H Bridge, NMOS AND PMOS DRIVER
in [Design]
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From: sarah kent on 5 Aug 2010 16:26 Hello All, I am tring to generate a square wave of 100KHz and 200 volts peak to peak across a resistor via H- bridge. The current could go upto 30A. I am looking into two following ways to drive the NMOS ( four NMOS transistors ) H - bridge. 1. a. Using H bridge Drivers HIP4081A. I tried to look for the replacement of HIP4081A but only found A4940 from Allegro microsystems which a little slower than the HIP part regarding rise and fall time. According to my understanding the Driver chip has to charge the input capacitance of the transistors. I am planning to use NMOS transistor (IRF540). So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF and if power supply = 50Volts (60% of 50V = 30volts) , So, I calculated (1000pF x 30V) / 10nsec = 3 Amp. The gate to source charging capacitance of IRF540 is 14nC; So, the charging time would be (14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and in right direction? b. I calculated the same things using A4940 and found the following results (1000pF x 30V) / 35nsec = 857 mA (14nC x 30V) / (857mA) = 490nsec. Which proves that the A4940 is a slower part. But how will it effect the voltage waveform across the resistive load. I meant to say what would be the difference between the two waveforms generated by two different driver chips. Is there true replacement part available for HIP4081A. The reason for finding the replacement for HIP4081A are a. What if Intersil discontinue this part in the future. b. May be there is a cheapaer part available than HIP4081A. 2. The second method is to use four NPN transitors to drive two PMOS transistors (High side) and two NMOS (Low Side) transistors. Microcontroller will provide the PWM pulses to control the 2N2222 transistors. You can find the diagram at the following link. http://a.imageshack.us/img39/3520/201115.jpg I am thinking of using 2N2222A to drive two (IRF540N) but unable to find the PMOS equivalent of IRF540 N. Any suggestions!! Do I need them of the same ratings? Please also suggest that H - bridge driver approach is the better approach or the NPN transistors driving the PMOS and NMOS transistors is the good approach. I heard that the NPN driving the PMOS and NMOS is the most efficient way, if yes than how? Would 2N222 be able to charge the MOSFETS quickly as HIP4081A. What parameters should I consider before I choose the microcontroller. This is not a home work. :) Thanks Sarah
From: Tim Williams on 5 Aug 2010 19:09 "sarah kent" <sarah6541(a)gmail.com> wrote in message news:afad00db-3e31-493f-bd1e-7650e7abae39(a)k19g2000yqc.googlegroups.com... > Hello All, > > I am tring to generate a square wave of 100KHz and 200 volts peak to > peak across a resistor via H- bridge. The current could go upto 30A. AC only, no DC? Variable duty cycle? If so, what kind (balanced ala TL494 or differential ala class D audio)? Especially if the supply is line-operated (maybe this won't be an option for your load, I don't have a clue), I like to drive AC-only, balanced-PWM loads with a gate drive transformer. This can be driven directly from a TL598 (or UC3525, or...), or your choice of gate driver (as long as it's not a complementary emitter follower type). > I am looking into two following ways to drive the NMOS ( four NMOS > transistors ) H - bridge. > > 1. > > a. Using H bridge Drivers HIP4081A. I tried to look for the > replacement of HIP4081A but only found A4940 from Allegro microsystems > which a little slower than the HIP part regarding rise and fall time. Do you have a spec for how fast you need to run? 100ns is fine at 100kHz, you'll most likely burn more power in conduction than switching. Anything faster is a bonus, but not particularly useful (and could be dangerous, due to higher dI/dt forcing improved layout!). > According to my understanding the Driver chip has to charge the input > capacitance of the transistors. I am planning to use NMOS transistor > (IRF540). Whaaa? Did