024 600 Left 2 !.inc CD4000.lib
TEXT -2024 624 Left 2 !.MODEL SW SW (Ron 0.01 Roff 1g Vt 6V Vh 0)
TEXT -1224 680 Left 2 ;SPARE
TEXT -1912 416 Left 2 ;24V
TEXT -776 416 Left 2 ;12V