On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>s�ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: >> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> >> wrote: >> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund >> ><klaus.k...@gmail.com> wrote: >> > >> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: >> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund >> >>> <klaus.k...@gmail.com> wrote: >> >>> >> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: >> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund >> >>> >> <klaus.k...@gmail.com> wrote: >> >>> >> >Hi >> >>> >> > >> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> >>> >> > >> >>> >> >I know Larkin has used the DRQ127 >> >>> >> > >> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> >>> >> > >> >>> >> >But, I am looking to see if I can find bottom dollar. >> >>> >> > >> >>> >> >I probably wont go to LCSC, so would prefer a known brand. >> >>> >> > >> >>> >> >Anyone got a recommendation? >> >>> >> > >> >>> >> >Cheers >> >>> >> > >> >>> >> >Klaus >> >>> >> Are you driving the gate of a fet? What fet? >> >>> > >> >>> >STB43N60DM2 >> >>> > >> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. >> >>> > >> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. >> >>> > >> >>> >Schematics, first draft: >> >>> > >> >>> >www.electronicsdesign.dk/tmp/ssr.pdf >> >>> > >> >>> >Some comments: >> >>> > >> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. >> >>> > >> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out � lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. >> >>> > >> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. >> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. >> >>> > >> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. >> >>> >MOSFETs are avalanche rated for 800mJ. >> >>> > >> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. >> >>> >Rth = 40K/W. Transient Rth = 0.6K/W >> >>> Since you have that 230 VAC source, you could make a gate power supply >> >>> from that. The little capacitor-limited thing like people use to power >> >>> LEDs from the AC line. >> >>> >> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. >> > >> >Sure, the LED night-light circuits include a series resistor. >> > >> >The totem-pole opto gate driver needs about zero supply current, so >> >the series resistor can be big. Actually, the series resistor would >> >work without a series cap. I can sketch it if it's not all clear. >> >After this coffee diffuses into my brain. >> > >> > >> You could do your entire isolated gate driver for about 17 cents. > >something like this?Close. I was thinking https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 One could add a zener somewhere without blowing the 17 cent budget.> >Version 4 >SHEET 1 960 800 >WIRE 64 -112 -64 -112 >WIRE 272 -112 144 -112 >WIRE 688 -112 272 -112 >WIRE 272 -64 272 -112 >WIRE -64 0 -64 -112 >WIRE 688 64 688 -112 >WIRE 272 96 272 16 >WIRE -64 112 -64 64 >WIRE -64 112 -160 112 >WIRE 80 112 -64 112 >WIRE -160 144 -160 112 >WIRE -64 144 -64 112 >WIRE 224 176 144 176 >WIRE -64 208 -160 208 >WIRE 176 208 -64 208 >WIRE 272 208 272 192 >WIRE 272 208 176 208 >WIRE 272 224 272 208 >WIRE 224 240 224 176 >WIRE 272 384 272 320 >WIRE 688 384 688 144 >WIRE 688 384 272 384 >WIRE -144 432 -560 432 >WIRE 80 432 80 112 >WIRE 80 432 48 432 >WIRE 80 496 48 496 >WIRE -304 528 -336 528 >WIRE -144 528 -224 528 >WIRE 80 576 80 496 >WIRE 144 576 144 176 >WIRE 144 576 80 576 >WIRE -336 624 -336 528 >WIRE -336 624 -416 624 >WIRE -304 624 -336 624 >WIRE -144 624 -224 624 >WIRE 80 624 80 576 >WIRE 80 624 48 624 >WIRE -560 640 -560 432 >WIRE -416 640 -416 624 >WIRE 176 688 176 208 >WIRE 176 688 48 688 >WIRE -416 720 -560 720 >WIRE -144 720 -416 720 >FLAG -560 720 0 >FLAG -64 208 0 >SYMBOL nmos 224 96 R0 >SYMATTR InstName M1 >SYMATTR Value R6020PNJ >SYMBOL nmos 224 320 M180 >SYMATTR InstName M2 >SYMATTR Value R6020PNJ >SYMBOL res 256 -80 R0 >SYMATTR InstName R1 >SYMATTR Value 70 >SYMBOL voltage 688 48 R0 >WINDOW 