Design of dual-channel power amplifier circuit based on TDA1514

This article introduces two TD1514A amplifier circuits designed by Philips for digital audio as the dual-channel amplifier circuit of this Hi-Fi combination (as shown in the figure below, the other channel is omitted in the figure, and the other channel is the same as the figure). TDA1514A has a large output power: Pout = 50W (VP = ±27.5V), a high conversion speed: 15V/μs, an excellent signal-to-noise ratio of 85dB, ripple suppression of 75dB, THD—0.08%, and an operating voltage of TDA1514A: ±9—±30V. The TDA1514A circuit has waiting and mute states, overheat protection, short circuit protection, power tube safe working area protection, and electrostatic discharge protection. Low offset voltage, high ripple suppression, and extremely low thermal resistance.

As we all know, many amplifiers have a power of about 100W×2, but when used in homes, the volume is usually only turned up to about 1/5-1/4, that is, only about 10-30W of power. If the volume is turned up too high, your ears will suffer, and the speakers will not be able to stand it and the music will be distorted. Therefore, for a home of several dozen square meters, it is most suitable to have audio equipment with a "golden power" of about 30W.

Application circuit diagram 5 features: constant current negative feedback and DC servo system (the main circuit of the DC servo circuit is used to accurately correct the drift of the DC potential output by the TDA1514A circuit after the DC-blocking capacitor to the ground of the negative feedback is cancelled). The linear element resistor RA (0.5Ω2W) samples the current flowing through the speaker voice coil and feeds it back to the input of the power amplifier, so that the amplifier drives the load in a fixed current mode, and the speaker oscillates under the control of the current to make sounds. The characteristic is that when the playback frequency reaches the low frequency and near the resonance peak, the constant current circuit enhances the bass strength and the resolution of the treble, making the playback tone of the entire system sound full, thick, clear and bright, with the charm of a tube power amplifier.