TDA7293 Stereo Amplifier: 2x 100W Configuration with PCB Design

 

Introducing a high-quality audio solution: a stereo amplifier using the TDA7293 IC, capable of producing output up to 2x 100 Watts. This article will discuss the circuit diagram along with the recommended PCB design.

Key Features:

1. Integrated power supply - only requires an external transformer
2. Compact single-sided PCB design
3. Superior sound quality
4. Versatile for various audio applications

Safety Features:

• Mute/stand-by circuit to avoid 'clicks' during power on/off
• No output relay required

Transformer Recommendations:

• Range: 18-0-18V to 33-0-33V
• Power: 200VA
• Note: Lower voltage may require less current

PCB LAYOUT

Part	Value	Description	Quantitity
Capasitors
C1, C4, C8, C13, C16, C20	100nF/100v	Ceramic Capacitor	6
C2, C23	1µF/63V	Polyester Capacitor	2
C3, C5, C6, C17	22µF/63V	Electrolytic capacitor	4
C7, C19	47µF/63V	Electrolytic capacitor	2
C9, C11	10.000µF/63V	Electrolytic capacitor	2
C21, C22	220p/100V	Ceramic Capacitor	2
Semiconductors
D1	1N4148	Diode	1
IC1	TDA7293, TDA7294 or TDa7295, or TDA7296	Audio amplifier integrated circuit	2
B1	GBJ3510, GBJ2510 or equivalent	Bridge rectifier	1
LED1, LED2	Led 5MM	Red LED or color of your choice	2
Resistors
R1, R2, R7R10, R11	22K	Red, red, orange, gold	4
R3, R13	680	Blue, gray, brown, gold	2
R4	33k	Orange, orange, orange, gold	1
R5	10k	Brown, black, orange, gold	1
R6, R12	2,7 ohm 1 Watt	Red, violet, gold, gold	2
R8, R9	4,7K	Yellow, violet, red, gold	2
R14, R15	1,8K	Brown, black, red, gold	2
Miscellaneous
CN1	LIN	Jst Xh 2-Way Connector 2.54 mm pitch or equivalent	1
CN2	RIN	Jst Xh 2-Way Connector 2.54 mm pitch or equivalent	1
CN3	AC	Terminal block 3 pin 5.08 mm	1
CN4	OUTL	Terminal block 2 pin 5.08 mm	1
CN5	OUTR	Terminal block 2 pin 5.08 mm	1

 

Assembly Warning: Insulate the IC body from the heatsink using a mica or plastic thermal pad.

Circuit Analysis:

1. High-Pass Filter (C2, C23, R1, R10):
   • Influences low frequencies
   • Cut-off frequency varies based on capacitor value: 470nF: ~15Hz 1μF: ~7Hz 2.2μF: ~3.2Hz
   • Formula: f = 1/(2ΠRC)
2. Low-Pass Filter (R15/C21, R4/C22):
   • Prevents high-frequency signals
   • Default cut-off: ~400 KHz
   • Adjustable by changing component values
   • Formula same as high-pass filter
3. Mute Circuit (C5, C6, R5, R7):
   • Reduces 'pop' during power on/off
   • Sets switching time constant
4. Gain Settings (R11-R13, R2-R3):
   • Default configuration: 30 dB
   • Can be modified (ensure R11-R2 = R13-R3)
5. Input Impedance: Determined by R1-R10
6. Zobel Network (R6-C4, R12-C16):
   • Prevents oscillation from speaker wire parasitic induction
   • Filters radio interference
7. Additional Capacitors:
   • C7, C19: DC decoupling of feedback
   • C3, C17: Bootstrapping (different position for TDA7293)

By understanding each section of this circuit, you can optimize the amplifier's performance according to your specific audio project requirements.