123 0 0 Left 0 >WINDOW 39 0 0 Left 0 >SYMATTR InstName V1 >SYMATTR Value SINE(0 325 50 0 0 0) >SYMBOL diode -80 0 R0 >SYMATTR InstName D1 >SYMATTR Value MUR460 >SYMBOL zener -144 208 R180 >WINDOW 0 24 64 Left 2 >WINDOW 3 24 0 Left 2 >SYMATTR InstName D2 >SYMATTR Value BZX84C10L >SYMATTR Description Diode >SYMATTR Type diode >SYMBOL res 160 -128 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R2 >SYMATTR Value 500k >SYMBOL cap -80 144 R0 >SYMATTR InstName C1 >SYMATTR Value 100n >SYMBOL Optos\\4N25 -48 496 R0 >SYMATTR InstName U1 >SYMBOL Optos\\4N25 -48 688 R0 >SYMATTR InstName U2 >SYMBOL voltage -560 624 R0 >WINDOW 3 -65 60 Left 2 >WINDOW 123 0 0 Left 0 >WINDOW 39 0 0 Left 0 >SYMATTR InstName V2 >SYMATTR Value 2 >SYMBOL voltage -416 624 R0 >WINDOW 3 -74 146 Left 2 >WINDOW 123 0 0 Left 0 >WINDOW 39 0 0 Left 0 >SYMATTR InstName V3 >SYMATTR Value PULSE(2 0 .1 1u 1u .1205 .3457) >SYMBOL res -208 512 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R3 >SYMATTR Value 100 >SYMBOL res -208 608 R90 >WINDOW 0 0 56 VBottom 2 >WINDOW 3 32 56 VTop 2 >SYMATTR InstName R4 >SYMATTR Value 100 >TEXT -326 -184 Left 2 !.tran 2 > >
Cheap pulse 1:1 transformer
Started by ●November 9, 2023
Reply by ●November 12, 20232023-11-12
Reply by ●November 12, 20232023-11-12
On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <jl@997PotHill.com> wrote:>On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen ><langwadt@fonz.dk> wrote: > >>s�ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> >>> wrote: >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund >>> ><klaus.k...@gmail.com> wrote: >>> > >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund >>> >>> <klaus.k...@gmail.com> wrote: >>> >>> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund >>> >>> >> <klaus.k...@gmail.com> wrote: >>> >>> >> >Hi >>> >>> >> > >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >>> >>> >> > >>> >>> >> >I know Larkin has used the DRQ127 >>> >>> >> > >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >>> >>> >> > >>> >>> >> >But, I am looking to see if I can find bottom dollar. >>> >>> >> > >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. >>> >>> >> > >>> >>> >> >Anyone got a recommendation? >>> >>> >> > >>> >>> >> >Cheers >>> >>> >> > >>> >>> >> >Klaus >>> >>> >> Are you driving the gate of a fet? What fet? >>> >>> > >>> >>> >STB43N60DM2 >>> >>> > >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. >>> >>> > >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. >>> >>> > >>> >>> >Schematics, first draft: >>> >>> > >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf >>> >>> > >>> >>> >Some comments: >>> >>> > >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. >>> >>> > >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out � lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. >>> >>> > >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. >>> >>> > >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. >>> >>> >MOSFETs are avalanche rated for 800mJ. >>> >>> > >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W >>> >>> Since you have that 230 VAC source, you could make a gate power supply >>> >>> from that. The little capacitor-limited thing like people use to power >>> >>> LEDs from the AC line. >>> >>> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. >>> > >>> >Sure, the LED night-light circuits include a series resistor. >>> > >>> >The totem-pole opto gate driver needs about zero supply current, so >>> >the series resistor can be big. Actually, the series resistor would >>> >work without a series cap. I can sketch it if it's not all clear. >>> >After this coffee diffuses into my brain. >>> > >>> > >>> You could do your entire isolated gate driver for about 17 cents. >> >>something like this? > >Close. I was thinking > >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 > >One could add a zener somewhere without blowing the 17 cent budget. > >That needs to be Spiced. It gets a little weird when the fets are off. It may need another resistor.
