SMPS 2 x 50V 350W for Audio Power Amplifiers

This article will illustrate a simple procedure to devise an unregulated 50V switching SMPS symmetric power supply of 350W. This unit can be substituted with the standard audio amplifier power supply to reduce expense and also the weight. The proposed power supply works as a half-bridge with no regulation.

Written and Submitted by: Dhrubajyoti Biswas

Mosfets as Power Devices


My power supply relies on two N MOSFET and run by IR2153 integrated circuit. The IR2153 is powered by a power resistor of 27K 6W. The ripple at full load is recorded below 2V.

The use of Zener diode (15V) ensures voltage stabilization and the operating frequency is set to 50 kHz (approx.).

At the point of the input, I have placed a thermistor to force a check on the peak current when the capacitor is getting charged.

This same phenomenon can be found in AT/ATX power supply unit of a computer. Moreover, to ensure low leakage inductance and full voltage output, the first half of the primary is wounded in 20 turns followed by the secondary wound.

Also to assure safety in the system, do be sure to connect the output (center tap 0V) to the earth.

Chokes for Filtering RF


The chokes used in the design will facilitate removal of RF output ripple. The number of turns and the core which is found in PC supply is not a critical factor.

Additionally, the 6k8 resistors at the output section is used to discharge capacitors after it is switched off and this way it helps to prevent the voltage increase during no load.

The proposed Switched power supply 2x 50V 350W operates in single switch forward topology. It has an operating frequency of 80-90 kHz and has IRF2153 control circuit which is very much similar to that of US3842. However, the duty cycle is lesser and is limited to 50%.

Rewinding an ATX Trafo


The Tr1 transformer was devised by rewinding the SMPS ATX transformer and its primary inductance is 6.4 mH (approx.).

The core of the system has no air gap and the primary inductance is further broken in two parts: The first half is the wind and the second is the winding.

Moreover, it is also feasible to deploy the original primary bottom half without rewinding. This type of power supply aptly suits for power amplifier applications.

If required it may be also safeguarded against overload or short circuit and the voltage of the output could be stabilized. The Feedback of the system may be enabled through the help of optocoupler.

It is important to note that in regard to 350W power, care should be taken that in the conductive state the typical resistance should not cross more than 0.8R. MOSFET can also be used to lower the point of resistance.

Interestingly, the smaller the resistance better is with the system.

The voltage tolerance is in the range of 900-1000V. In the worst case scenario 800V can be used. Considering this, the best MOSFET I found was SPP17N80C3 or 900V IGBTs.

Circuit Diagram




 

Coil Winding Details:


The main transformer which can be seen integrated with the mosfets may be wound on a standard 90 by 140mm^2 ferrite bobbin core assembly.

The primary side winding consists of  40 turns of 0.6mm super enameled copper wire.

Remember to stop after 20 turns, put an insulation layer with an insulation tape and wind the secondary winding, once the secondary is wound, insulate it again and continue with the remaining 20 turns over it.

Meaning the secondary winding gets sandwiched between the primary 20 + 20 turns.

The center tap of this 20+20 may be connected with the body of the SMPS for an improved stabilization and cleaner outputs in terms of ripples or buzzing interferences.

The secondary consists of a center tapped 14 x 2nos turns made by winding 0.6mm super enameled copper wire.

The input and output filter coils may be wound on ferrite torroidal cores. The paired winding must be wound on the same individual torroidal cores using 0.6mm super enameled copper wire with 25 turns on each arm of the relevant supply terminals.

Update:

The above design 350 watt SMPS circuit was further improved by one of the dedicated members of this website Mr. Ike Mhlanga.The complete schematic of the same can be witnessed in the following figure:



 

