The difference between tda7293 and tda7294

ST's new high-power DMOS power amplifier IC TDA7294, with its high power, complete protection functions, and a very good dull tone, is loved by the majority of audio enthusiasts and has become an audio power amplifier IC in audio DIYERs at home and abroad. ST's first choice, and then STMicroelectronics has launched TDA7293 with better performance and power. In addition to the increase in power, it can be seen from the official information that the conversion rate of TDA7293 is also 10V/us, but there are more Wide voltage power supply range, up to dual 50V DC power supply, which means that it has a larger dynamic range and higher output power than TDA7294. It can reach 100W average output power when dual 40V DC power supply and 8 ohm load. Of course, if the voltage is increased to double 50V, or a smaller load such as 4 ohms, there will be greater output power. According to the characteristics of TDA7293, when selecting a transformer, double 28V AC voltage can be selected, so that the filtered voltage is rectified It is about double 40V. Of course, the voltage can also be increased. Considering that the grid voltage has a fluctuation, it is better to be a few volts less than the maximum voltage of 50V, which is beneficial to the stable operation of the circuit.

TDA7293 performance parameters

Power supply voltage (dual power supply): ±12±50±60V

Output power: Vs=±45VR=8Ω140w

Open loop voltage gain: 80dB

Conversion rate: 15v/μS

Output current: 6.5A

Input impedance: 100120150KΩ

Single row dual row (MulTIwatt15) 15-pin package. Operating voltage range: ±12V—±60V; peak output current 10A; output power: 100W at ±40V, 8Ω; 140W at ±45V, 8Ω; 100W at ±29V, 4Ω; total harmonic distortion (Po=5W, f= 1KHz) 0.005%; conversion rate 15V/μs (TDA7294 is 10V/μs, the higher the conversion rate, the richer the sound quality level); input impedance 100KΩ; frequency response 20Hz-20Kz; working in Class A and B status.

The internal structure of TDA7293 is divided into three stages: the differential input stage is composed of bipolar transistors, and the driving stage and power output stage use field effect transistors. This structure can integrate the low noise of bipolar transistors and the linearity and temperature coefficient of power field effect transistors. , The advantage in tone. The sound is beautiful, taking into account the advantages of bipolar signal processing circuit and MOS power tube, it has the advantages of low distortion, low noise, high withstand voltage, mute switch, overheat protection, short circuit protection, etc.

TDA7293 pins and functions

Pin 1 is the standby ground;

Pin 2 is the inverting input terminal;

Pin 3 is the positive phase input terminal;

4 feet are ground;

Pin 5 is the short-circuit current detection terminal, usually as floating;

6 feet is the bootstrap end;

Pin 7 is the positive power input terminal (signal processing part);

Pin 8 is the negative power input terminal (signal processing part);

Pin 9 is the standby end;

Pin 10 is the mute end;

11 is the buffer drive output terminal (used when bridging);

Pin 12 is the feedback input terminal;

Pin 13 is the positive power input terminal (part of the power output stage);

Pin 14 is the power output terminal;

Pin 15 is the negative power input terminal (part of the power output stage)

tda7293 circuit diagram

Figure 1 is the circuit schematic diagram of the current negative feedback constant current power amplifier using TDA7293 (only one channel is drawn in the picture, and the other channel is the same). The current negative feedback is adopted, which also includes the speaker system in the feedback network. , Plays a positive role in the control of the speaker, effectively offsets the distortion caused by the vibration of the speaker, significantly enhances the bounce of the music, makes the rigid sound in a single plane sound field become lively, and enhances the sense of space. The width and depth of the sound field have been significantly improved.

In order to solve the dryness and hairiness of digital music from digital audio sources (such as CD, VCD, DVD, etc.), the circuit in Figure 1 has a softening effect on digital sounds, and can soften the forward "fuzzy" sound of digital audio sources. Turn the hard sound into music. The function is that cf1 and cf2 in the circuit in Figure 1 are high-frequency AC gain compensation networks, which are used to reduce digital sound (compress high-frequency overtones above 60-80KHz) Or weaken). IC2 in the picture is DC servo function.

Purpose of component selection: good circuit design plus the selection of high-quality components can exert its effect to the highest limit! ①WIMAMKP polypropylene non-inductive capacitor for signal coupling; ②The resistor adopts imported metal film low-noise precision (±1%) five-color ring resistor, and its noise is very low; ③The non-polar capacitor adopts Japanese Panasonic metallized non-inductive CBB capacitor and MKP Polypropylene non-inductive capacitor; ④The circuit board adopts silver-plated glass fiber epoxy board (the benefits of silver plating: prevent oxidation, reduce solder joint resistance, and help improve the analysis of small signals), printed with high-grade blue oil change;.

Application of assembled power amplifier: The circuit in Figure 1 is a dual-channel power-free part (the schematic diagram of the power part is very simple, not drawn here). The advantage of this is that it improves the signal-to-noise ratio of the left and right channels, and the assembly When the power amplifier is combined, the power supply can be far away to reduce the AC interference, so that a good power amplifier can be made. At this time, a suitable solution for AV and Hi-Fi is recommended: virtual Dolby surround sound processing circuit QS7779→BBE circuit (BA3884)→tone circuit (ME-128 or KA-307 Class A pre-stage or SP-27 or LM4610N) → power amplifier board, plus 400W double 26V ring cow. ▲When assembling, pay attention to the grounding method and the input ground and output ground must be separated to the power ground before they can be connected.

Main features of TDA7294

■Wide power supply voltage range: ±10V ~ ±40V

■High output power: 70W (up to 100W)

■Standby and mute function

■No noise ON/OFF switch

■Low noise and low distortion

■Short circuit protection and overheat protection

DA7294 pin and function

Pin 1 is the standby end;

Pin 2 is the inverting input terminal;

Pin 3 is the positive phase input terminal;

4 feet are grounded;

5, 11, and 12 feet are empty;

6 feet is the bootstrap end;

Pin 7 is +Vs (signal processing part);

Pin 8 is -Vs (signal processing part);

9 feet are standby feet;

10 feet are silent feet;

13 feet are +Vs (last stage);

Pin 14 is the output terminal;

15 feet are -Vs (last stage).

tda7294 circuit diagram

The OCL circuit diagram is shown in Figure 1. This circuit is a dual-channel 70W power amplifier composed of two TDA7294. There are few external components and simple circuit. When the power supply voltage is ±35V, 70W continuous output power can be obtained on an 8 ohm load. It is very suitable for playback in an environment below 30 square meters. If the speaker impedance is less than 8 ohms, the power supply voltage should be reduced accordingly.