TDA7294S_05 Datasheet, PDF (10/16 Pages) STMicroelectronics – 100V - 100W DMOS AUDIO AMPLIFIER WITH MUTE/ST-BY

TDA7294S
5.2 BRIDGE APPLICATION
Another application suggestion is the BRIDGE configuration, where two TDA7294S are used. In this ap-
plication, 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 150W, while with Rl=16 Ohm, Vs =
±40V the maximum Pout is 200W (Music Power).
6 APPLICATION NOTE: (ref. fig. 10)
6.1 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 together.
■ The master chip connections are the same as the normal single ones.
■ The outputs can be connected together without the need of any ballast resistance.
■ The slave SGND pin must be tied to the negative supply.
■ The slave ST-BY pin must be connected to ST-BY pin.
■ The bootstrap lines must be connected together and the bootstrap capacitor must be increased: for N
devices the boostrap capacitor must be 22µF times N.
■ The slave Mute and IN-pins must be grounded.
6.2 THE BOOTSTRAP CAPACITOR
For compatibility purpose with the previous devices 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 boot-
strap 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 bootstrap 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 boot-
strap 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 positive supply (V_S -3 to 6V)
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