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Comments

style said…
Sir,
Above circuit can be use for audio Amplifier which u have given . in this article the difficult part is transformer. Is it possible for you give a separate topic on this with picture
Thanks and regards
Swagatam said…
style, there's nothing difficult in it if you read and follow the instructions carefully, if you have problems you can always ask me for further help....
style said…
Thanks a lot sir..
You have any topic related to transformer making . I mean to say like calculation of E and I core calculations, bobbins size calculation, what size of gauge wire to be use. So that I can make a different voltage and wattage of transformers.
Thanks and regards
Swagatam said…
style, presently I do not have all the info regarding ferrite transformer designing, once I collect it will surely update them in this blog...
style said…
Dear sir ,
Sir I want power supply 50-0-50. /12 amps. Wat would be the gauge of secondary coil and number of turn
Thanks and regards
style said…
Dear sir
What is the primary frequency because one place its mentioned 50khz and in another place 80- 90 kHz
Second thing what is the primary current to the transformer
Thanks and Regards
Swagatam said…
Dear style, it doesn't make much of a difference whether it's 50 khz or 80 khz, for precise answers you can calculate it yourself by referring to the IC datasheet and by inserting the 47k and 300pF in the given formula
style said…
Dear Sir
For making PCB what specification i have to tell to shop . i want to make 1000 watt stereo
I want good quality COPPER BOARD
Regards
Swagatam said…
Dear style today all standard PCBs are made on glass epoxy base, so presently it's the best both quality wise and cost wise.
Rikenz Lalar said…
What if I use a ferrite EDT49, whether the number of turns on the primary and secondary side as you say?
And if the switching frequency is 90kHz, if there is a change in the circuit or component changes?
Swagatam said…
you can use any EE core as long as it accommodates the winding comfortably it'll be fine.
you'll have tweak and adjust the 47k/300pf values for getting the desired frequency with some trial and error.
Rahul anymation said…
hello sir,instead of ferrite core can I use iron core which is used in transformer ?
Swagatam said…
hello Rahul, iron core will not do, it has to be strictly ferrite
Dear sir.. what is the size of ferrite core...
Swagatam said…
a 15mm EE core should do the job, the size actually does not matter as long as it accommodates the winding comfortably.
style said…
Sir I have one system which is operational on 110volt 60 hz.. What can I do to make its operational,as we have 220V 50hz.. Help me sir
Swagatam said…
you may have to buy a VFD or build yourself one as given here:

https://homemade-circuits.com/2013/09/single-phase-variable-frequency-drive.html

style said…
Sir, System is 120 Volt and 60 hz. Can it be operated with 120 volt 50hz. The system power supply is smps based . does it effect the systems any way. And Sir , power rating is 500 watts. Can I use this give circuit for this.

Thanks n regard
Swagatam said…
Style, in the previous link of a VFD circuit, you can adjust and set the output to 120V 60 Hz or to any desired level as per the load specs, therefore according to me it would be suitable for your application too.

the power is related to the mosfets which can be upgraded as per the requirements.
style said…
Sir,
What will be effect on system ( Panasonic amplifier 7.1) if we give 50hz instead of 60 hz. Power supply is smps based.

2. The source of mosfet be given 110volt .but how can I get 110 volts .
Please help me
Swagatam said…
Hi Style,

frequency change will not make any difference to an SMPs, for getting 110v you can eliminate the center tap of the above circuit and acquire the required 110 V from it.
Richard Lover said…
please boss i need your help now, i want you show me how to build power inverter, if you teach i will be happy for you?
Swagatam said…
you can go through the following article, it has most of the info regarding the subject:

https://homemade-circuits.com/2013/03/how-to-design-inverter-basic-circuit.html
chinmoy1955 said…
Dear Swagatam,
I would like to sympathize with style for his difficulties in understanding the transformer winding details. Though the idea behind this article is very innovative and commendable, the narration is very sloppy and written in poor English with a lot of grammatical errors. I am not criticizing your post, but I suggest a more detailed proof reading of technical articles for a better presentation. For an experienced hand it is okay, but for a less initiated person or a novice, it can be very confusing. A few drawings or pictures would have made a lot of difference, as suggested by style.

I congratulate you on the excellent articles you have written in your blog, keep it up.

