Tahmid said:
There is nothing special about the circuit, only some layout considerations to get rid of negative transients on Vs (ground plane and gentle switching node copper area on the opposite side).
Remember that the inputs are edge triggered, so if they were high before the shutdown pin went low, the outpus will remain low until HIN or LIN are pulled low and high again. Note that the bootstrap capacitor has to be charged too before the high side can operate. This results in a funny startup behaviour in most cases, unless you have a microcontroller to produce the signals in the right sequence.
Big enough to keep the high side powered during the longest time it is expected to be turned on. Worst case quiescent current of the high side driver is 1mA. Do the math...
Hint: delta(V)=i*t/C
Hint: delta(V)=i*t/C
Eva,
When I said size, I meant the appropriate value of the bootstrap capacitor.
I do not understand all these formulas. If I did, I would not have asked you and luka. I could have done it myself.
When I said size, I meant the appropriate value of the bootstrap capacitor.
I do not understand all these formulas. If I did, I would not have asked you and luka. I could have done it myself.
Capacitor value is usually application specific, and you don't even seem to know for how long the capacitor has to provide power to the high side driver in your application. You won't be able to design good reliable electronics until you understand some basic math and formulas.
How could someone not understanding "delta(V)=i*t/C" design a SMPS?
How could someone not understanding "delta(V)=i*t/C" design a SMPS?
Have you read the app notes regarding the 2110s? No offense, but from the questions you are asking smps design seems out of your league.
No offence eiter...
For exampe, if you want a capacitor whose voltage drops by 1V after 1mA load is applied during 10ms :
delta(V)= 1V
i = .001A
t = .01s
V=i*t/C --> C=i*t/V --> C=.001*.01/1 = 10uF
For exampe, if you want a capacitor whose voltage drops by 1V after 1mA load is applied during 10ms :
delta(V)= 1V
i = .001A
t = .01s
V=i*t/C --> C=i*t/V --> C=.001*.01/1 = 10uF
Yes, I have read and studied them several times, maybe more than you.
I asked all the questions because the circuits and design ideas given in the application notes were not working properly.
I just finished testing of my new circuit and it was working properly. It was working not according to the circuit provided by IR in application notes, but with some modifications.
Eva,
I asked your help regarding the value of the bootstrap capacitor, because you have mentioned that you have made many circuits with IR2110, but you have shown a very negative and offensive attitude. This is not right.
Your calculation shows that the bootstrap capacitor is 10uF. In the application notes, IR suggested 0.47uF. But, for different power levels they did not mention changing the bootstrap capacitor value. Which one is correct? Your formula or IR?
I have tested with different values from 0.47uF to 100uF and find that Luka is correct. The overall performance remains same, irrespective of the value of the bootstrap capacitor. This is what Luka said earlier. So, here, I do not think your formula stands. I may not know these formulas, being a student of standard VIII, but I do have practical experience and working hard to acquire required knowledge with the help of knowledgeable and senior members like you, luka and switchmodepower and others.
I asked your help regarding the value of the bootstrap capacitor, because you have mentioned that you have made many circuits with IR2110, but you have shown a very negative and offensive attitude. This is not right.
Your calculation shows that the bootstrap capacitor is 10uF. In the application notes, IR suggested 0.47uF. But, for different power levels they did not mention changing the bootstrap capacitor value. Which one is correct? Your formula or IR?
I have tested with different values from 0.47uF to 100uF and find that Luka is correct. The overall performance remains same, irrespective of the value of the bootstrap capacitor. This is what Luka said earlier. So, here, I do not think your formula stands. I may not know these formulas, being a student of standard VIII, but I do have practical experience and working hard to acquire required knowledge with the help of knowledgeable and senior members like you, luka and switchmodepower and others.
Tahmid,
Don't always bother about application notes of different companies. Study them carefully and apply the appropriate portion in the circuit. IR2110 don't perform properly all the time- maybe due to the difference of qualities. I had lot of headache with those. I have tested with different values of Bootstrapping capacitors and the circuit works and you can use both polar and non polar capacitors. However,if you are not satisfied with IR 2110, You may try TLP 250 or L6385 which I find very useful.
Life is full of trade off. Do not be disheartened. Future is yours.
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Ideas are money if you can use it on ground - not only in Theory.
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Don't always bother about application notes of different companies. Study them carefully and apply the appropriate portion in the circuit. IR2110 don't perform properly all the time- maybe due to the difference of qualities. I had lot of headache with those. I have tested with different values of Bootstrapping capacitors and the circuit works and you can use both polar and non polar capacitors. However,if you are not satisfied with IR 2110, You may try TLP 250 or L6385 which I find very useful.
Life is full of trade off. Do not be disheartened. Future is yours.
-------------------------------------------------------------------------------------------
Ideas are money if you can use it on ground - not only in Theory.
------------------------------------------------------------------------------------------
Tahmid said:
ah...Now I said no offense.
