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Old 28th January 2011, 04:46 PM   #1
riktw is offline riktw  Netherlands
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Default TDA8954 output filter

Hello

i am busy with a TDA8954 PCB.
the TDA8954 looks like a fairly easy IC for a high power amplifier.
PCB design should work out, PCB will be professionally made in china (so cheap )
but one thing bothers me, the output filter, especially the inductors.
i can imagine these should be able to withstand some serious currents.
i want to make a stereo amplifier for 4 ohm speakers, so roughly 200 watts per channel.
but a classmate wants to make a BTL version of it (8 ohm 400 watts)
what coils are good for this kind of currents?

when looking trough the coilcraft site i found two types look promising:
Coilcraft PCV-1 Vertical Mount Power Chokes
Coilcraft VER2923 High Current Power Inductors

would one of those types be good enough to handle high currents and have decent audio performance?

datasheet TDA8954:
http://www.nxp.com/documents/data_sheet/TDA8954.pdf

Rik
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Old 28th January 2011, 08:20 PM   #2
beun is offline beun  United States
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The VER2923 looks like a good candidate with a nice flat inductance versus current curve, seems shielded too. I didn't see a place where you can buy them though.
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Old 28th January 2011, 08:34 PM   #3
riktw is offline riktw  Netherlands
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i kind of sampled 4 to try them hehe
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Old 29th January 2011, 12:42 AM   #4
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The main problem I have found with class d output inductors is some of them cook far too easily.

I bought a selection and used the best one from then on.
One of the poor ones ran at 180 degrees C !
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Old 30th March 2015, 10:28 PM   #5
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Dear Nigel,

using your previous experience, please could you help me to select the best inductor regarding effectiviness, in order to decrease the temperature on it? I'm suffering a lot to find the right inductor matching with the TDA8954.

Thanks in advance.
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Old 23rd April 2016, 05:07 AM   #6
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hello
i need proteus pcb for tda 8954th(smd).
please help me...
thanks.
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Old 23rd April 2016, 09:53 PM   #7
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Quote:
Originally Posted by jarproyectos View Post
Dear Nigel,

using your previous experience, please could you help me to select the best inductor regarding effectiviness, in order to decrease the temperature on it? I'm suffering a lot to find the right inductor matching with the TDA8954.

Thanks in advance.
t106-2 works very well with my irs2092 based amps.
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Old 24th April 2016, 01:59 PM   #8
Pafi is offline Pafi  Hungary
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t106-2 is fine, but it's only a core. Regarding to inductors the key is low AC idle loss. Sadly this is almost never specified (correctly). This requirement is generally contradictional to low DC resistance, so any inductor specified for very low DC resistance is likely to heat very much in a ClassD amp. DCR of 15 to 100 mohm is fine for 4 ohm load. But obviously this value doesn't guarantee anything, only a sign.

Generally a low AC loss comes together with high saturation current (air gap), but this also has to be checked.
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Old 24th April 2016, 02:34 PM   #9
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Quote:
Originally Posted by Pafi View Post
t106-2 is fine, but it's only a core. Regarding to inductors the key is low AC idle loss. Sadly this is almost never specified (correctly). This requirement is generally contradictional to low DC resistance, so any inductor specified for very low DC resistance is likely to heat very much in a ClassD amp. DCR of 15 to 100 mohm is fine for 4 ohm load. But obviously this value doesn't guarantee anything, only a sign.

Generally a low AC loss comes together with high saturation current (air gap), but this also has to be checked.
The core material makes a huge difference.
Iron cores at hf will get very hot.

My class d amp output filter inductors run very cool.
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Old 25th April 2016, 07:36 PM   #10
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Quote:
Originally Posted by riktw View Post
Hello

i am busy with a TDA8954 PCB.
the TDA8954 looks like a fairly easy IC for a high power amplifier.
PCB design should work out, PCB will be professionally made in china (so cheap )
but one thing bothers me, the output filter, especially the inductors.
i can imagine these should be able to withstand some serious currents.
i want to make a stereo amplifier for 4 ohm speakers, so roughly 200 watts per channel.
but a classmate wants to make a BTL version of it (8 ohm 400 watts)
what coils are good for this kind of currents?

when looking trough the coilcraft site i found two types look promising:
Coilcraft PCV-1 Vertical Mount Power Chokes
Coilcraft VER2923 High Current Power Inductors

would one of those types be good enough to handle high currents and have decent audio performance?

datasheet TDA8954:
http://www.nxp.com/documents/data_sheet/TDA8954.pdf

Rik
first excuse me because of my english , its bad.
about current of filter :
if power supply is +-40 volts, for 200w+200w ,output current of Ic is 2.5 A+2.5A
for both BTL mode (400w )current is 5A because tow filters are series with 8 ohm speaker .
so the filter at least should be 2.5 A for normal and 5A in BTL mode.
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