Regards
Swagatam said…
Dear Chinmoy,

yes the article is a rephrased version and may have a few errors since it was written by a person with only general electronic knowledge.

the circuit actually has nothing complex in it.
the IC is a half bridge IC which generates a push pull output for the connected mosfets, which in turn switch in a full-bridge manner due to the involved dual AC input configuration.

this results in an efficient induction across the output winding

if you can go through the datasheet of the IC, you'll be able to get a better picture of its functioning details
nhark alajid said…
Sir,do you have a layout for this schematic sir?
Swagatam said…
sorry, no PCB layout for this...
Raymond Michael said…
Thanks for this sir, though i saw it several days ago;the reason why i did't consider it much is all about the IC, i think i will a serious problem to find it in my local shop here in Tanzania, is there any other way around without involving ic?
Thanks though sir, thanks
Swagatam said…
Raymonds, unfortunately there's no easy alternative to the above IC because it's a specialized half bridge driver IC...and does not depend on a center tap trafo, rather uses a two wire trafo for an efficient performance.
Naufan said…
Hi Swagatam...
In my Country, IR2153 IC is still rare. Because IR2153 IC is for a PWM Generator, can i change the IC to LM555 or CD4047?
Swagatam said…
Hi Naufan,

LM555 or CD4047 will not work, because these are not equipped with high-side drivers.....these are just ordinary oscillators, while IR2153 is a specialized half-bridge driver IC...
nitin gondliya said…
hy,,,swagatam..u r genius
can i use troidal core ring.?? plzz give me ring size.
thx in advance..
Swagatam said…
Hi Nitin, a torroidal core will work, but might require an entirely different winding data which I am not sure how to calculate....you can try it and find the most optimal results with some experimentation.
nitin gondliya said…
thx 4 your adwise..i will try n post result.
Dear Swagatam, I would like to build a regulated smps for my audio amplifier which will be capable of around 400 watts, and having a voltage of 50-0-50. If possible using the TL494 or similar device. I have quite a few ATX power supplies at hand and can salvage parts from them.
Thanks in advance
Swagatam said…
Dear Silvio, you can try the following inverter design, just replace its trafo with the a ferrite trafo which is discussed in the above article for obtaining the intended results:

https://homemade-circuits.com/2014/06/smps-2-x-50v-350w-circuit-for-audio.html
Sorry for misleading you I was referring to a mains operated power supply.
Swagatam said…
yes I understood, actually you can configure the supply pins of the TL494 in the similar way to the above shown design. that is connect the positive pin of the TL494 just as pin#1 of the IR2153 is configured...this might just work
Swagatam said…
I appreciate your interest, however I am sorry, that would be difficult at the moment due to lack of time!
Hi!
I have a question about the two capacitors of 1000uF (200V). Can I use two 470uF (200V) instead of two 1000uF (200V)?
Swagatam said…
lower value will reduce the current at the output....the value of these caps determines the output current
With two 470uF I can get 4A?
Swagatam said…
it will need to be calculated, most probably it may be possible to get 4A
Hi!
I thought of doing so circuit (with these components):
substituting:
  the first capacitors 0.470uF (400V) with 0.100uF (400V)
  1000uF capacitors (200V) with 470uF (200V)
  The 2.2uF capacitor (400V) with 0.5 uF (400V)
Potrebe work?
To me I need a single output of 50V 3-4A and no more than 200W.
You can do with these changes?
THANK YOU!
Swagatam said…
It should be exactly as shown in the diagram, other values could produce inefficient results
Instead of IRFP460 can I use IRFP260N?
Swagatam said…
please check their I and V specifications, if they match then you can interchange the two.
roberto capua said…
Hello Swagatam,

I'm new here and I'm not sure if you have already posted the circuit that I'm looking for. I need a power supply/inverter/smps with 12VDC input (from car battery) with an output of +50VDC & -50VDC at least 10ampere current capacity or more. Much better if the circuit is configured in SMPS.
Thank you and more power to you....
Swagatam said…
Hi Roberto, you can try the above explained concept with some modifications.

Instead of the mains you can apply 12V to the left hand side circuit...and you will need to modify the primary/secondary winding of the transformer.

For the primary side you could try around 5 turns and for the secondary 20 + 20 turns

the turn ratio might require further analysis and modifications, since it's not calculated by me precisely
Prince Jose said…
Hello Swagatam,

My name is Prince Jose... This is a nice diagram. I want +/-90v 8A, how i can make it with you diagram, and also can i change the winding wire thickness.....
Swagatam said…
Thank you Prince,

you can certainly achieve it by tweaking the secondary winding of the transformer....the current can be increased by using more number of parallel wires across both sides
Prince Jose said…
PRINCE JOSE>
THANK YOU FOR YOU REPLY.....
I HAVE SOME MORE DOUBTS CAN YOU CLEAR THAT...