Reply by ●November 12, 20232023-11-12
søndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin:> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> > wrote: > >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen > ><lang...@fonz.dk> wrote: > > > >>sřndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: > >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> > >>> wrote: > >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund > >>> ><klaus.k...@gmail.com> wrote: > >>> > > >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: > >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund > >>> >>> <klaus.k...@gmail.com> wrote: > >>> >>> > >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: > >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund > >>> >>> >> <klaus.k...@gmail.com> wrote: > >>> >>> >> >Hi > >>> >>> >> > > >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > >>> >>> >> > > >>> >>> >> >I know Larkin has used the DRQ127 > >>> >>> >> > > >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > >>> >>> >> > > >>> >>> >> >But, I am looking to see if I can find bottom dollar. > >>> >>> >> > > >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. > >>> >>> >> > > >>> >>> >> >Anyone got a recommendation? > >>> >>> >> > > >>> >>> >> >Cheers > >>> >>> >> > > >>> >>> >> >Klaus > >>> >>> >> Are you driving the gate of a fet? What fet? > >>> >>> > > >>> >>> >STB43N60DM2 > >>> >>> > > >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. > >>> >>> > > >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. > >>> >>> > > >>> >>> >Schematics, first draft: > >>> >>> > > >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf > >>> >>> > > >>> >>> >Some comments: > >>> >>> > > >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. > >>> >>> > > >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out – lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. > >>> >>> > > >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. > >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. > >>> >>> > > >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. > >>> >>> >MOSFETs are avalanche rated for 800mJ. > >>> >>> > > >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. > >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W > >>> >>> Since you have that 230 VAC source, you could make a gate power supply > >>> >>> from that. The little capacitor-limited thing like people use to power > >>> >>> LEDs from the AC line. > >>> >>> > >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. > >>> > > >>> >Sure, the LED night-light circuits include a series resistor. > >>> > > >>> >The totem-pole opto gate driver needs about zero supply current, so > >>> >the series resistor can be big. Actually, the series resistor would > >>> >work without a series cap. I can sketch it if it's not all clear. > >>> >After this coffee diffuses into my brain. > >>> > > >>> > > >>> You could do your entire isolated gate driver for about 17 cents. > >> > >>something like this? > > > >Close. I was thinking > > > >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 > > > >One could add a zener somewhere without blowing the 17 cent budget. > > > > > That needs to be Spiced. It gets a little weird when the fets are off. > It may need another resistor.it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground
Reply by ●November 12, 20232023-11-12
On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>s�ndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> >> wrote: >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen >> ><lang...@fonz.dk> wrote: >> > >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> >> >>> wrote: >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund >> >>> ><klaus.k...@gmail.com> wrote: >> >>> > >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund >> >>> >>> <klaus.k...@gmail.com> wrote: >> >>> >>> >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund >> >>> >>> >> <klaus.k...@gmail.com> wrote: >> >>> >>> >> >Hi >> >>> >>> >> > >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> >>> >>> >> > >> >>> >>> >> >I know Larkin has used the DRQ127 >> >>> >>> >> > >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> >>> >>> >> > >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. >> >>> >>> >> > >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. >> >>> >>> >> > >> >>> >>> >> >Anyone got a recommendation? >> >>> >>> >> > >> >>> >>> >> >Cheers >> >>> >>> >> > >> >>> >>> >> >Klaus >> >>> >>> >> Are you driving the gate of a fet? What fet? >> >>> >>> > >> >>> >>> >STB43N60DM2 >> >>> >>> > >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. >> >>> >>> > >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. >> >>> >>> > >> >>> >>> >Schematics, first draft: >> >>> >>> > >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf >> >>> >>> > >> >>> >>> >Some comments: >> >>> >>> > >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. >> >>> >>> > >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out � lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. >> >>> >>> > >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. >> >>> >>> > >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. >> >>> >>> >MOSFETs are avalanche rated for 800mJ. >> >>> >>> > >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply >> >>> >>> from that. The little capacitor-limited thing like people use to power >> >>> >>> LEDs from the AC line. >> >>> >>> >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. >> >>> > >> >>> >Sure, the LED night-light circuits include a series resistor. >> >>> > >> >>> >The totem-pole opto gate driver needs about zero supply current, so >> >>> >the series resistor can be big. Actually, the series resistor would >> >>> >work without a series cap. I can sketch it if it's not all clear. >> >>> >After this coffee diffuses into my brain. >> >>> > >> >>> > >> >>> You could do your entire isolated gate driver for about 17 cents. >> >> >> >>something like this? >> > >> >Close. I was thinking >> > >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 >> > >> >One could add a zener somewhere without blowing the 17 cent budget. >> > >> > >> That needs to be Spiced. It gets a little weird when the fets are off. >> It may need another resistor. > >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the groundThe source-source node basically floats when both fets are off... battling substrate diodes. So the power supply to the totem-pole opto could fail. Fixing this could run the total cost up to 18 cents.
