What is wrong with TPA3255?

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C

chermann

Member
Joined 2017
doctormord said:
I don't have that Power-Off-Pop feature on my implemenation of TPA32XX, neither 51 nor 55. The Pop comes from a race condition in fall-times of the power rails and can most likely avoided/tuned if the detection level for the voltage-supervisor is set tight to the supply voltage. If the level is to close to "nominal voltage", the amp will mute on high power with a weak supply. The EVMs solution with feed-forward capacitors is more prone to this effect as it kinda boosts dips in supply voltage change.


Using a TPS3802K33DCK, the threshold voltage for the SVS is 2.93V. The resistor divider 27k+3k3 then trips at about 27V.

Trip levels for other voltages:

34.9V: 36k + 3k3
32.2V: 33k + 3k3
30.3V: 30k9 + 3k3
29.6V: 30k + 3k3
27V: 27k + 3k3
24.2V: 24k + 3k3
22.5V: 22k + 3k3
20.7V: 20k + 3k3

So for a 36V system you may try 33k or 36k instead of 27k.
Click to expand...


Hi doc

i use 27k , a zener 4Z7 and 28Vpower for the start...... but its not working. VDD is 2,754Volt. then i checked the 3k3 for the divider....its not 3k3 --> 3562R
reset an TPS "ARK" is still 0Volt...ok....i have no 3k3 at home:rolleyes:
i try shortly to push 33V into it--> VDD is about 2.945V but the TPS"ARK" is still doing nothing=> Reset is 0V so the pin 18 of the TPA is 0V--> no sound
curious is that the MR of the TPS "ARK" is "open" but its about 2,74Volt??
did i miss something???:confused:


thx
chris
 
C

chermann

Member
Joined 2017
...thank you Doc...its working


changed R1 to 22kR 1% and at 29,25V the circuit is working:D
at the R2(3562) its 2,986V...so its in between the tolerance.


the out pop is still audible "loud" compared to the power on plop. in my lab i use a small 4 ohm speaker. will see/hear at my good speakers what happend when the amp is ready...


thx
chris
 
C

chermann

Member
Joined 2017
Fake Amp

Hi


i smal amp in a very tight housing is born:D ---Fake Amp !...its because the heatsink on both sides;)


after some installation ad de installation rounds:rolleyes:;) i found a good version for this housing...
opamps AD8599, muse input caps..decoupling caps 6x100µ/50 lowESR by Nichicon. voltage regulator is the original 2575 but with corrected coil and caps.

smps is the small LRS150-24 set to 28,5V ,
i tried a power indicator -small red LED at the bottom plate...but after the front panel its not really visible:p




chris
 

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A

Audio Mo

Member
Joined 2019
chermann said:
Hi


i smal amp in a very tight housing is born:D ---Fake Amp !...its because the heatsink on both sides;)


after some installation ad de installation rounds:rolleyes:;) i found a good version for this housing...
opamps AD8599, muse input caps..decoupling caps 6x100µ/50 lowESR by Nichicon. voltage regulator is the original 2575 but with corrected coil and caps.

smps is the small LRS150-24 set to 28,5V ,
i tried a power indicator -small red LED at the bottom plate...but after the front panel its not really visible:p




chris
Click to expand...

Any overheating issues? Do you think it could use a fan? or some sort of heat transfer to the case heatsinks?
 
C

chermann

Member
Joined 2017
Audio Mo said:
Any overheating issues? Do you think it could use a fan? or some sort of heat transfer to the case heatsinks?
Click to expand...

Hi audio Mo

if you read the complete posts you will find a constant power/current test with 40W ouput on both channels about 42minutes...then i got 102°C on the heatsink and yes the overheat protection of the TPA chip switched off

my personlly experiance with this board is for living room listening no fan is needed

chris
 
Last edited:
A

Audio Mo

Member
Joined 2019
chermann said:
Hi audio Mo

if you read the complete posts you will find a constant power/current test with 40W ouput on both channels about 42minutes...then i got 102°C on the heatsink and yes the overheat protection of the TPA chip switched off

my personlly experiance with this board is for living room listening no fan is needed

chris
Click to expand...

Thanks for the reply, I'm using the exact same case for my build, but I'm using this amplifier

SMPS600RS 48V 230V Power supply

The manual says it requires cooling fan, so I looked for an ultra quiet fan and found this (link below) which I'm planning to install in the back with slotted plate on the bottom rather than the top so air can circulate through PS heat sink. I can also install the fan on the top as well below the cover above the PS. The PS has the 12v aux output for that purpose.

Amazon.com: Noctua NF-A4x20 FLX, 3-Pin Premium Quiet Fan (40mm, Brown): Computers & Accessories

The fan is quiet on paper, but I'm worried about noise from interferance from the fan motor and amp board. What do you think?

Amp will be 3eaudio amp
 
C

chermann

Member
Joined 2017
Hi Audio Mo


well this is a "high" end smps so mine is the LRS150-24 (28) but i think this psu will not get in troubles if you will use it for living room sessions and more...:)


if you use really the same housing then it will be very interesting how you get all this into/on the cas;):D


chris
 
Z

zenit70

Member
Joined 2013
Hi everyone,
my friends had a marked improvement in the ratings of the tpa3116 battery-powered (24 V 12 A) rather than linear or worse switching.
Have you tried to power your TPA3255 on battery power?
I'm about to get a tpa3255, but 3audio has finished, would you advise me? I will also take a finite number which we recommend you make some changes yourself
 
Last edited:
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