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поискавой системы для электроныых деталей |
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поискавой системы для электроныых деталей |
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TDA7294SV датащи(PDF) 8 Page - STMicroelectronics |
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TDA7294SV датащи(HTML) 8 Page - STMicroelectronics |
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8 / 13 page  The TDA7294S is a monolithic MOS power ampli- fier which can be operated at 90V supply voltage (100V with no signal applied) while delivering out- put currents up to ±6.5 A. This allows the use of this device as a very high power amplifier (up to 100W as peak power with T.H.D.=10 % and Rl = 4 Ohm); the only drawback is the power dissipation, hardly manageable in the above power range. The typical junction-to-case thermal resistance of the TDA7294S is 1 oC/W (max= 1.5 oC/W). To avoid that, in worst case conditions, the chip temperature exceedes 150 oC, the thermal resis- tance of the heatsink must be 0.038 oC/W (@ max ambient temperature of 50 oC). As the above value is pratically unreachable; a high efficiency system is needed in those cases where the continuous RMS output power is higher than 50-60 W. The TDA7294S was designed to work also in higher efficiency way. For this reason there are four power supply pins: two intended for the signal part and two for the power part. T1 and T2 are two power transistors that only operate when the output power reaches a certain threshold (e.g. 20 W). If the output power in- creases, these transistors are switched on during the portion of the signal where more output volt- age swing is needed, thus ”bootstrapping” the power supply pins (#13 and #15). The current generators formed by T4, T7, zener diodes Z1, Z2 and resistors R7,R8 define the minimum drop across the power MOS transistors of the TDA7294S. L1, L2, L3 and the snubbers C9, R1 and C10, R2 stabilize the loops formed by the ”bootstrap” circuits and the output stage of the TDA7294S. By considering again a maximum average output power (music signal) of 20W, in case of the high efficiency application, the thermal resistance value needed from the heatsink is 2.2 oC/W (Vs =±45V and Rl= 8Ohm). All components (TDA7294S and po wer tran- sistors T1 and T2) can be placed on a 1.5 oC/W heatsink, with the power darlingtons electrically insulated from the heatsink. Since the total power dissipation is less than that of a usual class AB amplifier, additional cost sav- ings can be obtained while optimizing the power supply, even with a high heatsink . BRIDGE APPLICATION Another application suggestion is the BRIDGE configuration, where two TDA7294S are used. In this application, the value of the load must not be lower than 8Ohm for dissipation and current capability reasons. A suitable field of application includes HI-FI/TV subwoofers realizations. The main advantages offered by this solution are: - High power performances with limited supply voltage level. - Considerably high output power even with high load values (i.e. 16 Ohm). With Rl= 8 Ohm, Vs = ±25V the maximum output power obtainable is 150 W, while with Rl=16 Ohm, Vs = ±40V the maximum Pout is 200W (Music Power). APPLICATION NOTE: (ref. fig. 7) Modular Application (more Devices in Parallel) The use of the modular application lets very high power be delivered to very low impedance loads. The modular application implies one device to act as a master and the others as slaves. The slave power stages are driven by the master device and work in parallel all together, while the input and the gain stages of the slave device are disabled, the figure below shows the connections required to configure two devices to work to- gether. The master chip connections are the same as the normal single ones. The outputs can be connected together with- out the need of any ballast resistance. The slave SGND pin must be tied to the nega- tive supply. The slave ST-BY pin must be connected to ST-BY pin. The bootstrap lines must be connected to- gether and the bootstrap capacitor must be in- creased: for N devices the boostrap capacitor must be 22 µF times N. The slave Mute and IN-pins must be grounded. THE BOOTSTRAP CAPACITOR For compatibility purpose with the previous de- vices of the family, the boostrap capacitor can be connected both between the bootstrap pin (6) and the output pin (14) or between the boostrap pin (6) and the bootstrap loader pin (12). When the bootcap is connected between pin 6 and 14, the maximum supply voltage in presence of output signal is limited to 80V, due the boot- strap capacitor overvoltage. When the bootcap is connected between pins 6 and 12 the maximum supply voltage extend to the full voltage that the technology can stand: 100V. This is accomplished by the clamp introduced at the bootstrap loader pin (12): this pin follows the output voltage up to 100V and remains clamped at 100V. This feature lets the output voltage swing up to a gate-source voltage from the posi- tive supply (VS -3 to 6V) TDA7294S 8/13 |
Аналогичный номер детали - TDA7294SV |
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Аналогичное описание - TDA7294SV |
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