>WHAT IS THE VALUE OF 'NTC'???
>HOW I CAN CHANGE THE CIRCUIT BRIDGED??
>OR CAN I ADD EXTRA TRANSISTORS IN PARALLEL??
>CAN YOU SUGGEST ANOTHER RECTIFIER DIODE FOR OUTPUT SECTION....
Swagatam said…
The NTC value could be 5 ohm, 11mm diameter, as shown in the following article:

https://homemade-circuits.com/2013/02/using-ntc-resistor-as-surge-suppressor.html

you cannot change anything in the design, it has to be exactly as shown.

more no. of transistors won't be required if you select the two mosfets with adequate rating.

you can use any 6 amp fast recovery diodes at the output
Ike Mhlanga said…
Dear Swagatam,

I would like to use the above SMPS to power my mixer. The output would have to be +16V 0 -16V and 48V for phantom power. Could you suggest the output configuration of the output transformer in this case.

Thank you in advance.

Ike
Swagatam said…
Dear Ike, you can use the same configuration which is discussed in the article, for the 16V you can drop the output either using an optocoupler based feedback loop or a LM338 dual power supply as shown below

https://homemade-circuits.com/2015/07/dual-power-supply-3v5v6v9v1215v-with.html
Ike Mhlanga said…
Dear Swagatam,

Thank you for the feed back. I will try to implement using feedback via optocoupler. Its a more elegant way of implementing the control and self adjust to demand.

I have researched the net esp on edaboard.com and it seems the IR 2153 has no pin for voltage regulation but one for shut down ie pin 3. Could you suggesta schematic for implementing voltage control Mr Swagatam?? Thanx in advance for the help.
Swagatam said…
Thank you Ike, The shut down pin#3 itself can be used for the intended regulation, you can configure the optocoupler quite as shown in the following smps design,, or any other similar design

https://homemade-circuits.com/2014/02/220v-smps-cell-phone-charger-circuit.html

for your application the collector of the opto transistor could be integrated with the pin#3 of the IR2153
Ike Mhlanga said…
DearSwagatam,

hank you for the pearls of wisdom. I have seen another scheme which has a BC457 transistor tied to pin 3. It however is not simple. I will mess around with what you have suggested. I would however like to send you ms Eagle schematic for corrections. How do I do that??
Swagatam said…
Dear Ike, you can send it to

homemadecircuits @ gmail.com
Prince Jose said…
Sir, can I use 555 timer for pen generator and ir2111 for driving section????
Swagatam said…
Prince, No that won't be possible because 555 is not designed as a half bridge driver.
reynaldo said…
sir,, i would like to build this,, maybe you have a pcb deign for this,, tnx a lot.
Swagatam said…
sorry reynaldo, I do not have a PCB design at the moment for this...
odie santos said…
Dear Swagatam,

Very nice circuits. Is the circuits already been tested?
Can i use the Ei33 core? do i need to used gapped or ungapped core.?
And what is the size of the wire? can i use a litz wire here?
Thanks to your blog is very helpful to our newbie..

Regards,
odie
Swagatam said…
Thanks odie,

yes it is a fully tested circuit, the size of the wire is given in the article under the winding details, it is 0.6mm for both the sides, the wire should be a super enameled copper wire. yes you can use a EI33 core just make sure the winding perfectly accommodates within the bobbin....the core surfaces in contact with each other must be separated with a paper gap.
Zollee said…
Dear Swagatam!

You wrote that the center tap of the primary coil should be tied to the body. Directly or through a series capacitor? The wiring diagram is not marked. I have not seen such a solution yet in other circuits, and it is strange to me that the high-voltage coil is directly connected to the body, which, in any case, acts as a protective ground. Is not the secondary side's gnd bound to the body? I'm confused!
The value of the potentiometer in the second drawing is not indicated. How much is its resistance? The two mosfets can be IRF840?

