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Old 25th September 2010, 09:01 PM   #1
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Default Offline full-bridge SMPS

I'm developing a 5.2-amp and need a powerfull smps.
Channels:
5x TDA7293 (50W into 8Ohm)
2x Class D 500W into 4 Ohm

I need +-35V for the TDA7293 and at least +-65V for the class D-amps.

I bought the smps-bible "Switchmode power supply handbook" by Keith Billings, which tells me to use a fullbridge-topology for high power smps.

Now i have a few questions:
Whats the best solution for controlling a smp for an amp? Any IC-recomendations?

Is it a problem for generating 2 different voltages out of one smp?

Most bridge-converters use impulse-transformers instead of fet-drivers and optocouplers - why?
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Old 25th September 2010, 09:40 PM   #2
luka is offline luka  Slovenia
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I would use 2 supplys, one for 5 tda's (if 8R load), and one for classD's... both can be half bridge

for controller, if started from 0, use something like mc34025, which is modern smps controller. You could make 2 or even more voltages from one, but I feel its better to have 2, that are deperad for surround and bass. And it's more easy to make 2 that are not that powerfull, also depends a lot on you, have you done anything like this before?

Most that converters? PC's? I have never used transformers, but did fet drivers
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Old 25th September 2010, 10:41 PM   #3
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Quote:
Originally Posted by luka View Post
And it's more easy to make 2 that are not that powerfull, also depends a lot on you, have you done anything like this before?
Not in such high powerlevels, but i have my book which also includes snubbers and since it's my diploma project, i'm supported by a few professors. One of them is experienced in smps, another one specialises in EMI.

Quote:
Originally Posted by luka View Post
Most that converters? PC's? I have never used transformers, but did fet drivers
I don't remember seeing a schematic with fet-drivers, also the datasheets i've seen before are using transformers.
But i think fet-drivers works better. Maybe transformers are cheaper and that's why they are used in mass production?

But are integrated controller supporting both transformers and drivers/optocouplers?
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Old 25th September 2010, 11:13 PM   #4
luka is offline luka  Slovenia
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Quote:
Originally Posted by der Papst View Post
I don't remember seeing a schematic with fet-drivers, also the datasheets i've seen before are using transformers.
But i think fet-drivers works better. Maybe transformers are cheaper and that's why they are used in mass production?

But are integrated controller supporting both transformers and drivers/optocouplers?
If you ask me, they are more bullerproof, high voltage insulation, they can have nice start up done with them... but you do need to calculate them, but after that its just copy and paste all over...

I don't know, you tell what direction you want to take, I'm sure it can be diffrent for individual

You need to set parameters, under which supply will have to work, input voltage range, output voltage, power, ripple... type of controller(voltage or current), type of feedback
I mean that all easy of will be fun to debug and make it works great
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Old 25th September 2010, 11:14 PM   #5
luka is offline luka  Slovenia
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Quote:
Originally Posted by der Papst View Post
But are integrated controller supporting both transformers and drivers/optocouplers?
Yes, most have ~1A output, that can drive fets or drivers or even gate trafos
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Old 26th September 2010, 07:50 PM   #6
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Thanks luka

I'll talk to my prof. and develope a concept with him. I'll post the progress and further questions here
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Old 27th September 2010, 06:59 AM   #7
luka is offline luka  Slovenia
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cool, can't wait to see progress. When is the end time for this project?
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Old 2nd October 2010, 09:34 AM   #8
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I've found here a class D-ic, also including the bridge and feedback:TI tas5630.
In the datasheet, a supply reference design is mentioned, designed for the ic: http://focus.ti.com/lit/ug/slou293/slou293.pdf

It doesn't make sense to design a SMPS when TI delivers a proven one.

Now, a SMPS for my 5xTDA7293 remains and a SMPS for 500W is simpler to design than one for 1,6KW.

Has somebody built Ti's reference smps?
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Old 7th October 2010, 08:37 PM   #9
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Quote:
Originally Posted by luka View Post
I would use 2 supplys, one for 5 tda's (if 8R load), and one for classD's... both can be half bridge
What's the advantage of a halfbridge-smps?
I know many advantages of fullbridge-smps and the only disadvantage is the need of a high-side fet-driver which costs <1...

Does anybody know a good full bridge-controller?

BTW: Why are some people here preferring impulse-transmitters to fet-drivers?
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Old 7th October 2010, 08:54 PM   #10
Krisfr is offline Krisfr  United States
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I like this page for info...

SMPS Switching Power Supply Topologies: Comparison and Selection

and

http://www.onsemi.com/pub_link/Collateral/SMPSRM-D.PDF

Last edited by Krisfr; 7th October 2010 at 08:56 PM.
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