TPA3255 / TPA3251 / TPA3245 Rev.1B Final
Table of Contents
In continuation / expansion of implementations based on the TPA3255 / TPA3251 / TPA3245 now the final approach of amplifier design for the Akita family. Differently to the past designs , the analog front end is now implemented on a dedicated circuit board powered by a balanced supply. This results in the ability to provide different approaches of signal input/suppl<. For example, it now is possible to directly feed the amplifier with I2S by i.e. a PCM5242 .
This post is in continuation to the following articles:
http://www.360customs.de/2015/07/tpa3251d2-2-x-175w-stereo-350w-mono/
http://www.360customs.de/2016/10/tpa3255-tpa3251-tpa3245-universal-one-for-all/
AGML battery charger
Visualization Rev1.B
TPA3255 Rev1.A vs Rev1.B with AFE
TPA3255 Rev1.B with AFE
Build
A first trial assembly before the boards were fitted.
TPA3255 Rev1.B Testbuild
2 boards with an AFE module each were built up. One was locally measured and valued, the other went to "Voltwide", member of the forum "stromrichter.org".
TPA3255 Rev1.B Testsystem #1
TPA3255 Rev1.B Testsystem #2
TPA3255 Rev1.B Heatsink
The supply of the AFE module (analog front end) and AVCC of TPA32XX is done by a LM5017 in flybuck configuration for +/-12V. The converter runs at approx. 850kHz, far outside of the audio spectrum.
TPA3255 Rev1.B Flybuck
Measured values / performance
Supply analog +/-AVCC
For the LM5017 in flybuck configuration there are these +/-AVCC ripple plots:
LM5017 AVCC+ output
LM5017 AVCC- output
The RMS ripple is less than 10mV, without any ripple no COT would work. Related to +/-12V, the ripple is less than 0.1%. With additional 100n, the ripple at the AFE pinheader shows up as follows:
LM5017 AVCC- 100n Pinheader AFE
LM5017 AVCC- 100n Pinheader AFE
There's an additional RC filtering followed by a fedd-trough capacitor on the AFE module.
AVCC+ AFE filtered
2mV ripple equals ro 0.017%, relative to AVCC = 12V. In the AFE related OPA1654 offer 30dB PSRR at 850kHz, with better than 65dB in the 20 kHz audio band.
Audio THD/THD+N
The design delivers the following performance on 3.8Ohm load resistance:
1W
THD: 0.0016%
THD+N: 0.02%
K1: 11.9dBV
K2: -94.22dBV
K3: -89.8dBV
K1/K2: 106.12dBV
K1/K3: 101.7dBV
10W
THD: 0.0016%
THD+N: 0.013%
K1: 16dBV
K2: -90.4dBV
K3: -82.5dBV
K1/K2: 106.4dBV
K1/K3: 98.5dBV
100W
THD: 0.0039%
THD+N: 0.046%
K1: 25.9dBV
K2: -68.4dBV
K3: -65.4dBV
K1/K2: 94.3dBV
K1/K3: 91.3dBV
Plots for 3.8Ohm load in BTL at PVCC = 51V, 600kHz AFE module with minimal PFFB at 1 kHz and for different frequencies:
THD vs POUT into 3R8 at 51V 600kHz BTL
THD f(freq) vs POUT into 3R8 at 51V 600kHz BTL
Utilizing prefilter PBTL, connecting the TPA32XX outputs together right before the output filter, result in even lower values. The test setup:
TPA3255 Rev1.V PBTL Testsetup
Measurements taken with a load of 5.0Ohm connected at PVCC = 30V without PFFB and AFE module:
THD vs POUT into 5R0 at 30V 600kHz PBTLTHD vs POUT into 5R0 at 30V 600kHz PBTL no AFE PFFB
The following can be achieved with a load of 10.0Ohm:
THD vs POUT into 10R0 at 30V 600kHz PBTL no AFE PFFB
Supply
In the same form factor (10x10cm), an LLC power supply module was developed by "Voltwide" which provides 50V for the powerstage and 12V AUX. A unit in 10x10x10cm results with the appropriate bolts.
TPA3255 Rev1.B 50V Voltwide LLC #1
TPA3255 Rev1.B 50V Voltwide LLC #2
Excellent job. I am looking to build an amplifier. How can I get a pre-assembled plate, or just the plate?
I only have some spare PCBs available. (Unpopulated)
Hello! Is it possible to buy a circuit from you?
Hello. Very good project !!!! Interested in. Can I get a fee from you? Please give an answer!
At the moment, I did not have a single printed circuit board for sale.
Hello! I studied your project on TPA3251 for several days. I liked it very much! I would very much like to purchase a board and assembly instructions from you. Please give me the price for TPA3255 Rev1.B and 50V Voltwide. I will collect on TPA3251. Thanks in advance.
Nice job!
Which software did you use for the THD measurements?
The art.
Hello,
would it be possible to receive or purchase a scheme for the whole project? I was very interested in the reviewed results and I would also like to build this amplifier. Or is it possible to buy an entire amplifier already ready?
Regards
Peter
Hi i wood like to have more information about ordering , prices… Thank you and best regards.
Hi, can You sell the pcb ? thanks !
Is it possible to acquire and this amp for sale?
There are boards for selbstbestücken available ready built amplifiers are not available.
Very nice job!