Thank You for Your help!
Swag said…
Dear Zollee, the article was written by another author, and may be the secondary ws referred to as the primary, because the primary does not have any center tap.

the secondary is completely isolated from the primary therefore the center tap can be connected with the body to increase stability and reduce noise.

the value of the pot can be selected with the some trial and error or by referring to other similar SMPS designs.
pavan said…
hai i want to design 0-65v /3amps smps circuit .please help me
pavan said…
Hai sir , I follow your site regularly its very good . i want to design 3amps/65v output smps . Its very urgent please help me .
Swag said…
Thanks Pavan,

you can try the concept explained above and modify its parameters to achieve the required output as per your specs.
pavan said…
Thanks for your replay i need only +50v not -50v .what changes should i do . need to change transformer windings or anything
.pls explain me
Swag said…
if you remove the center tap then the negative voltage side will go.....the secondary winding turns can be decreased to get a lower value at the output
pavan said…
hello sir .pls tell me how to select a capacitor value in a circuit while designing .
Swag said…
which capacitor?
Damian PL said…
Have you pcb ?
Swag said…
sorry PCB design is not available
Edeson said…
Swagatam ! Does it require modification in circuit too, if i don't want to use center tap in secondary? Because, I don't need dual output as my purpose is to get high current for welding. I'll be increasing MOSFET's and using thicker wires (maybe parallel twisted etc).
Second thing as i understood from the description you wrote. On primary side as there are 40T so i need to wind 20T create insulation then wind secondary turns and create insulation then finally wind back remaining 20T for priminary. Which means overall i need to keep secondary between the winding of primary.
Swag said…
Hi Edeson, You can use the same circuit which is explained in the above article, and only modify the winding with higher current wires...the winding method will be also the same, the wires could be upgraded by using bifilar system where many thinner wires are used together to make the winding capable of handling more power.
and yes the secondary center tap can be removed and modified into a single winding

however please note that whatever I am saying it is with an assumption, so please proceed with the necessary cautions.
Mho said…
Morning Sir. Really educative post. I would love you to write an article on SMPS, clearly differentiating the topologies Half bridge and Push pull, including their switching waveforms. These two have got me puzzled for a while, before I finally figured it. Also, clearly differentiate between a regular synchronous buck converter and the half bridge, in terms of their switching waveform.
Finally, could you also explain more about the feedback for this system, since w know the chip has no provision for feedback. What is the rationale behind using the shut down pin to achieve a regulated output?
Thanks a million for your answers, I read you blog daily, and its been most educating.
Swag said…
Thank you Mho, I had thought of presenting one such article by referring to the details from the following document

https://www.onsemi.com/pub/Collateral/SMPSRM-D.PDF

But I felt it lengthy and stopped the work due to lack of time, but in future I may consider introducing it in my website.

the shut down pin can be used for disabling the output as soon as an over-voltage is detected at the output, this situation will try to shut down the output which will cause an instant drop in the output voltage, which in turn will switch ON the circuit, and this cycle will keep repeating rapidly forcing the output to remain within the predetermined limits...
Mho said…
Ah...that is really clever. And how about under voltage? Typically when a power supply is loaded, the output tends to drop. How does this control method compensate for the voltage drop? Thanks.
Swag said…
Thanks! for overload situations you can configure a current resistor/transistor stage with the shut down pin to get the same results. The current sensing configuration can be studied in the following article

https://homemade-circuits.com/simple-current-sensor-circuit-modules/
Mho said…
thank you once again. Can this topology be used for building lead acid battery chargers?
Swag said…
yes it can be used, just make sure to adjust the output voltage as per the battery's full charge specs.
rahul talukdar said…
sir--smps modification for +-22 v dc 350 w----primary---turns --no of wires--gauge

secondary---turns --no of wires--gauge

also toroid coil specs

----thank you
Swag said…
sorry rahul, I am not sure about all these details, it will need to be calculated as per the following article:
https://www.homemade-circuits.com/how-to-design-a-flyback-converter-comprehensive-tutorial/
lieu said…
có ic nào thay thế đươc ir2153 không as mình muốn thử nghiệm mà tìm không ra
lieu said…
UC3842 có thay thế cho ir2153 không as
lieu said…
UC3842 có thay thế được cho ir2153 không as
Swag said…
Google cho "trình điều khiển IC nửa cầu với bộ dao động", bạn sẽ có thể tìm thấy nhiều sản phẩm thay thế

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