Low-power amplifiers with electronic control

There is some European commercial organization, which is called Philips. It produces all sorts of fun chips, and about two of them, we will discuss. The first is TDA8551. This chip is bridgeable amplifier with output power of 1 watt at power supply voltage of 5 V. thus, the supply current in silent mode is 10 mA. The chip is made in 8-pin package and does not require a radiator that can be used in various small-sized devices. The chip is equipped with overheating protection, has an internal delay circuit load connection - so when you switch, you will not hear wheezing, Pookie, and other wonderful music transients. Well, another advantage which had been provided for this chip - electronic volume control. It's all in words, words - see diagram:


So that's a modest scheme, requiring mainly shunt capacitors and not in large quantities. The S1 and S2 buttons to adjust the volume, switch SW1 - mode amplifier. I must say that the selected volume level is maintained as long as the chip is not physically be selected food. From STANDBY mode, it will come with the loudness with which you left before entering this mode. If you pull out the power at all, then in the next match, the chip starts with the position of the volume control, the appropriate gain level is -20 dB. The plate with the elements:

The symbol in the diagram is the Value

C1 - MF

C2 - 0,33

C3 - 0,1

C4 - 0,1

C5 - MF

R1 2.2 kω

DA1 - TDA8551

The second chip is actually twice the previous copy. This is TDA8552. In one case this chip contains two identical amplifiers. The only difference is that with a bit more output power of 1.4 W per channel. But, nevertheless, it does not require a radiator and can be used anywhere. Scheme include the following:


This chip is another difference is the presence of the output number 4. This conclusion allows you to control the connection of headphones (of course, with the right of the connector) and automatically reduce the output power and power from a power source current. But, in the diagram I drew - will send you to the site, and we will become very lazy.

The symbol in the diagram is the Value

C1 - 0,33

C2 - 0,33

C3 - 0,1

C4 - 0,1

C5 - MF

C6 - MF

C7 - MF

C8 - MF

C9 - 0,1

R1 2.2 kω

R2 2.2 kω

R3 - 1K

R4 - 1K

DA1 - TDA8552