100W Audio Amplifier TDA7294.

TDA7294 is an integrated, monolithic, Class AB audio amplifier designed specifically for Hi-Fi applications. The IC has a DMOS output stage and can deliver 100W RMS into an 8Ohm speaker at +/-38V dual supply. The TDA7294 has low noise, low distortion, good ripple rejection and can be operated from a wide range of supply voltages. The IC has built in short circuit protection and thermal shutdown circuitries. The IC is available in multiwatt 15V and multiwatt 15H packages.

Description.

In the circuit TDA7294 is configured to provide 100W output power into an 8Ohm loudspeaker at +/- 38V supply. C8 is the input coupling capacitor and the input is applied to the non-inverting input (Pin3) of the IC. C3 and C9 are power supply filter capacitors while C10 and C4 are bypass capacitors. C2 is the bootstrap capacitor. RC network comprising of R1 and C1 improves the high frequency stability of the amplifier and also prevents oscillations. R2 and C6 sets the mute time constant while R3 and C5 sets the standby time constant. S1 and the mute switch and S2 are the standby switch. R5 is the input resistance and the amplifiers input impedance has a direct relationship to its value. R4 and R6 is used for setting type closed loop gain and with the used value, gain is 30dB. C2 is a feedback capacitor and it also provides DC decoupling.

Circuit Diagram.

100W amplifier TDA7294
TDA7294 100W amplifier

Notes.

  • The supply voltage range is +/- 10V to =/-40V DC.
  • Heat sink is required and its thermal resistance should be around 0.038 degree Celsius/Watt.
  • Use an 8 Ohm 150W speaker as the load.
  • For 100W output the supply voltage must be +/-38VDC.
  • The power supply must be well filtered and free of ripples.
  • If ripples are present in the power supply it may cause oscillations.
  • VM = 1.5V is the mute ON threshold and VM=3.5V is the mute OFF threshold.
  • VSTBY = 1.5V is the standby on threshold and VSTBY = 3.5V is the standby OFF threshold.
  • Typical input resistance of TDA7294 is 100KiloOhm.
  • Frequency response is 20Hz to 20KHz.
  • 145 degree Celsius is the threshold for thermal shutdown. Slew rate of TDA7294 is 10V/microsecond and the open loop voltage gain is 80 dB.
  • Quiescent current of TDA7294 is approximately 30mA and its maximum value is 65mA.
Author

84 Comments

  1. tda7294 5.1 board speaker output is humming pls help me

  2. Hello sir,
    i am a Student.
    -Do you have +/- 38v power supply circuit diagram for the amplifier circuit.
    -is there any way i can use the same circuit to power a 4 ohm speaker.

  3. Hlo i need tda7294 ic maximum input volt and amp. Plz help me

  4. hi sir
    Can i use ±45v 5 ampere ???
    pls Ripley me sir.

  5. midhunlal

    Which is the +line of speaker in 7294 bridge amp i will send the circuit image plz answer

  6. Matej112

    Hey,

    this circuit work 100% ?, because im trying to make one of these.

    Please answer.

  7. C George Jacob

    I am confused as to which amplifier circuit I should assemble. TDA2030A in conjunction with BD249, BD250 output transistors, 120W output into 4 ohms load OR the TDA7294 based circuit.
    Kindly let me know about the i/p required, s/n ratio, distortion, low and high frequency response etc. Comparison.

  8. Premkumar

    Dear Seetharaman Sir,
    I wanted to make a professional quality Audio Mixer with 8 to 12 channels. I have seen such a circuit in Elector magazine very long back. Sir Could you please help me to get the diagram and PCB layout and other details for the making of it?. I used to read your Computer programming lessons came in the EFY. That was very useful at that DOS , WS, dbase and Lotus time

    Thanks in advance
    Premkumar

  9. Endurance

    What are the components for this circuits pls list them out

    • can i use +/-32v 1.6 amp transformer to power this amplifier

  10. what are the component of this circuit pls list it out

  11. hi, anybody have pcb layout for this…and where do I get power for VM and VSTBY…or can I just leave it without connecting them….thanks

  12. This design is inefficient. A much more efficient design is published in the datasheet for this component on page 10.

  13. i read the notes for this circuits. but i cant understand what is VM and VSTBY . how can i connect them to the circuit please help me

    • You need to look at the datasheet, it shows how to connect them.

  14. Aiza Basquina

    Try this 300W Hi-Fi mosfet amplifier http://adf.ly/vNFeo the is superb.

  15. Midhun mp

    Sir can i use it as a bridge mode ?THEN How much power will get 8ohm load? Please clarifi my doubt sir,

    • seetharaman

      It can be used in bridged mode. It will around 150watts RMS into 8 ohms load. 4ohms load not recommended.

