TDA2005 Stereo Amplifier

One of the readers has asked me to help them design a stereo amplifier using the TDA2005 audio IC from ST Microelectronics.  Its an all in one integrated stereo amplifier chip.  All a design engineer needs to do is read and understand the datasheet, apply the information and build the circuit!

Here is the datasheet:

TDA2005 datasheet

The device itself is quite popular and has been used in several automotive audio applications and computer speaker systems.  I've seen it and it's variants over the years.

Here is the schematic diagram.  It's taken directly from the datasheet example, I added a volume control dual gang potentiometer and a 1k resistor to the input stage but apart from that it's exactly the same as the example.

The circuit is easy to understand. Most of the work is performed by the circuitry contained within the TDA2005 amplifier. C1 & C2 are input coupling capacitors and block any DC voltage present in the input audio signal.  C10 & C11 are also DC blocking capacitors and C7 & C9 block DC voltage from the feed back loop to the differential inputs of the amplifiers. Resistors R3 and R5 (and R4 and R6) set the level of negative feed back. C10 and R7 (and C11 and R8) provide a high frequency load for stability where the loudspeaker's inductive reactance may become excessive. C4 and C5 provide power supply decoupling or filtering.

The gain is set by the formula 1 + (R3/R5).  So in the case of the above circuit it is:

Av = 1 + (1200 / 33)

Av = 37.36

The gain may be increased by reducing the feedback resistors R5 and R6. A value of 22 ohms would provide a gain of approximately 55. If you need much more than 60x gain, it would be better to use a preamplifier such as the LM386 Ruby amplifier circuit and then amplify it.

The maximum supply voltage for this Kit is 18V and the minimum current is 2A. Check the power supply voltage and current and check the polarity before turning the amplifier on.

Unfortunately there is no spice model available for the TDA2005 circuit so I cannot provide a simulation.  I have not actually built the circuit yet so I also cannot provide a video of it in operation. I have ordered the components however and as soon as I make a PCB I will populate it and post a video of it working.  Here is the PCB layout top and bottom layers:

PCB Top Layer with components

PCB Bottom Layer

Here is the bill of materials:

Part	Value	Description
C1	2.2uF	16V Electrolytic Capacitor
C2	2.2uF	16V Electrolytic Capacitor
C3	10uF	16V Electrolytic Capacitor
C4	100uF	16V Electrolytic Capacitor
C5	100uF	16V Electrolytic Capacitor
C6	220uF	16V Electrolytic Capacitor
C7	220uF	16V Electrolytic Capacitor
C8	2200uF	16V Electrolytic Capacitor
C9	2200uF	16V Electrolytic Capacitor
C10	100nF	50V Ceramic Capacitor
C11	100nF	50V Ceramic Capacitor
C12	100nF	50V Ceramic Capacitor
IC1	TDA2005T	Stereo 10W Power OP AMP
J1	POWER_JACKPTH	DC Power Jack
JP1	Audio Input	3.5mm Audio Jack
JP2	Dual Gang Potentiometer	10k Dual Gang Pot
JP3	Dual Gang Potentiometer	10k Dual Gang Pot
JP4	Speaker Terminals	5mm Screw Terminal
JP5	Speaker Terminals	5mm Screw Terminal
JP6	Alternative DC power input	5mm Screw Terminal
R1	120k	1/4W 5% Carbon Film Resistor
R2	1.2k	1/4W 5% Carbon Film Resistor
R3	33R	1/4W 5% Carbon Film Resistor
R4	1.2k	1/4W 5% Carbon Film Resistor
R5	33R	1/4W 5% Carbon Film Resistor
R6	1R	1/4W 5% Carbon Film Resistor
R7	1R	1/4W 5% Carbon Film Resistor
R8	1k	1/4W 5% Carbon Film Resistor
R9	1k	1/4W 5% Carbon Film Resistor
PCB		PCB to mount components on
Heatsink		Heatsink for TDA2005

Here are some renders of the PCB and what it might look like when populated.  I haven't got a model for the TDA2005 so it doesn't show that part:

 Here is the proof of function!

The maximum amount of output from the amplifier depends upon the supply voltage, current and speaker impedance.  In order to get 10 Watts on each channel the designer must ensure a supply capable of 15 Volts and 2 Amps and a speaker impedance of 1.6 Ohms.  A higher speaker impedance will cause the amplifier to draw more power and not output 10 Watts.  I reckon I'm getting 6 Watts per channel which is more than acceptable for my purposes.... 

Here are the Eagle design files if people wish to make their own:

TDA2005 Eagle Project Files

That's all for now...Enjoy people and take care - Langster!