you read the Vds(max) on that!? 200Vp-p needs a 100V power supply. That means >150V transistors! > So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF and > if power supply = 50Volts (60% of 50V = 30volts) , So, I calculated > (1000pF x 30V) / 10nsec = 3 Amp. > > The gate to source charging capacitance of IRF540 is 14nC; So, the > charging time would be > > (14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and in > right direction? No, C == A.s, so 14nAs * 30V = 420nVAs == nJ (energy). Divide by amps gets you Vs, which is flux, not time. Since C == A.s, 14nC / 3A = 4.67ns. This is less than the rated t_r so it will be chip-limited, not capacitance-limited. > Which proves that the A4940 is a slower part. But how will it effect > the voltage waveform across the resistive load. I meant to say what > would be the difference between the two waveforms generated by two > different driver chips. Likely the HIP is faster. You'd use it if you needed to drive particularly large FETs particularly fast. If you don't need the speed, don't put down the money for it. A regular IR2112 is enough for mere IRF540s at 100kHz. Well, a little sluggish for 100k, more like 50k for best results, but still not bad. > 2. The second method is to use four NPN transitors to drive two PMOS > transistors (High side) and two NMOS (Low Side) transistors. No. Check Vgs(max). Complementary MOS is impossible over 20V supply without extra circuitry, which adds enough complexity that you are better off with a driver chip and NMOS (which work better anyway). > Microcontroller will provide the PWM pulses to control the 2N2222 > transistors. You can find the diagram at the following link. > > http://a.imageshack.us/img39/3520/201115.jpg > > I am thinking of using 2N2222A to drive two (IRF540N) but unable to > find the PMOS equivalent of IRF540 N. Any suggestions!! Do I need them > of the same ratings? > > Please also suggest that H - bridge driver approach is the better > approach or the NPN transistors driving the PMOS and NMOS transistors > is the good approach. I heard that the NPN driving the PMOS and NMOS > is the most efficient way, if yes than how? > > Would 2N222 be able to charge the MOSFETS quickly as HIP4081A. Nope: 2N222 Low Power, General Purpose, Ge, PNP, 70mW, 15V, 12V, 70mA, 85>C, 400KHz, 70, 20T, RCA, TO1 Neato, it's germanium, 400kHz fT. :^) Typoes aside, forget 2N2222 anyway. Like 2N3055 and LM741, it is ancient and best left forgotten, thrown to the gutter, on the road of progress. 2N4401/03 are quite reasonable substitutes, and there are numerous others with even better performance if you insist on rolling your own gate drive. ZTX651 comes to mind, it's even smaller than 2N4401 yet drives 3A peak quite easily. TC4420 and similar are quite popular for big jobs (6A peak, good for monster IGBTs). Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms
From: sarah kent on 5 Aug 2010 20:33 On Aug 5, 7:09 pm, "Tim Williams" <tmoran...(a)charter.net> wrote: > "sarah kent" <sarah6...(a)gmail.com> wrote in message > > news:afad00db-3e31-493f-bd1e-7650e7abae39(a)k19g2000yqc.googlegroups.com... > > > Hello All, > > > I am tring to generate a square wave of 100KHz and 200 volts peak to > > peak across a resistor via H- bridge. The current could go upto 30A. > > AC only, no DC? Variable duty cycle? If so, what kind (balanced ala > TL494 or differential ala class D audio)? > > Especially if the supply is line-operated (maybe this won't be an option > for your load, I don't have a clue), I like to drive AC-only, balanced-PWM > loads with a gate drive transformer. This can be driven directly from a > TL598 (or UC3525, or...), or your choice of gate driver (as long as it's > not a complementary emitter follower type). > > > I am looking into two following ways to drive the NMOS ( four NMOS > > transistors ) H - bridge. > > > 1. > > > a. Using H bridge Drivers HIP4081A. I tried to look for the > > replacement of HIP4081A but only found A4940 from Allegro microsystems > > which a little slower than the HIP part