You can this formula in this instance.
C=(Qgate)/deltaV
Where Qgate is the gate charge for the mosfet. You'll find that 0.1uF will most likely work in most applications.
ps.- The values that Eva posted when just for an example and don't reflect this design.
In an audio amplifier you want the high side switch to remain powered even during hard clipping, that's why a large capacitor value is recommended. Since gate charge and discharge times (and dead time) are strongly dependent on the magnitude of the high side supply voltage, a high capacitor value like 100uF or more reduces distortion. Charging this capacitor at startup is troublesome and requires some special considerations, though.
In other applications like sinewave inverters, distortion is not critical and only slight clipping may happen, so 4.7uF is usually more than enough.
In a plain SMPS applications with a HF transformer or a fluorescent lamp as a load, the bootstrap capacitor is gently recharged on every cycle so values as small as 100nF are ok.
If you follow the "any value is ok" advice, you will be contributing to worsen the already low quality and reliability of the electronics that is being designed in your country and other places. This is the wrong advice.
There is no way other than learning some math and formulas. For example, I'm finishing a very high performance commercial 2500W sinewave inverter and I'm flooded with numbers, formulas and small computer programs to calculate optimum values and timings for everything. It would take years to arrive at the same results by trial and error. I'm not an EE, I learn everything by myself.
In other applications like sinewave inverters, distortion is not critical and only slight clipping may happen, so 4.7uF is usually more than enough.
In a plain SMPS applications with a HF transformer or a fluorescent lamp as a load, the bootstrap capacitor is gently recharged on every cycle so values as small as 100nF are ok.
If you follow the "any value is ok" advice, you will be contributing to worsen the already low quality and reliability of the electronics that is being designed in your country and other places. This is the wrong advice.
There is no way other than learning some math and formulas. For example, I'm finishing a very high performance commercial 2500W sinewave inverter and I'm flooded with numbers, formulas and small computer programs to calculate optimum values and timings for everything. It would take years to arrive at the same results by trial and error. I'm not an EE, I learn everything by myself.
EVA and FORMULA,
I ardently follow the writings of EVA as his/her replies always full of lot of Theory and Formula which sometimes reminds me regarding my class room in EE Course. I try to learn all the times. Yesterday, I came across the deliberations between Tahmid and EVA. Tahmid is a school going kid showing interest in Electronics and asked help from EVA and in reply EVA told that country like ours are responsible for making bad quality Electronics. Since he/she talked bad about my country, I think I should say something in reply.
Tahmid wanted to know from EVA what should be the size of the Boot strapping Capacitor in IR2110 while making a full bridge circuit for converting 220v dc to 220v ac in a small circuit.
Answer should be as simple as follows: IR2110 can be utilized for using upto 15kw rating and for Virtual Ground in High side Mosfets, IR shown in their application note that Boot strapping Capacitors can be of 0.47 uF. It can be polar or non polar and practically it was seen that capacitors can be of 1000 uF even.
But EVA's answers were as follows:
Does his/her replies bear any fruitful answer for the kid?
As usual, EVA is non committal and beating around the bush. He/She is confused and make others thorough confused also.
SHE / HE WANTS TO USE CANNON TO KILL MOSQUITO.
As my knowledge goes no International organization has given EVA the sole responsibility to monitor the quality of electronics products in different countries including my country. One should not speak bad of another country because everybody loves his country. I will never say anything bad about Spain, which is a beautiful country and Real Madrid is my favorite team. But sometimes I feel bad as it should excell in other fields like electronics as they have excelled in Bull fight and Football.
The kid wanted to know the value of Bootstrapping capacitors in IR2110. He did not want to know whether you are an EE or not or with what you are busy and he also did not want to know the maths, formulas, softwares required for making 2500W sine wave inverter. Why to bother him with negative and self propagating reply? This forum is for encouraging others not discouraging. Help others if you want to or don't if you don't want. The kid will learn all the critical theory, formula and critical softwares with the passage of time and also in the classroom of EE course in any reputed University. Now help the kids/novices to attain and maintain interest by providing them concrete answers.
Becoming a Bookworm and Theory biased may not always bring good result to the practical field. Interaction between Theory and Practical field is always necessary to create any thing good and simple and concrete answer is always enviable in this digital world where the whole system is based on simple and concrete, 0 or 1 -- no place for ambiguity. No offense.
Thanks.
I ardently follow the writings of EVA as his/her replies always full of lot of Theory and Formula which sometimes reminds me regarding my class room in EE Course. I try to learn all the times. Yesterday, I came across the deliberations between Tahmid and EVA. Tahmid is a school going kid showing interest in Electronics and asked help from EVA and in reply EVA told that country like ours are responsible for making bad quality Electronics. Since he/she talked bad about my country, I think I should say something in reply.
