Hi all,
As you know, TPA3251 has not been available from the main suppliers for a while and I think it will not be available for a long time.
So I would say decided to design a PCB for the TPA3250, which is the closest sibling of the 3251 (on paper at least).
Since the TPA3250 has a different pin configuration than the 3251, it was necessary to design a different PCB.
Provided that the basic design logic remains the same as TPA3250D2EVM, since the LM5010 is no longer available, I used XL1509 working at the same frequency as a step down regulator, an extra LC filter for its output and solid caps for bypass at the output. I also used a standard 78M12 as a linear regulator. And on the analog supply line has audio grade (like Silmic 2 or UKW) bypasses and parallel C0G 100nFs and X7R 1uFs.
I used a solid state power switch on the PCB and the MIC6315-31D4UY-TR, which provides an integrated 1.1 second reset delay. This will prevent pop during both power on and power off sequences.
For the main bypass capacitors, I added 2x Rubycon ZLQ 2200u/35v (16x25mm) and 100nF C0G and 1uF X7Rs in parallel.
At the output, there are UA8014-ALD 10uH double chokes, (produced by Colicraft especially for the TPA32XX series) 1uF MKP and 1000pF FKP capacitors in parallel.
All the power lines and the linear regulator are on the bottom side.
On the signal line no vias used.
....
So the result was a very minimalist PCB design, as you can see.
All lines were kept as short as possible, PWM circuitry and analog circuitry were kept as far away as possible to avoid RF interference.
If you have the opportunity to examine the design, I request you to express a positive or negative opinion, and to let me know if there is a design element that you would like me to change.
Of course, I expect suggestions from DIYers who want to make the project together
Best regards,
.
As you know, TPA3251 has not been available from the main suppliers for a while and I think it will not be available for a long time.
So I would say decided to design a PCB for the TPA3250, which is the closest sibling of the 3251 (on paper at least).
Since the TPA3250 has a different pin configuration than the 3251, it was necessary to design a different PCB.
Provided that the basic design logic remains the same as TPA3250D2EVM, since the LM5010 is no longer available, I used XL1509 working at the same frequency as a step down regulator, an extra LC filter for its output and solid caps for bypass at the output. I also used a standard 78M12 as a linear regulator. And on the analog supply line has audio grade (like Silmic 2 or UKW) bypasses and parallel C0G 100nFs and X7R 1uFs.
I used a solid state power switch on the PCB and the MIC6315-31D4UY-TR, which provides an integrated 1.1 second reset delay. This will prevent pop during both power on and power off sequences.
For the main bypass capacitors, I added 2x Rubycon ZLQ 2200u/35v (16x25mm) and 100nF C0G and 1uF X7Rs in parallel.
At the output, there are UA8014-ALD 10uH double chokes, (produced by Colicraft especially for the TPA32XX series) 1uF MKP and 1000pF FKP capacitors in parallel.
All the power lines and the linear regulator are on the bottom side.
On the signal line no vias used.
....
So the result was a very minimalist PCB design, as you can see.
All lines were kept as short as possible, PWM circuitry and analog circuitry were kept as far away as possible to avoid RF interference.
If you have the opportunity to examine the design, I request you to express a positive or negative opinion, and to let me know if there is a design element that you would like me to change.
Of course, I expect suggestions from DIYers who want to make the project together
Best regards,
Something doesn't looking right to me. I believe the op-amplifiers should work as SE-to-BAL converter. Secondly I can find some TPA3251 at Mouser
https://www.ti.com/product/TPA3251/part-details/TPA3251D2DDV
https://gr.mouser.com/c/?q=TPA3251
https://eu.mouser.com/c/?q=TPA3251
Thirdly I like BIG power decoupling capacitance (at least 4 capacitors) as far from the heat sink and output coils as possible + a thin metal sheet cover over smps grounded. Most important is the first watt (In low listening level I like to hear clearly "bendiir" dominating the rhythm 😉 )
Elias
https://www.ti.com/product/TPA3251/part-details/TPA3251D2DDV
https://gr.mouser.com/c/?q=TPA3251
https://eu.mouser.com/c/?q=TPA3251
Thirdly I like BIG power decoupling capacitance (at least 4 capacitors) as far from the heat sink and output coils as possible + a thin metal sheet cover over smps grounded. Most important is the first watt (In low listening level I like to hear clearly "bendiir" dominating the rhythm 😉 )
Elias
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Thanks for the answer Elias...
