am doing an smps. i would like if you have the ovecurrent protection for your schema please post it. Thanx in advance steve
yes i have fuses . but just wondering if these protection part of the scheme can be added to your circuit as an overcurrent protection. the web adress for the forums in google translate mode
Google Translate
Google Translate
Google Translate
Google Translate
Attachments
we sure you can add overcurrent shutdown, depends... if you expect overcurrent, then put that in, if not, fuses are enough
in case of driving two channel amplifier with two ohms each,the amp is classD and uses 75-0-75vlts will the smps withstand that load without affecting the irfp460s mosfets? Or do i have to bridge the smps so that it can handle? And will it work for long without the current limiter protection circuit?
you could make 2 of them, each for is own channel
will your amp even work at those voltages and 2R loads?
will your amp even work at those voltages and 2R loads?
i hope so because it is a class d and class d are known for their efficiency . many class ab's and h use greater voltages and can do 2ohms comfortably since class d are so efficient i hope it will .we are continuing on the forum about the amps design pls do join us because your expertise could help a lot steve
http://www.diyaudio.com/forums/clas...200-watts-using-2-mosfets-30.html#post2264454
http://www.diyaudio.com/forums/clas...200-watts-using-2-mosfets-30.html#post2264454
More power
If you are refering to Luka's supply change two components and increase fsw to 75kHz and if you have room add 2 windings to each secondary of the ETD-44 bobbin,if not move to the ETD49 core set and use 75kHz fsw 28 turns primary and 10 turns secondary ,with this you should get about 80 VDC 2 ohm load would need to be tested,you might need to change the fsw to 100kHz leave windings the same and consider IGBT for switch.
chas1
ps current limit is a easy with SG3525,check datasheet.If you need circuit let me know.And I would move to FB... fsw is transformer frequency not controller
If you are refering to Luka's supply change two components and increase fsw to 75kHz and if you have room add 2 windings to each secondary of the ETD-44 bobbin,if not move to the ETD49 core set and use 75kHz fsw 28 turns primary and 10 turns secondary ,with this you should get about 80 VDC 2 ohm load would need to be tested,you might need to change the fsw to 100kHz leave windings the same and consider IGBT for switch.
chas1
ps current limit is a easy with SG3525,check datasheet.If you need circuit let me know.And I would move to FB... fsw is transformer frequency not controller
i really need the protection scheme because i,ve seen them working excellent in car amplifiers if you over load or shot the amp it just turns off instead of burning the amp or the power supply. if you can include led on the scheme i would appreciate. BTW what will i need to change is it ct or rt ?? i would rather stick with the mosfet because igbt's are like very hard to find them here . but the irfp460 and irfp450 are plenty and affordable many thanks in advance steve.
it uses a transfomer to detect. what about the scheme your protection scheme . thanks in advance
steve
steve
current xfmr
I use a current transformer with the proper burden resistor for that transformer feeding a bridge made up of 1n4148 driving a resistor to set volts per amp and filtered by cap ,a voltage divider with a variable resistor to set limit.The calibration is for every amp of primary current I get 2volts out.
I use a current transformer with the proper burden resistor for that transformer feeding a bridge made up of 1n4148 driving a resistor to set volts per amp and filtered by cap ,a voltage divider with a variable resistor to set limit.The calibration is for every amp of primary current I get 2volts out.
Hello guys,
To safely shutdown the smps you have to short the SoftStart cap. After shorting it the smps will go to 0 duty cicle. when the short is removed the cap will start to charge and the duty cicle will gradualy start from 0 to 49%.
i used this method and it is great. the smps will restart over and over again until the overcurent condition passes.
you have to make a overcurent protection that will trigger a small mosfet witch shorts pin CSS of SG3525 to GND.
best regards,
Savu Silviu
To safely shutdown the smps you have to short the SoftStart cap. After shorting it the smps will go to 0 duty cicle. when the short is removed the cap will start to charge and the duty cicle will gradualy start from 0 to 49%.
i used this method and it is great. the smps will restart over and over again until the overcurent condition passes.
you have to make a overcurent protection that will trigger a small mosfet witch shorts pin CSS of SG3525 to GND.
best regards,
Savu Silviu
well you don't have to do that yourself, sg has circuit for that already inside, you just have to apply signal to the shutdown pin on sg and it will turn of
shutdown pin of SG3525
Luka
Glad to see you monitor our long thread,Luka is right the datasheet describes the shutdown in detail.A voltage level greater than 1.4 volts at pin 10 should shut the supply down and discharge and restart the SS again but you still need a circuit to supply the 1.4 volts low power a resistor will work but at high power levels a current transformer is the best way in mho.
Luka
Glad to see you monitor our long thread,Luka is right the datasheet describes the shutdown in detail.A voltage level greater than 1.4 volts at pin 10 should shut the supply down and discharge and restart the SS again but you still need a circuit to supply the 1.4 volts low power a resistor will work but at high power levels a current transformer is the best way in mho.
Hey Chas,
I sure do, every post. I will need it soon for lil project of my, this time I will make it as it was intended to be, regulation and all, won't be full bridge since I don't need that kinda power levels. maybe I'll even try current sensing for shut down while am at it.
I sure do, every post. I will need it soon for lil project of my, this time I will make it as it was intended to be, regulation and all, won't be full bridge since I don't need that kinda power levels. maybe I'll even try current sensing for shut down while am at it.
hello guys,
i understand the function of the shutdown pin but the idea is that a 0 ohm resistor (short) wil discharge the cap faster than a 5k resistor. in case of a short impulse from the protect circuitry if the cap is not fully discharged it will start to charge from where it was left after the short pulse from the overcurent prot. in this case the inrush current would be higher.
best regards,
savu silviu
i understand the function of the shutdown pin but the idea is that a 0 ohm resistor (short) wil discharge the cap faster than a 5k resistor. in case of a short impulse from the protect circuitry if the cap is not fully discharged it will start to charge from where it was left after the short pulse from the overcurent prot. in this case the inrush current would be higher.
best regards,
savu silviu
its not intended to turn it off right away, it lowers duty, kinda like you would have current limit, this is for short sd pulses, for longer its the same, but in the end it will turn off completly