Reply by ●November 12, 20232023-11-12
mandag den 13. november 2023 kl. 00.32.30 UTC+1 skrev John Larkin:> On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen > <lang...@fonz.dk> wrote: > > >søndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: > >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> > >> wrote: > >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen > >> ><lang...@fonz.dk> wrote: > >> > > >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: > >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> > >> >>> wrote: > >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund > >> >>> ><klaus.k...@gmail.com> wrote: > >> >>> > > >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: > >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund > >> >>> >>> <klaus.k...@gmail.com> wrote: > >> >>> >>> > >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: > >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund > >> >>> >>> >> <klaus.k...@gmail.com> wrote: > >> >>> >>> >> >Hi > >> >>> >>> >> > > >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > >> >>> >>> >> > > >> >>> >>> >> >I know Larkin has used the DRQ127 > >> >>> >>> >> > > >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > >> >>> >>> >> > > >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. > >> >>> >>> >> > > >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. > >> >>> >>> >> > > >> >>> >>> >> >Anyone got a recommendation? > >> >>> >>> >> > > >> >>> >>> >> >Cheers > >> >>> >>> >> > > >> >>> >>> >> >Klaus > >> >>> >>> >> Are you driving the gate of a fet? What fet? > >> >>> >>> > > >> >>> >>> >STB43N60DM2 > >> >>> >>> > > >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. > >> >>> >>> > > >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. > >> >>> >>> > > >> >>> >>> >Schematics, first draft: > >> >>> >>> > > >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf > >> >>> >>> > > >> >>> >>> >Some comments: > >> >>> >>> > > >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. > >> >>> >>> > > >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out – lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. > >> >>> >>> > > >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. > >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. > >> >>> >>> > > >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. > >> >>> >>> >MOSFETs are avalanche rated for 800mJ. > >> >>> >>> > > >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. > >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W > >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply > >> >>> >>> from that. The little capacitor-limited thing like people use to power > >> >>> >>> LEDs from the AC line. > >> >>> >>> > >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. > >> >>> > > >> >>> >Sure, the LED night-light circuits include a series resistor. > >> >>> > > >> >>> >The totem-pole opto gate driver needs about zero supply current, so > >> >>> >the series resistor can be big. Actually, the series resistor would > >> >>> >work without a series cap. I can sketch it if it's not all clear. > >> >>> >After this coffee diffuses into my brain. > >> >>> > > >> >>> > > >> >>> You could do your entire isolated gate driver for about 17 cents. > >> >> > >> >>something like this? > >> > > >> >Close. I was thinking > >> > > >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 > >> > > >> >One could add a zener somewhere without blowing the 17 cent budget. > >> > > >> > > >> That needs to be Spiced. It gets a little weird when the fets are off. > >> It may need another resistor. > > > >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground > The source-source node basically floats when both fets are off... > battling substrate diodes. So the power supply to the totem-pole opto > could fail.how? C1 gets charged via D1 and Q2s body diode
Reply by ●November 12, 20232023-11-12
On Sun, 12 Nov 2023 15:54:43 -0800 (PST), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>mandag den 13. november 2023 kl. 00.32.30 UTC+1 skrev John Larkin: >> On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen >> <lang...@fonz.dk> wrote: >> >> >s�ndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: >> >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> >> >> wrote: >> >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen >> >> ><lang...@fonz.dk> wrote: >> >> > >> >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: >> >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> >> >> >>> wrote: >> >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund >> >> >>> ><klaus.k...@gmail.com> wrote: >> >> >>> > >> >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: >> >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund >> >> >>> >>> <klaus.k...@gmail.com> wrote: >> >> >>> >>> >> >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: >> >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund >> >> >>> >>> >> <klaus.k...@gmail.com> wrote: >> >> >>> >>> >> >Hi >> >> >>> >>> >> > >> >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> >> >>> >>> >> > >> >> >>> >>> >> >I know Larkin has used the DRQ127 >> >> >>> >>> >> > >> >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> >> >>> >>> >> > >> >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. >> >> >>> >>> >> > >> >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. >> >> >>> >>> >> > >> >> >>> >>> >> >Anyone got a recommendation? >> >> >>> >>> >> > >> >> >>> >>> >> >Cheers >> >> >>> >>> >> > >> >> >>> >>> >> >Klaus >> >> >>> >>> >> Are you driving the gate of a fet? What fet? >> >> >>> >>> > >> >> >>> >>> >STB43N60DM2 >> >> >>> >>> > >> >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. >> >> >>> >>> > >> >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. >> >> >>> >>> > >> >> >>> >>> >Schematics, first draft: >> >> >>> >>> > >> >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf >> >> >>> >>> > >> >> >>> >>> >Some comments: >> >> >>> >>> > >> >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. >> >> >>> >>> > >> >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out � lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. >> >> >>> >>> > >> >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. >> >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. >> >> >>> >>> > >> >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. >> >> >>> >>> >MOSFETs