Simple Amplifier Design TDA2040 or TDA2050?

Thread Starter

Konur Bilak

Joined Jan 19, 2017
1
Hello everyone. I'm a ee student from turkey. I bought a pioneer ts-w310 4 ohms subwoofer and i want to build an amp for it. I'll build power amp on a pcb first, make it work, and than i'll build a seperate active low-pass filter on another PCB to add to it. I'll use a 60w 2x24v transformer to make a split supply stage, so thats my total power. I'm planning to use TDA2040 or TDA 2050 in a bridge design, please find circuit in attachment. So:

-I'll probably use lm7818's and lm7918's in parallel for supply regulation. Do you think making a regulator with bjt's and zeners worth the time to make it because of voltage boost?

-Which IC should i use for this? 2040 or 2050? I couldn't find info about low freq responses on neither datasheet. And didn't understand what it meant by "Power Bandwith = 100Hz" on 2040 datasheet. 2050 says BW is 20 Hz to 22 kHz which is good i assume. Can you please take a look at them and tell me which is more suitable and why? My priority is power. (TDA2050 has short circuit protection, which could be useful on trials)

-What size of a heatsink would i need? Datasheet says 13w max Pd for each IC so 26 w total. I'm thinking passive cooling.

Also i'm open for ic suggestions, if you know a more suitable ic for this job that doesn't need too complex external circuitry, please tell.

Thank you for your time and have a nice day :)

TDA2040: https://www.pollin.de/shop/downloads/D100014D.PDF
TDA2050: http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.CD00000131.pdf
 

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#12

Joined Nov 30, 2010
18,222
Let's do the math. Using 2 in a bridge configuration would deliver 9 amps into a 4 ohm speaker, but the best chip in this lot is limited to 5 amps. The 2050 can use the power supply you have, but it can't work as a bridged pair into 4 ohms.

Second: A 24 volt transformer will produce a voltage that is a little higher than 24 VAC RMS when it is unloaded, and the power lines have been running high around my house, like 125 volts instead of 115 volts.
So, you go (24V x 125/115 x 1.414 to get the peak capacitor voltage) x 1.1 for the uloaded voltage and you get 40.58 volts. Subtract 1 volt for the rectifiers and you can probably expect the 2040 chip to survive, but the 2050 has a safety margin. It can survive up to 50 volts.

The math says you can hit a 4 ohm speaker with 20 volts and use 5 amps. This kind of math shows the best use for what you have is a TDA2050 with a power supply just a little over 40 volts peak.

and you will need a heat sink rated at 3C/watt or less.
ps, now you know why your idea to use voltage regulators just went out the window. 24 volt transformers don't deliver 24 volts of DC.

pps, a class D switching chip will run a lot cooler, if there is one available. I think I've seen some completed Class D amplifier boards for sale on the Internet.
 
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