TDA8920B - Design Partners Wanted

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Rodo

Rodo

Member
Joined 2007
Hi. I´m testing last version of TDA8920: TDA8920B. PCB is not in datasheet so I´m starting from begining. I´m making a versatile PCB but I need some assistance with schematics and lay-out issues. I plan to use 2 TDA8920B in BTL mode but also with 4 x SE ouputs. Imputs will be selected whith jumpers. Also all design will be modular.
I have experience with PCBs development.
If somebody wants to work with me in project is wellcome. I use Protel but I can share any format output (.pcbs, gerber files, png, corel, etc.). Post is opened.
 
Rodo

Rodo

Member
Joined 2007
Ipanema said:
There's lots of crosstalk between the channel when I tested the evalution board. Maybe you should consider only use it in BTL mode.
Click to expand...

Hi Ipanema.
Datasheet specification for channel separation is about 70 dB. Only reference I found in both datasheets (8920 and 8920B) about advantage of using BTL is because pumping effect in supply.
Did you tested 8920B with evaluation board PCB in datasheet for 8920 or you made a new lay-out?
Schematic for 8920B has some changes in components and supply. Could it be reason for crosstalk?
I have not tested any of both so I have not idea.
Reason to use SE as BTL is because I have some Hifi speakers with low RMS power limit (about 35 W 8Ohms). Also I plan to use BTL for SB and any other configuration I could test with more powerful speakers.
 
Rodo

Rodo

Member
Joined 2007
fumac said:
hi Rodo

i had make 8920B

use 2 TDA8920BTH in BTL mode but also with 4 x SE ouputs

IS JUST LIKE ME

RG
FUMAC
Click to expand...


Hi fumac.
I followed some posts you made for PCBs for hi frequencies considerations and I learned a lot! Also I surfed your site and amplifiers you made are amazing! You could make a lot of money with UPS and swithching power supply boards because hi frecuencies for that devices are very dificult to use.
Returning to amplifiers: I will try some easier one.
I found 8920B very interesting for beginers.
Did you have any problem with crosstal in SE configuration?
 
F

fumac

Member
Joined 2006
class-d.net
rodo

when i was a beginer(even this day ,i am newb )
i tryto design class-d for my project a wireless speaker
i'm start at 8920
but it's not very easy to dowith it

inside the chip, low signal and high power mixer
so must to attention to the decoupling

i design 3 versions pcb, then make 8920 ok
after that, i found the chip of class-d is not good at high power
so changto other way

good luck

rg
fumac
 
Rodo

Rodo

Member
Joined 2007
fumac said:
rodo

inside the chip, low signal and high power mixer
so must to attention to the decoupling

i design 3 versions pcb, then make 8920 ok
after that, i found the chip of class-d is not good at high power
so changto other way

good luck

rg
fumac
Click to expand...

Hi again fumac.
Do you think a chipset solution is better way? It means using a chip to PMM and other for power output?
I don´t need hi output power. 80+80 W is enogh for me but I don´t want to use a huge heatsink.
I couldn´t find other chips to use with easy board lay-out.
Idea is to use double side boards but without metalized holes using top layer for ground plane.

Trypath has some different options than 8920 but I can´t get chips in Argentina.
 
F

fumac

Member
Joined 2006
class-d.net
Rodo said:


Hi again fumac.
Do you think a chipset solution is better way? It means using a chip to PMM and other for power output?
I don´t need hi output power. 80+80 W is enogh for me but I don´t want to use a huge heatsink.
I couldn´t find other chips to use with easy board lay-out.
Idea is to use double side boards but without metalized holes using top layer for ground plane.

Trypath has some different options than 8920 but I can´t get chips in Argentina.
Click to expand...

i have tested 8920 and class-t(100w@4r) in same speakers(tannoy), personal chiose 8920, the bass of 8920 is better than the class-t, the treb of class-t is better than the 8920.
no one is better than other one in all test. so i delete all of them in my new projects.

about chip set

i did not find any chipset is good Enough at class-d ,(i just read the pdf of them,no interest to test them again),

rg
fumac
 
Rodo

Rodo

Member
Joined 2007
Ipanema said:
I still prefer GC over class D thus far. Enjoy building......
Click to expand...


Thanks for your answer. I have a lot experience with STK based amplifiers. I avoid using STK because the size of heatsink. Also they generate a lot of heat with a huge heatsink. I have not use GCs.
As you tested GCs, do they have same problems with heat?
Thanks a lot, Rodolfo:)
 
Ipanema

Ipanema

Member
Joined 2004
GC does not generate much heat as with most Class AB amplifier. However the heat does increase proportional with the supply voltage. If you face heat problem with your heatsink, then just lower the supply voltage will do. :) The lowest supply I use for LM3875 is +/- 16V and they are stone cold with just a puny heatsink.
 
Rodo

Rodo

Member
Joined 2007
Hi. I´m finishing first PCB for TDA8920B (SMD Version). I will make it public soon.
As I plan to use 2 chips in same amplifier I will make one PCB for each chip and use connectors to joint modules. Third module will be inputs, mute control, osc. and supply circuit.
I want to reduce redundant parts of circuit. Is it possible to joint both chips starting with a common VDDP, VDDA, VSSA and VSSP? It means using just one supply circuit?
Thanks for your help, Rodolfo
 
Rodo

Rodo

Member
Joined 2007
Ipanema said:
GC does not generate much heat as with most Class AB amplifier. However the heat does increase proportional with the supply voltage. If you face heat problem with your heatsink, then just lower the supply voltage will do. :) The lowest supply I use for LM3875 is +/- 16V and they are stone cold with just a puny heatsink.
Click to expand...

Thanks for your answer. If I can´t build this class D amplifier I will start with GC.

;)
 
F

fumac

Member
Joined 2006
class-d.net
Rodo said:
Hi. I´m finishing first PCB for TDA8920B (SMD Version). I will make it public soon.
As I plan to use 2 chips in same amplifier I will make one PCB for each chip and use connectors to joint modules. Third module will be inputs, mute control, osc. and supply circuit.
I want to reduce redundant parts of circuit. Is it possible to joint both chips starting with a common VDDP, VDDA, VSSA and VSSP? It means using just one supply circuit?
Thanks for your help, Rodolfo
Click to expand...

phps before u send it to make it, u can post it here, many people can tell u some thing;)

rg
fumac
 
Rodo

Rodo

Member
Joined 2007
1st. Draft PCB - Some questions

Hi.
I finished first board.
You could find images at:
http://www.bairesshopping.com.ar/pcb/pcb.html
or here at the bottom.

There are 2 boards:
- TDA´s one: It contains TDA8920B, complete output stage as describes datasheet, some components from input circuit and some components from filter power supply input. Plan is to use 2 boards per amplifier. I think It´s finished.
It´s double side through hole but TDA. To avoid using metalized holes, I used some capacitors that let connect both layers soledering pads of both sides. Top side is most for GND ground plane.

- Main board: It contains common parts to use 2 x TDA8920B boards. I made it just single side PCB. Some components from Power Suppy, Mode Control, External Oscillator and audio inputs are in this board to reduce redundant circuit. Main board is not finished yet: just 1 TDA´s board is connected and to use with internal oscillator. Also some space at right is keept to include audio preamplifier or just to fit Power Suppy rectifier and capacitors.


I have some questions about this project:
- Is it ok the way a separate supply stage in both boards?
- Same question for audio inputs.
- Is it ok lay-out?
- Plase check GND and FGND as I separe tracks to balance load. Is it the idea?

Thanks, Rodolfo

An externally hosted image should be here but it was not working when we last tested it.
 
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