are avalanche rated for 800mJ. >> >> >>> >>> > >> >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. >> >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W >> >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply >> >> >>> >>> from that. The little capacitor-limited thing like people use to power >> >> >>> >>> LEDs from the AC line. >> >> >>> >>> >> >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. >> >> >>> > >> >> >>> >Sure, the LED night-light circuits include a series resistor. >> >> >>> > >> >> >>> >The totem-pole opto gate driver needs about zero supply current, so >> >> >>> >the series resistor can be big. Actually, the series resistor would >> >> >>> >work without a series cap. I can sketch it if it's not all clear. >> >> >>> >After this coffee diffuses into my brain. >> >> >>> > >> >> >>> > >> >> >>> You could do your entire isolated gate driver for about 17 cents. >> >> >> >> >> >>something like this? >> >> > >> >> >Close. I was thinking >> >> > >> >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 >> >> > >> >> >One could add a zener somewhere without blowing the 17 cent budget. >> >> > >> >> > >> >> That needs to be Spiced. It gets a little weird when the fets are off. >> >> It may need another resistor. >> > >> >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground >> The source-source node basically floats when both fets are off... >> battling substrate diodes. So the power supply to the totem-pole opto >> could fail. > >how? C1 gets charged via D1 and Q2s body diodeYeah, OK, I guess it does work.
Reply by ●November 12, 20232023-11-12
On Monday, 13 November 2023 at 01:51:39 UTC+1, John Larkin wrote:> On Sun, 12 Nov 2023 15:54:43 -0800 (PST), Lasse Langwadt Christensen > <lang...@fonz.dk> wrote: > > >mandag den 13. november 2023 kl. 00.32.30 UTC+1 skrev John Larkin: > >> On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen > >> <lang...@fonz.dk> wrote: > >> > >> >sřndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: > >> >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> > >> >> wrote: > >> >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen > >> >> ><lang...@fonz.dk> wrote: > >> >> > > >> >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: > >> >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> > >> >> >>> wrote: > >> >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund > >> >> >>> ><klaus.k...@gmail.com> wrote: > >> >> >>> > > >> >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: > >> >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund > >> >> >>> >>> <klaus.k...@gmail.com> wrote: > >> >> >>> >>> > >> >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: > >> >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund > >> >> >>> >>> >> <klaus.k...@gmail.com> wrote: > >> >> >>> >>> >> >Hi > >> >> >>> >>> >> > > >> >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > >> >> >>> >>> >> > > >> >> >>> >>> >> >I know Larkin has used the DRQ127 > >> >> >>> >>> >> > > >> >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > >> >> >>> >>> >> > > >> >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. > >> >> >>> >>> >> > > >> >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. > >> >> >>> >>> >> > > >> >> >>> >>> >> >Anyone got a recommendation? > >> >> >>> >>> >> > > >> >> >>> >>> >> >Cheers > >> >> >>> >>> >> > > >> >> >>> >>> >> >Klaus > >> >> >>> >>> >> Are you driving the gate of a fet? What fet? > >> >> >>> >>> > > >> >> >>> >>> >STB43N60DM2 > >> >> >>> >>> > > >> >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. > >> >> >>> >>> > > >> >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. > >> >> >>> >>> > > >> >> >>> >>> >Schematics, first draft: > >> >> >>> >>> > > >> >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf > >> >> >>> >>> > > >> >> >>> >>> >Some comments: > >> >> >>> >>> > > >> >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. > >> >> >>> >>> > > >> >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out – lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. > >> >> >>> >>> > > >> >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. > >> >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. > >> >> >>> >>> > > >> >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. > >> >> >>> >>> >MOSFETs are avalanche rated for 800mJ. > >> >> >>> >>> > > >> >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. > >> >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W > >> >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply > >> >> >>> >>> from that. The little capacitor-limited thing like people use to power > >> >> >>> >>> LEDs from the AC line. > >> >> >>> >>> > >> >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. > >> >> >>> > > >> >> >>> >Sure, the LED night-light circuits include a series resistor. > >> >> >>> > > >> >> >>> >The totem-pole opto gate driver needs about zero supply current, so > >> >> >>> >the series resistor can be big. Actually, the series resistor would > >> >> >>> >work without a series cap. I can sketch it if it's not all clear. > >> >> >>> >After this coffee diffuses into my brain. > >> >> >>> > > >> >> >>> > > >> >> >>> You could do your entire isolated gate driver for about 17 cents. > >> >> >> > >> >> >>something like this? > >> >> > > >> >> >Close. I was thinking > >> >> > > >> >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 > >> >> > > >> >> >One could add a zener somewhere without blowing the 17 cent budget. > >> >> > > >> >> > > >> >> That needs to be Spiced. It gets a little weird when the fets are off. > >> >> It may need another resistor. > >> > > >> >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground > >> The source-source node basically floats when both fets are off... > >> battling substrate diodes. So the power supply to the totem-pole opto > >> could fail. > > > >how? C1 gets charged via D1 and Q2s body diode > Yeah, OK, I guess it does work.Very nice solution, and a lot more clean than the transformer one I have been working on. Only worry is noise coupling into the gates, from transients. But that can be remedied by adding a capacitance to the gates of Q1 and Q2. Will slow switching times a little, but more robust.