However I still cannot see any TPA3251 in stock;
Are you sure about that?
And regarding the opamps position;
They work as inverter; so the first is inverting SE input and the second is inverting the firsts output..
But as I know they must be as close as possible to the chip also.. What do you say about that?
Best regards,
However I still cannot see any TPA3251 in stock;
Are you sure about that?
And regarding the opamps position;
They work as inverter; so the first is inverting SE input and the second is inverting the firsts output..
So you say; should I move them to (may be the power input???) Ok then may be I can add a couple of them to the power input (top of the board)
But as I know they must be as close as possible to the chip also.. What do you say about that?
Best regards,
Standard circuits are using the first amplifier as non-inverting and the second as inverting (needs very stable op-amp as amplification factor is just 1)
Placement the chip at the bottom of the pcb maybe ?
Elias
Yes this is an alternative (I guess better alternative because of the CMRR) ,
But since I am referencing the Ti's TPA3250D2EVM reference design;
So I did the same.
May be an OPA1632 is also a good alternative for this position;
And about the main bypasses.. To positioning them to the solder side may be a good idea.. I will work on it. Thanks a lot.
Best regards Elias...
But since I am referencing the Ti's TPA3250D2EVM reference design;
So I did the same.
May be an OPA1632 is also a good alternative for this position;
And about the main bypasses.. To positioning them to the solder side may be a good idea.. I will work on it. Thanks a lot.
Best regards Elias...
In some cases (although OPA1632 has superior characteristics) I like better OPA6134 and that's because the 4 op-amps are on the same chip, so hopefully better balance between the 2 channels. But that is my personal preference although - due to very limited space SOP-14 - add headaches to designers
(lower Cross-talk)Regards
Elias
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AIYIMA uses the TPA3250 in their T9 hybrid tube/Class D amp. Probably reference TI design I would imagine.
Very compact "all in one" amplifier.. I guess tubes used as buffer. By the way are you sure about they use TPA3250 in this amplifier?
You mean; OPA4134?? I like 134 series sound too much too..In some cases (although OPA1632 has superior characteristics) I like better OPA6134 and that's because the 4 op-amps are on the same chip, so hopefully better balance between the 2 channels. But that is my personal preference although - due to very limited space SOP-14 - add headaches to designers
Regards
Elias
Cool!
Make it without a "switcher"? I know it can be done silent but it is a risk... it switches....
And then, if it is not "only" minimalistic, but also aim for the highest SQ, maybe a step up in the DC regulators... LT?
//
Make it without a "switcher"? I know it can be done silent but it is a risk... it switches....
And then, if it is not "only" minimalistic, but also aim for the highest SQ, maybe a step up in the DC regulators... LT?
//
I use the switch as power-on/off pop supressor. Beause according to my experiences TPA32xx series are "loudy" in power sequences...
If you look closer to the power switch; NO side is connected to the MOSFET and the NC side is connected to the RESET pin of TPA.. So at least on paper I should hear no switch on/off pop... 🤔
Ok... we can add a simple upc1237 like power on delay circuit on the ouput instead of this. But why? This way is more simple..
By the way, PCB's are received..
I am waiting for the components from digikey.. Soon I will report the results.. 🙂
I am waiting for the components from digikey.. Soon I will report the results.. 🙂
The name of the company ? Minimum order quantity (I believe they accept payment in Euro)
Eias