Tahmid wanted to know from EVA what should be the size of the Boot strapping Capacitor in IR2110 while making a full bridge circuit for converting 220v dc to 220v ac in a small circuit.
Answer should be as simple as follows: IR2110 can be utilized for using upto 15kw rating and for Virtual Ground in High side Mosfets, IR shown in their application note that Boot strapping Capacitors can be of 0.47 uF. It can be polar or non polar and practically it was seen that capacitors can be of 1000 uF even.
But EVA's answers were as follows:
Does his/her replies bear any fruitful answer for the kid?
As usual, EVA is non committal and beating around the bush. He/She is confused and make others thorough confused also.
SHE / HE WANTS TO USE CANNON TO KILL MOSQUITO.
As my knowledge goes no International organization has given EVA the sole responsibility to monitor the quality of electronics products in different countries including my country. One should not speak bad of another country because everybody loves his country. I will never say anything bad about Spain, which is a beautiful country and Real Madrid is my favorite team. But sometimes I feel bad as it should excell in other fields like electronics as they have excelled in Bull fight and Football.
The kid wanted to know the value of Bootstrapping capacitors in IR2110. He did not want to know whether you are an EE or not or with what you are busy and he also did not want to know the maths, formulas, softwares required for making 2500W sine wave inverter. Why to bother him with negative and self propagating reply? This forum is for encouraging others not discouraging. Help others if you want to or don't if you don't want. The kid will learn all the critical theory, formula and critical softwares with the passage of time and also in the classroom of EE course in any reputed University. Now help the kids/novices to attain and maintain interest by providing them concrete answers.
Becoming a Bookworm and Theory biased may not always bring good result to the practical field. Interaction between Theory and Practical field is always necessary to create any thing good and simple and concrete answer is always enviable in this digital world where the whole system is based on simple and concrete, 0 or 1 -- no place for ambiguity. No offense.
Thanks.
xyz9915,
Sorry for hijacking your thread and using it for our purpose. What is your progress? Hope to help you if you require. Try - learn- mistake-learn- try. If you don't have the capability to do mistake- you cannot earn the laurels of success.
With thanks.
Sorry for hijacking your thread and using it for our purpose. What is your progress? Hope to help you if you require. Try - learn- mistake-learn- try. If you don't have the capability to do mistake- you cannot earn the laurels of success.
With thanks.
Thanks for encourage. I am still in the development stage but I hope that I will make it in this week.
A silly doubt
I am a newbie to this forum and I did a few posts in another thread. Electronics is not my profession, but I used to do some hobby circuits.
I recently bought two 15A car battery charger thru ebay. They were getting extremely hot even on no load and one blew up the fuse and MOSFETs while on 4A drain for 30 minutes. Obviously there was a design fault with those circuits
I then bought a cheap ATX PSU and modified its 12V to get 13.7 volt. Its 12V rail is rated 17A, but I am sure i can get more if rectifier diodes of proper rating used.
The initial cicuit I bought , I think, was half bridge topology with 2 powerful MOSFETS. But the ATX PSU seems to be a forward converter with just 1 MOSFET and a smaller transfermer and a relatively simple circuit, but still rated 400W. That mosfet has a smaller heatsink still doesn't get as hot as the rectifier diode. It gives a rock solid output current with no voltage drop even at 15A. My only problem was to build a current limiter (as I am sure it will deliver over 40A if output is shorted and blow up) which I am doing now.
My question is (please remember I am ignorant in this) if that simple ATX circuit with single mosfet can deliver this solid performance with minimal heat , why do we need those complex topologies for a simple 12V battery charger?
I am a newbie to this forum and I did a few posts in another thread. Electronics is not my profession, but I used to do some hobby circuits.
I recently bought two 15A car battery charger thru ebay. They were getting extremely hot even on no load and one blew up the fuse and MOSFETs while on 4A drain for 30 minutes. Obviously there was a design fault with those circuits
I then bought a cheap ATX PSU and modified its 12V to get 13.7 volt. Its 12V rail is rated 17A, but I am sure i can get more if rectifier diodes of proper rating used.
The initial cicuit I bought , I think, was half bridge topology with 2 powerful MOSFETS. But the ATX PSU seems to be a forward converter with just 1 MOSFET and a smaller transfermer and a relatively simple circuit, but still rated 400W. That mosfet has a smaller heatsink still doesn't get as hot as the rectifier diode. It gives a rock solid output current with no voltage drop even at 15A. My only problem was to build a current limiter (as I am sure it will deliver over 40A if output is shorted and blow up) which I am doing now.
My question is (please remember I am ignorant in this) if that simple ATX circuit with single mosfet can deliver this solid performance with minimal heat , why do we need those complex topologies for a simple 12V battery charger?
Complex? It doesn't need to be, it is just what you want circuit to do, ATX has only one job to do, regulate output, over/under voltage is standard...some have overload protection, and so on...and this way you get "complex" circuits. And which topologies are complex to use for 12v smps?
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