Reply by ●November 12, 20232023-11-12
On Monday, 13 November 2023 at 02:37:13 UTC+1, Klaus Kragelund wrote:> On Monday, 13 November 2023 at 01:51:39 UTC+1, John Larkin wrote: > > On Sun, 12 Nov 2023 15:54:43 -0800 (PST), Lasse Langwadt Christensen > > <lang...@fonz.dk> wrote: > > > > >mandag den 13. november 2023 kl. 00.32.30 UTC+1 skrev John Larkin: > > >> On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen > > >> <lang...@fonz.dk> wrote: > > >> > > >> >sřndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: > > >> >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> > > >> >> wrote: > > >> >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen > > >> >> ><lang...@fonz.dk> wrote: > > >> >> > > > >> >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: > > >> >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> > > >> >> >>> wrote: > > >> >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund > > >> >> >>> ><klaus.k...@gmail.com> wrote: > > >> >> >>> > > > >> >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: > > >> >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund > > >> >> >>> >>> <klaus.k...@gmail.com> wrote: > > >> >> >>> >>> > > >> >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: > > >> >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund > > >> >> >>> >>> >> <klaus.k...@gmail.com> wrote: > > >> >> >>> >>> >> >Hi > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >I know Larkin has used the DRQ127 > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >Anyone got a recommendation? > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >Cheers > > >> >> >>> >>> >> > > > >> >> >>> >>> >> >Klaus > > >> >> >>> >>> >> Are you driving the gate of a fet? What fet? > > >> >> >>> >>> > > > >> >> >>> >>> >STB43N60DM2 > > >> >> >>> >>> > > > >> >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. > > >> >> >>> >>> > > > >> >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. > > >> >> >>> >>> > > > >> >> >>> >>> >Schematics, first draft: > > >> >> >>> >>> > > > >> >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf > > >> >> >>> >>> > > > >> >> >>> >>> >Some comments: > > >> >> >>> >>> > > > >> >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. > > >> >> >>> >>> > > > >> >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out – lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. > > >> >> >>> >>> > > > >> >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. > > >> >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. > > >> >> >>> >>> > > > >> >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. > > >> >> >>> >>> >MOSFETs are avalanche rated for 800mJ. > > >> >> >>> >>> > > > >> >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. > > >> >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W > > >> >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply > > >> >> >>> >>> from that. The little capacitor-limited thing like people use to power > > >> >> >>> >>> LEDs from the AC line. > > >> >> >>> >>> > > >> >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. > > >> >> >>> > > > >> >> >>> >Sure, the LED night-light circuits include a series resistor. > > >> >> >>> > > > >> >> >>> >The totem-pole opto gate driver needs about zero supply current, so > > >> >> >>> >the series resistor can be big. Actually, the series resistor would > > >> >> >>> >work without a series cap. I can sketch it if it's not all clear. > > >> >> >>> >After this coffee diffuses into my brain. > > >> >> >>> > > > >> >> >>> > > > >> >> >>> You could do your entire isolated gate driver for about 17 cents. > > >> >> >> > > >> >> >>something like this? > > >> >> > > > >> >> >Close. I was thinking > > >> >> > > > >> >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 > > >> >> > > > >> >> >One could add a zener somewhere without blowing the 17 cent budget. > > >> >> > > > >> >> > > > >> >> That needs to be Spiced. It gets a little weird when the fets are off. > > >> >> It may need another resistor. > > >> > > > >> >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground > > >> The source-source node basically floats when both fets are off... > > >> battling substrate diodes. So the power supply to the totem-pole opto > > >> could fail. > > > > > >how? C1 gets charged via D1 and Q2s body diode > > Yeah, OK, I guess it does work. > Very nice solution, and a lot more clean than the transformer one I have been working on. > > Only worry is noise coupling into the gates, from transients. But that can be remedied by adding a capacitance to the gates of Q1 and Q2. Will slow switching times a little, but more robust.I just simulated Lasses solution. C1 needs to be 1uF due to charge transfer, otherwise the switching losses are too high
Reply by ●November 13, 20232023-11-13
On Sun, 12 Nov 2023 17:52:25 -0800 (PST), Klaus Kragelund <klaus.kragelund@gmail.com> wrote:>On Monday, 13 November 2023 at 02:37:13 UTC+1, Klaus Kragelund wrote: >> On Monday, 13 November 2023 at 01:51:39 UTC+1, John Larkin wrote: >> > On Sun, 12 Nov 2023 15:54:43 -0800 (PST), Lasse Langwadt Christensen >> > <lang...@fonz.dk> wrote: >> > >> > >mandag den 13. november 2023 kl. 00.32.30 UTC+1 skrev John Larkin: >> > >> On Sun, 12 Nov 2023 13:53:18 -0800 (PST), Lasse Langwadt Christensen >> > >> <lang...@fonz.dk> wrote: >> > >> >> > >> >s?ndag den 12. november 2023 kl. 21.59.15 UTC+1 skrev John Larkin: >> > >> >> On Sun, 12 Nov 2023 11:55:40 -0800, John Larkin <j...@997PotHill.com> >> > >> >> wrote: >> > >> >> >On Sun, 12 Nov 2023 11:00:03 -0800 (PST), Lasse Langwadt Christensen >> > >> >> ><lang...@fonz.dk> wrote: >> > >> >> > >> > >> >> >>s?ndag den 12. november 2023 kl. 18.15.35 UTC+1 skrev John Larkin: >> > >> >> >>> On Sun, 12 Nov 2023 07:44:41 -0800, John Larkin <j...@997PotHill.com> >> > >> >> >>> wrote: >> > >> >> >>> >On Sun, 12 Nov 2023 03:29:02 -0800 (PST), Klaus Kragelund >> > >> >> >>> ><klaus.k...@gmail.com> wrote: >> > >> >> >>> > >> > >> >> >>> >>On Sunday, 12 November 2023 at 01:02:21 UTC+1, John Larkin wrote: >> > >> >> >>> >>> On Sat, 11 Nov 2023 14:57:11 -0800 (PST), Klaus Kragelund >> > >> >> >>> >>> <klaus.k...@gmail.com> wrote: >> > >> >> >>> >>> >> > >> >> >>> >>> >On Friday, 10 November 2023 at 16:28:14 UTC+1, John Larkin wrote: >> > >> >> >>> >>> >> On Thu, 9 Nov 2023 15:14:53 -0800 (PST), Klaus Kragelund >> > >> >> >>> >>> >> <klaus.k...@gmail.com> wrote: >> > >> >> >>> >>> >> >Hi >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >I am on the lookout for a cheap 1:1 pulse transformer. Will be using it to drive a MOSFET based Solid State Switch. >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >I know Larkin has used the DRQ127 >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >https://www.digikey.dk/en/products/detail/eaton-electronics-division/DRQ127-1R5-R/667262 >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >But, I am looking to see if I can find bottom dollar. >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >I probably wont go to LCSC, so would prefer a known brand. >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >Anyone got a recommendation? >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >Cheers >> > >> >> >>> >>> >> > >> > >> >> >>> >>> >> >Klaus >> > >> >> >>> >>> >> Are you driving the gate of a fet? What fet? >> > >> >> >>> >>> > >> > >> >> >>> >>> >STB43N60DM2 >> > >> >> >>> >>> > >> > >> >> >>> >>> >I did a change to the design, since the 1:10 transformer was bugging me, so used a old fashion CD4093 from 15V supply, to make an isolated supply with a 1:1 transformer. >> > >> >> >>> >>> > >> > >> >> >>> >>> >Then an opto to contol the MOSFETs. Emitter followers to lower the impedance driving the gate, since the turn on/turn off losses needs to be kept low due to transient thermal resistance. >> > >> >> >>> >>> > >> > >> >> >>> >>> >Schematics, first draft: >> > >> >> >>> >>> > >> > >> >> >>> >>> >www.electronicsdesign.dk/tmp/ssr.pdf >> > >> >> >>> >>> > >> > >> >> >>> >>> >Some comments: >> > >> >> >>> >>> > >> > >> >> >>> >>> >UVLO is handled by the microcontroller in that the PSU starts when power is applied, but the microcontroller is not allowed to