  16. pramith.k

    sir I have 2 100w speakers ,so I need simple and effective audio amplifier for this ….plz hlp me

  17. Hello sir, i need circuit diagram to get 38vdc out of 2x24vac Supply if you can help me please?

  18. Hello sir ,please I need a diagram that will help me amplify my factory set car audio from 50watts too 150 / 250 watts from a 12vdc supply with parts list please I will be highly appreciated

    • Seetharaman

      Hi Yesh It is not directly possible without driver and output transformers with 12 volt DC supply (like output stage in a PA Amplifier). With only a driver transformer and two darlinton power transistors or Mosfet transistors and a switched mode power supply of 12 VDC to plus minus 45 volts DC @ 5amps you can achieve 200 to 250 watts.

  19. abubakar

    pls sir can u post a tda7560 (50×4 watt) circuit diagram?

  20. Midhunmp

    Sir, I am a +2student. I have 25 0 25 volt 5amp ac transformer . If i connect these to the circut what power will get on 4ohm load? Please help me sir….. I hope ur replay

    • Seetharaman

      You will get 70 watts RMS into 4 ohms load at 0.5% and 85 Watts RMS into 4 ohms load at 10% distortion.

  21. Midhunmp

    Sir
    I have 25v 5amp Ac transformer and 10inch 4ohm subwofr with bass filter. If i connect these to the circut what power will get. Please help me…

  22. Hi folks, I’ve spent some time -nights- with 7294, asking it for 100 watts. It totally refused to do so.
    +/- 24 V at the rails you get 25 W over 4 Ohms – and that’s it. Higher voltage, more load (<4 Ohms) – you always get 25 Watts. This IC blushes in stage fright.
    But I was successful: ST itself offers a much more sophisticated circuitry in their datasheet and i managed to build it and to make it yell 110 Watts over 4 Ohms.
    But do I really need this kind of minstrel show:
    +/-25 V AND! +/-50 Volts, added eight transistors and so on? Everything well painted on a double layer pcb postcard?
    I don't need that staying with my old 2n6609 and 2n3773.
    Have Fun!
    Goetz from Germany

  23. Chiliman

    If the ic would have been broken , would anything in the circuit burn up with power connected?

    • Seetharaman

      Yes the ic is cracked means some portion of electronic chip is damaged.

  24. Chiliman

    Should gnd be connected to the chassi and the gnd in the ac socket?

    • Seetharaman

      Gnd indicates a common 0 volt line to power supply and the power supply zero volt, in turn to be connected to chassis at the input socket of the amplifier only (Please note only one point earthing is alone allowed to avoid hum loop etc).

  25. Seetharaman, what is the replacement for 2.7 ohms resistor

    • Greenaum

      A 1.2 + 1.5 in series? I dunno, what resistors can you get?

    • Greenaum

      Actually it shouldn’t matter. I’m assuming it’s a high-pass filter. Just use something around 2.7. 3 or 4 should be fine.

  26. Seetharaman, i need a tone control circuit for this 100W amplifeir, but the tone control circuit i saw in this site uses +15V -15V power supply. But the 100w amplifeir needs +38V -38V Power supply.. My question is, if I CONNECT THE TONE CONTROL TO THE AMPLIFIER, will the -38V +38V POWER SUPPLY BE TOO MUCH FOR THE TONE CONTROL?

  27. Seetharaman, you said the power supply for this Amplifeir is +38V / -38V to get 100W output,… my Question is how many Ampere of current is needed, i mean, what is the Current Rating of the Transformer and the doide

    • Seetharaman

      Hi Rex the transformer should be 27-0-27 with 150VA rating. Each winding should be capable of 2.5Amp to take care of surge requirement. You can use 3 amp rectifier itself. But I prefer you to use 6A10 6 amp rectifier capable of 400PIV.

  28. sir, I tried both u r 100w circuits (sub woofer also). I would like to install this in my car. 12v to 36v converter smps is pricing too much. pls post a affordable circuit if possible.

  29. please give us the POWER SUPPLY CIRCUIT for this amplifeir

  30. Setharaman, please give us the POWER SUPPLY CIRCUIT for this amplifeir

  31. Hi, ive patched up my circuit but it doesnt work at all, i followed the circuit diagram with all the right components. All the signals at the individual pins are correct, just that there isnt any output signal at pin 14. Couldn’t understand what could be the problem. i connect pin 9 and 10 to 3.5v individually.

    Please do get back to me. Using it for a project.
    Appreciate it alot!
    Thanks!!