regarding rise and fall time. > > Do you have a spec for how fast you need to run? 100ns is fine at 100kHz, > you'll most likely burn more power in conduction than switching. Anything > faster is a bonus, but not particularly useful (and could be dangerous, > due to higher dI/dt forcing improved layout!). > > > According to my understanding the Driver chip has to charge the input > > capacitance of the transistors. I am planning to use NMOS transistor > > (IRF540). > > Whaaa? Did you read the Vds(max) on that!? 200Vp-p needs a 100V power > supply. That means >150V transistors! > > > So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF and > > if power supply = 50Volts (60% of 50V = 30volts) , So, I calculated > > (1000pF x 30V) / 10nsec = 3 Amp. > > > The gate to source charging capacitance of IRF540 is 14nC; So, the > > charging time would be > > > (14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and in > > right direction? > > No, C == A.s, so 14nAs * 30V = 420nVAs == nJ (energy). Divide by amps > gets you Vs, which is flux, not time. > > Since C == A.s, 14nC / 3A = 4.67ns. This is less than the rated t_r so it > will be chip-limited, not capacitance-limited. > > > Which proves that the A4940 is a slower part. But how will it effect > > the voltage waveform across the resistive load. I meant to say what > > would be the difference between the two waveforms generated by two > > different driver chips. > > Likely the HIP is faster. You'd use it if you needed to drive > particularly large FETs particularly fast. If you don't need the speed, > don't put down the money for it. A regular IR2112 is enough for mere > IRF540s at 100kHz. Well, a little sluggish for 100k, more like 50k for > best results, but still not bad. > > > 2. The second method is to use four NPN transitors to drive two PMOS > > transistors (High side) and two NMOS (Low Side) transistors. > > No. Check Vgs(max). Complementary MOS is impossible over 20V supply > without extra circuitry, which adds enough complexity that you are better > off with a driver chip and NMOS (which work better anyway). > > > Microcontroller will provide the PWM pulses to control the 2N2222 > > transistors. You can find the diagram at the following link. > > >http://a.imageshack.us/img39/3520/201115.jpg > > > I am thinking of using 2N2222A to drive two (IRF540N) but unable to > > find the PMOS equivalent of IRF540 N. Any suggestions!! Do I need them > > of the same ratings? > > > Please also suggest that H - bridge driver approach is the better > > approach or the NPN transistors driving the PMOS and NMOS transistors > > is the good approach. I heard that the NPN driving the PMOS and NMOS > > is the most efficient way, if yes than how? > > > Would 2N222 be able to charge the MOSFETS quickly as HIP4081A. > > Nope: > > 2N222 > Low Power, General Purpose, Ge, PNP, 70mW, 15V, 12V, 70mA, 85>C, 400KHz, > 70, 20T, RCA, TO1 > > Neato, it's germanium, 400kHz fT. :^) > > Typoes aside, forget 2N2222 anyway. Like 2N3055 and LM741, it is ancient > and best left forgotten, thrown to the gutter, on the road of progress. > 2N4401/03 are quite reasonable substitutes, and there are numerous others > with even better performance if you insist on rolling your own gate drive.. > ZTX651 comes to mind, it's even smaller than 2N4401 yet drives 3A peak > quite easily. TC4420 and similar are quite popular for big jobs (6A peak, > good for monster IGBTs). > > Tim > > -- > Deep Friar: a very philosophical monk. > Website:http://webpages.charter.net/dawill/tmoranwms Hi, Thanks for the reply. I have following questions 1. Why complementary MOSFET scheme can not work with power supply greater than 20 Volts? 2. Is there a way that I can generate the sine wave of 200 volts peak to peak at 100KHz with out using H bridge driver or four MOSFETS? Sarah