turn the FET on until we are sure the PSU is active (milliseconds). Likewise, during shutdown the microcontroller first disables the opto. >> > >> >> >>> >>> > >> > >> >> >>> >>> >We need to have UVLO detection on the 15V power supply for the self-running oscillator, in case of a brown-out � lower voltage of the 15V node, the opto needs to be turned off before voltage sags deeper. Normally, if power is lost, then the switch off loss is also zero, but we could have a situation with low mains voltage and we need to take actions accordingly. >> > >> >> >>> >>> > >> > >> >> >>> >>> >MOSFET selected is STB43N60DM2, 100mohm/D2PAK, about 40K/W with current layout. >> > >> >> >>> >>> >At 100mohm/3.7A, loss is 1.3W. 600V device to have 60% derating from peak of 360V. >> > >> >> >>> >>> > >> > >> >> >>> >>> >275V varistor SIOV1 is placed across drain/drain of MOSFETs. We might be able to use lower voltage rated MOSFETs due to thje varistor. >> > >> >> >>> >>> >MOSFETs are avalanche rated for 800mJ. >> > >> >> >>> >>> > >> > >> >> >>> >>> >K = 0.015 for less than 10us switching time. Estimated for 1us.. >> > >> >> >>> >>> >Rth = 40K/W. Transient Rth = 0.6K/W >> > >> >> >>> >>> Since you have that 230 VAC source, you could make a gate power supply >> > >> >> >>> >>> from that. The little capacitor-limited thing like people use to power >> > >> >> >>> >>> LEDs from the AC line. >> > >> >> >>> >>> >> > >> >> >>> >>Actually the capacitive couplers are not very good when it comes to surges/transients on the mains line, so need to add impedance to reduce peak currents in the circuit. >> > >> >> >>> > >> > >> >> >>> >Sure, the LED night-light circuits include a series resistor. >> > >> >> >>> > >> > >> >> >>> >The totem-pole opto gate driver needs about zero supply current, so >> > >> >> >>> >the series resistor can be big. Actually, the series resistor would >> > >> >> >>> >work without a series cap. I can sketch it if it's not all clear. >> > >> >> >>> >After this coffee diffuses into my brain. >> > >> >> >>> > >> > >> >> >>> > >> > >> >> >>> You could do your entire isolated gate driver for about 17 cents. >> > >> >> >> >> > >> >> >>something like this? >> > >> >> > >> > >> >> >Close. I was thinking >> > >> >> > >> > >> >> >https://www.dropbox.com/scl/fi/ee9cpnt16nyxotka4zgkw/Isol_Gate_Driver_1.jpg?rlkey=v2o44hxa52eraurnuqpohmcp0&raw=1 >> > >> >> > >> > >> >> >One could add a zener somewhere without blowing the 17 cent budget. >> > >> >> > >> > >> >> > >> > >> >> That needs to be Spiced. It gets a little weird when the fets are off. >> > >> >> It may need another resistor. >> > >> > >> > >> >it should work, either way is a bit weird to look at in simulation if you don't make the fet sources the ground >> > >> The source-source node basically floats when both fets are off... >> > >> battling substrate diodes. So the power supply to the totem-pole opto >> > >> could fail. >> > > >> > >how? C1 gets charged via D1 and Q2s body diode >> > Yeah, OK, I guess it does work. >> Very nice solution, and a lot more clean than the transformer one I have been working on. >> >> Only worry is noise coupling into the gates, from transients. But that can be remedied by adding a capacitance to the gates of Q1 and Q2. Will slow switching times a little, but more robust. >I just simulated Lasses solution. C1 needs to be 1uF due to charge transfer, otherwise the switching losses are too highWhat sort of switching rates do you need? Entire cycles at 50 Hz? Fast PWM? The triac solution wouldn't switch fast, and a heater shouldn't need a lot of switching. You can vary the led drive, and the coupler CTRs, to control mosfet edge rates. I think EMI was an issue for you so you may not want fast edges. To go faster, add a couple of transistors to drive the gate capacitance harder. One PNP, one NPN, one cent each.
Reply by ●November 13, 20232023-11-13
On 2023-11-10 17:37, Fred Bloggs wrote:> Looks like the internet lost the Philips handbook...This one? https://assets.nexperia.com/documents/user-manual/Nexperia_document_book_MOSFETGaNFETApplicationHandbook_2020.pdf