    • that because you have to turn it on on pw pin,just connect it to +

  32. Seetharaman, please give us the ‘POWER SUPPLY CIRCUIT’ for this Amplifeir

  33. Seetharaman, thank you for the link you gave to me, for the brigde of this amplifeir, i visited the site but, the bridge amp circuit does not have good explanation and description, and the circuit diagram is not clear enough.. Circuitstoday.com is my best site, i dont like going to other site, please post the bridge amplifeir circuit here

  34. Seetharaman

    Hj Ace 8 ohms 100 watts is sufficient. Still we recommend higher wattage since sudden peak power after a small pass can damage the speaker. If volume level is kept low and operate you can use even lower power speakers, but ensure that you operate at lower volume levels. use a suitable speaker protection like fast acting fuse etc.

    • Hi,if i were to patch up my circuit onto a breadboard first, isit a must to install heatsink onto it too??

      do you have the PCB schematic layout for this circuit?appreciate it alot.

      Thank you!

  35. hi is it a must to use 8OHMS 150W rating speaker? any lower won’t work??

  36. Seetharaman please wire this amp circuit to work with single power supply, please give us the circuit

  37. Seetharaman, is it possible to wire this 100W AMPLIFEIR CIRCUIT to work with a ‘single POWER supply? If yes, please give us the circuit diagram because i dont have center tapped transformer

  38. Please give the BRIDGE AMPLIFEIR Circuit using two of this IC’s TDA7294 as bridge amplifeir circuit with one output

  39. hi sir,can I conect vm/vstby to +25V ct,,coz on my transform 20V not available,,18 and 25…
    So,what I must to do….

    • Seetharaman

      Hi rujtam as per manifacturers datasheet, you may connect it to -Vs or ground hence voltage is not the criteria, it is only what ever you are supplying to the IC as Vs

  40. Which place are we connecting pin 9 and 10 to in this circuit, please explain very well

  41. Hello,
    Will any one help me in changing this circuit to work with 14volts 45 Ampere source i.e car battery?? plz reply

    • Seetharaman

      Hallo 12 volt to plus minus 35 volt switched power supplies are available use one of them.

  42. how do you connect and use vm and v stand by?

  43. Alexander

    Dear sir.
    Can you please get me a power supply circuit for this amplifier
    Thank you.

  44. This circuit very use full .
    Please tell me a tone control for this power amp.
    Thank. U.

  45. Dear sir.
    What are the advantages to use dual power supply

  46. yugandaraj

    HI sir. the supply given is +/- 38 v ,5A, but
    Can i use this circuit at 12V , 12 A ?? does it work ??

  47. Seetharaman

    Hi Mansoor Pin No 9 and 10 should be connected to +20volt for playing and zero for muting or to keep the amplifier on standby.

  48. Tried it, it sounds so awesome, the ic is pretty expensive here though.

  49. Please Explane The Circuites 9 and 10 Pin Connection.

  50. Dear Bro. Seetharam…
    thanx for the advice god bless u
    Ramdas

  51. seetharaman

    Hi Ramdas the recommended operating point of the amplifier is with plus minus 35 volts DC the power delivered will be 70 Watts RMS into 8 Ohms load with a distortion of 0.5% for plus minus 35 volts DC you have use a transformer with a rating of 25-0-25 volts @ 3 to 4 amps per channel.

  52. What is the actual watts of this TDA7294 amplifier

  53. Dear Sir….

    How much ampere required for driving one channel of TDA7294
    Pls specify the Transformer details and Power supply details

    pls reply to my mail

  54. seetharaman

    Hi Alex the absolute maximum voltage allowed is + & – 40volts with 30 volts transformer you will get 42 volts. The recommended voltage for 8 ohms speaker safe operation is 25 – 0 – 25volt 3 to 4 amps transformer.

  55. can i use 30v 3 amp transformer for this circuit

  56. Nikit thacker

    can we implement this circuit on zero pcb?

  57. seetharaman

    Hi You can build this logic, in sequence, in discrete digital ICs and connect the output through proper interface (drivers) to the individual equipment.

    • Santhosh

      Hi Seetharaman,

      I tried building this amp and was successful. only when I try to install volume pot, since the first pin of the pot is connected to the chasis ground. I get a ground loop hum. If I connect the source directly to the amp there is no hum.

      Please suggest on how to connect a volume pot.

  58. Hello Sir,
    How do I design a circuit that works when the main power fails On-line UPS starts, after battery gets low then the generator starts automatically untill the battery gets charged. when battery is fully charged the generator stops and power comes from the UPS till the battery goes low, when main supply comes if generator is running it should stop and UPS should charge from the main power supply. is it possible?

    • hello, i need to know how do you make the calculus for choosing the resitences and capacitances for the circuit, please

      • Seetharaman

        Refer manufacturers catalog and application data book.