From: John Larkin on 5 Aug 2010 21:07 On Thu, 5 Aug 2010 13:26:13 -0700 (PDT), sarah kent <sarah6541(a)gmail.com> wrote: >Hello All, > >I am tring to generate a square wave of 100KHz and 200 volts peak to >peak across a resistor via H- bridge. The current could go upto 30A. > > >I am looking into two following ways to drive the NMOS ( four NMOS >transistors ) H - bridge. > >1. > >a. Using H bridge Drivers HIP4081A. I tried to look for the >replacement of HIP4081A but only found A4940 from Allegro microsystems >which a little slower than the HIP part regarding rise and fall time. >According to my understanding the Driver chip has to charge the input >capacitance of the transistors. I am planning to use NMOS transistor >(IRF540). > >So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF and >if power supply = 50Volts (60% of 50V = 30volts) , So, I calculated >(1000pF x 30V) / 10nsec = 3 Amp. > >The gate to source charging capacitance of IRF540 is 14nC; So, the >charging time would be > >(14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and in >right direction? > >b. I calculated the same things using A4940 and found the following >results > >(1000pF x 30V) / 35nsec = 857 mA > >(14nC x 30V) / (857mA) = 490nsec. > >Which proves that the A4940 is a slower part. But how will it effect >the voltage waveform across the resistive load. I meant to say what >would be the difference between the two waveforms generated by two >different driver chips. > >Is there true replacement part available for HIP4081A. The reason for >finding the replacement for HIP4081A are > >a. What if Intersil discontinue this part in the future. >b. May be there is a cheapaer part available than HIP4081A. > >2. The second method is to use four NPN transitors to drive two PMOS >transistors (High side) and two NMOS (Low Side) transistors. >Microcontroller will provide the PWM pulses to control the 2N2222 >transistors. You can find the diagram at the following link. > >http://a.imageshack.us/img39/3520/201115.jpg > >I am thinking of using 2N2222A to drive two (IRF540N) but unable to >find the PMOS equivalent of IRF540 N. Any suggestions!! Do I need them >of the same ratings? > >Please also suggest that H - bridge driver approach is the better >approach or the NPN transistors driving the PMOS and NMOS transistors >is the good approach. I heard that the NPN driving the PMOS and NMOS >is the most efficient way, if yes than how? > >Would 2N222 be able to charge the MOSFETS quickly as HIP4081A. What >parameters should I consider before I choose the microcontroller. > >This is not a home work. :) > >Thanks >Sarah One conservative way to do this is to use fast isolated mosfet drivers, like the Avago parts maybe, and power them from cheap dc/dc converters. John
From: CIC on 5 Aug 2010 22:33
On Thu, 5 Aug 2010 17:33:56 -0700 (PDT), sarah kent <sarah6541(a)gmail.com> wrote: >On Aug 5, 7:09�pm, "Tim Williams" <tmoran...(a)charter.net> wrote: >> "sarah kent" <sarah6...(a)gmail.com> wrote in message >> >> news:afad00db-3e31-493f-bd1e-7650e7abae39(a)k19g2000yqc.googlegroups.com... >> >> > Hello All, >> >> > I am tring to generate a square wave of 100KHz and 200 volts peak to >> > peak across a resistor via H- bridge. The current could go upto 30A. >> >> AC only, no DC? �Variable duty cycle? �If so, what kind (balanced ala >> TL494 or differential ala class D audio)? >> >> Especially if the supply is line-operated (maybe this won't be an option >> for your load, I don't have a clue), I like to drive AC-only, balanced-PWM >> loads with a gate drive transformer. �This can be driven directly from a >> TL598 (or UC3525, or...), or your choice of gate driver (as long as it's >> not a complementary emitter follower type). >> >> > I am looking into two following ways to drive the NMOS ( four NMOS >> > transistors ) H - bridge. >> >> > 1. >> >> > a. Using H bridge Drivers HIP4081A. I tried to look for the >> > replacement of HIP4081A but only found A4940 from Allegro microsystems >> > which a little slower than the HIP part regarding rise and fall time. >> >> Do you have a spec for how fast you need to run? �100ns is fine at 100kHz, >> you'll most likely burn more power in conduction than switching. �Anything >> faster is a bonus, but not particularly