|
Home | Forums | Rules | Articles | diyAudio Store | Blogs | Gallery | Wiki | Register | Donations | FAQ | Calendar | Mark Forums Read |
Class D Switching Power Amplifiers and Power D/A conversion |
|
Please consider donating to help us continue to serve you.
Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving |
![]() |
|
Thread Tools |
![]() |
#1 |
diyAudio Member
|
![]()
TI has released TPA3251d2 'AKITA" higher power analog in class D chip with higher order modulator similar to Hypex NCore but with pre filter feedback. First heard about it at CES 3+ years ago. Can be configured as 1,2,3 or 4 channel with 36 volt supply for output stage.
|
![]() |
![]() |
#2 |
diyAudio Member
|
I'm really curious how this chip sounds. Pretty impressive description:
"TPA3251D2 is a high performance class-D power amplifier that enables true premium sound quality with class-D efficiency. It features an advanced integrated feedback design and proprietary high-speed gate driver error correction (PurePath™ Ultra-HD). This technology allows ultra low distortion across the audio band and superior audio quality." I hope the chinese manufacturers will take the first steps soon.
__________________
"We can hear everything we measure, but we can't measure everything we hear. Let your ears be your guide." |
![]() |
![]() |
#3 |
diyAudio Member
Join Date: Jan 2008
|
![]()
This is a closed loop part with pre-filter feedback. THD vs power (at 1KHz) & THD vs Frequency curves from June 2015 datasheet attached. I'd like to try a differential input, BTL output implementation.
TI website has samples: TPA3251D2 | Mid/High-Power Class D Amplifiers | Audio | Sample & buy |
![]() |
![]() |
#4 |
diyAudio Member
Join Date: Oct 2007
|
Yeah, let's make a small board <=10x5cm.
![]()
__________________
|
![]() |
![]() |
#5 |
diyAudio Member
Join Date: Oct 2007
|
Some short calculation for the required heatsink, worst case:
Rds_on (high/low side): 0.1R Imax: 14A Tambient: 30°C Rth_jc(Top): 0.36°C/W Power dissipation per channel: Pd_channel = I²R = Imax²*2*Rds_on = 14A²*2*0.1R = 196A*0.2R = 39.2W Power dissipation total: Pd_total = 2*Pd_channel = 2*39.2W = 78.4W Tcase = Tjunction - Rth_jc * Pd_Total = 125°C - 0.36°C/W * 78.4W = 125°C - 28.224°C = 96.776°C Rth_heatsink = (Tcase - Tambient) / Pd_total = (96.776°C - 30°C) / 78.4W = 0.85°C/W Rth_heatsink includes thermal conductivity of heatsink grease. -------------- Lets do the calculation again for Irms (sinus power): Rds_on (high/low side): 0.1R Imax: 14A Tambient: 30°C Rth_jc(Top): 0.36°C/W Power dissipation per channel: Irms = Imax*sqrt(2) = 14A*0.707 = 9.9A Pd_channel = Irms²R = Irms²*2*Rds_on = 9.9A²*2*0.1R = 98A*0.2R = 19.6W Power dissipation total: Pd_total = 2*Pd_channel = 2*19.6W = 39.2W Tcase = Tjunction - Rth_jc * Pd_Total = 125°C - 0.36°C/W * 39.2W = 125°C - 14.112°C = 110.888°C Rth_heatsink = (Tcase - Tambient) / Pd_total = (110.888°C - 30°C) / 39.2W = 2.1°C/W Rth_heatsink includes thermal conductivity of heatsink grease. Much better. ![]() As music is normally not pure fixed frequency sine wave the maximum temperature will likely not reached even at full power. ---------------------------------------------------------------------- Lastly, for normal use, with an estimated programm factor of 0.5 there will be: Rds_on (high/low side): 0.1R Imax: 14A Music programm factor (mpf): 0.5 Allowed max junction temperatur: 90% from Tj = 0.9*125°C = 113°C Tambient: 35°C Rth_jc(Top): 0.36°C/W Power dissipation per channel: Irms = Imax*sqrt(2) = 14A*0.707 = 9.9A Iprog = Irms * mpf = 4.45A Pd_channel = Iprog²R = Iprog²*2*Rds_on = 4.45A²*2*0.1R = 19.8A*0.2R = 3.96W Power dissipation total: Pd_total = 2*Pd_channel = 2*3.96W = 7.92W Tcase = Tjunction - Rth_jc * Pd_Total = 113°C - 0.36°C/W * 7.92W = 113°C - 2.85°C = 110.15°C Rth_heatsink = (Tcase - Tambient) / Pd_total = (110.15°C - 35°C) / 7.92W = 9.5°C/W
__________________
|
![]() |
![]() |
#6 |
diyAudio Member
Join Date: Oct 2013
|
|
![]() |
![]() |
#7 |
diyAudio Member
Join Date: Oct 2007
|
Sorry, but i can't find them on the TI page. (With analog inputs)
__________________
Last edited by doctormord; 16th July 2015 at 04:11 PM. |
![]() |
![]() |
#8 |
diyAudio Member
Join Date: Oct 2013
|
this is one ds:
http://www.ti.com/lit/ds/symlink/tas5756m.pdf this is the user manual for the software: http://www.ti.com/lit/ug/slau577a/slau577a.pdf |
![]() |
![]() |
#9 |
diyAudio Member
Join Date: Oct 2007
|
Thats something totally different. Digital Inputs, less output power, less operating voltage..
__________________
|
![]() |
![]() |
#10 |
diyAudio Member
Join Date: Oct 2013
|
yes
|
![]() |
![]() |
Thread Tools | |
|
|
New To Site? | Need Help? |