The Type TDA1521 from Valvo/Mullard is an integrated HiFi stereo power amplifier designed for mains fed applications such as stereo TV. The device works optimally when fed from a ? 16 V supply, and delivers a maximum output power of 2 x 12 W into 8 Q. The gain of the amplifiers is fixed internally at 30 dB with a spread of 0.2 dB to ensure optimum gain balance between the channels.
Integrated Stereo Amplifier Circuit Diagram:
A special feature of the chip is its built-in mute circuit, which disconnects the non-inverting inputs when the supply voltage is less than ± 6 V, a level at which the amplifiers are still correctly biased. This arrangement ensures the absence of unwanted clicks and other noise when the amplifier is switched on or off. The TDA1521 is protected against output short circuits and thermal overloading. The SIL9 package should be bolted onto a heatsink with a thermal resistance of no more than 3.3 K/W (RL = 852; Vs = ± 16 V; Pd =14.6 W; Ta = 65 °C). Note that the metal tab on the chip package is internally connected to pin 5. The accompanying photograph shows that this high quality stereo amplifier has a very low component count, and is readily constructed on a piece of Veroboard.
The following technical data are stated as typical in the datasheets for the TDA1521 (RL=852; Vs = ? 16 V):
- Distortion at P°=12 W: 0.5%
- Quiescent current: 40 mA
- Gain balance: 0.2 dB
- Supply ripple rejection: 60 dB
- Channel separation: 70 dB
- Output offset voltage: 20 mV
- 3 dB power bandwidth: 20-20,000 Hz