useful (and could be dangerous, >> due to higher dI/dt forcing improved layout!). >> >> > According to my understanding the Driver chip has to charge the input >> > capacitance of the transistors. I am planning to use NMOS transistor >> > (IRF540). >> >> Whaaa? �Did you read the Vds(max) on that!? �200Vp-p needs a 100V power >> supply. �That means >150V transistors! >> >> > So, according to HIP 4081A data sheet trise = 10nsec at C= 1000pF and >> > if power supply = 50Volts (60% of 50V = 30volts) �, So, I calculated >> > (1000pF x 30V) / 10nsec = 3 Amp. >> >> > The gate to source charging capacitance of IRF540 is 14nC; So, the >> > charging time would be >> >> > (14nC x 30 V) / 3 = 140nsecs. Are my calculations accurate and in >> > right direction? >> >> No, C == A.s, so 14nAs * 30V = 420nVAs == nJ (energy). �Divide by amps >> gets you Vs, which is flux, not time. >> >> Since C == A.s, 14nC / 3A = 4.67ns. �This is less than the rated t_r so it >> will be chip-limited, not capacitance-limited. >> >> > Which proves that the A4940 is a slower part. But how will it effect >> > the voltage waveform across the resistive load. I meant to say what >> > would be the difference between the two waveforms generated by two >> > different driver chips. >> >> Likely the HIP is faster. �You'd use it if you needed to drive >> particularly large FETs particularly fast. �If you don't need the speed, >> don't put down the money for it. �A regular IR2112 is enough for mere >> IRF540s at 100kHz. �Well, a little sluggish for 100k, more like 50k for >> best results, but still not bad. >> >> > 2. The second method is to use four NPN transitors to drive two PMOS >> > transistors (High side) and two NMOS (Low Side) transistors. >> >> No. �Check Vgs(max). �Complementary MOS is impossible over 20V supply >> without extra circuitry, which adds enough complexity that you are better >> off with a driver chip and NMOS (which work better anyway). >> >> > Microcontroller will provide the PWM pulses to control the 2N2222 >> > transistors. You can find the diagram at the following link. >> >> >http://a.imageshack.us/img39/3520/201115.jpg >> >> > I am thinking of using 2N2222A to drive two (IRF540N) but unable to >> > find the PMOS equivalent of IRF540 N. Any suggestions!! Do I need them >> > of the same ratings? >> >> > Please also suggest that H - bridge driver approach is the better >> > approach or the NPN transistors driving the PMOS and NMOS transistors >> > is the good approach. I heard that the NPN driving the PMOS and NMOS >> > is the most efficient way, if yes than how? >> >> > Would 2N222 be able to charge the MOSFETS quickly as HIP4081A. >> >> Nope: >> >> 2N222 >> Low Power, General Purpose, Ge, PNP, 70mW, 15V, 12V, 70mA, 85>C, 400KHz, >> 70, 20T, RCA, TO1 >> >> Neato, it's germanium, 400kHz fT. �:^) >> >> Typoes aside, forget 2N2222 anyway. �Like 2N3055 and LM741, it is ancient >> and best left forgotten, thrown to the gutter, on the road of progress. >> 2N4401/03 are quite reasonable substitutes, and there are numerous others >> with even better performance if you insist on rolling your own gate drive. >> ZTX651 comes to mind, it's even smaller than 2N4401 yet drives 3A peak >> quite easily. �TC4420 and similar are quite popular for big jobs (6A peak, >> good for monster IGBTs). >> >> Tim >> >> -- >> Deep Friar: a very philosophical monk. >> Website:http://webpages.charter.net/dawill/tmoranwms > >Hi, > >Thanks for the reply. > >I have following questions > >1. Why complementary MOSFET scheme can not work with power supply >greater than 20 Volts? >2. Is there a way that I can generate the sine wave of 200 volts peak >to peak at 100KHz with out using H bridge driver or four MOSFETS? > > >Sarah 1. Yes the complementary MOSFET's can work with voltages above 20V, just need to drive them right. 2. You can use an wide bandwidth liner amplifier and a signal generator. Some amps already have output transformers with various taps so you can get different output voltages. You probably can rent one amp for about $1500/mo. |