Audio

Selection and Solution Guides

Application Notes

Multi-Device Configuration for TPA32xx Amplifiers

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The TPA324x and TPA325x family of parts (TPA3244, TPA3245, TPA3250, TPA3251, and TPA3255) comes equipped with functionality to simplify systems with multiple Class-D amplifiers. Class-D amplifiers use pulse-width modulation (PWM) switching (450 kHz – 600 kHz), which are discrete packets of energy, to deliver large amounts of power with very high efficiency. However, issues can arise if multiple Class-D amplifiers switch simultaneously, but are not synchronized and managed. Issues include:

• Power Supply Overloading resulting from all amplifiers switching on the same edge, causing the supply to droop or sag below the regulated voltage.

• Beat Interference or Beat Tones can occur, which are audible tones caused by two close, but slightly off, switching frequencies interacting to create another frequency.

The oscillator sync pins allow multiple devices to share a common clock and draw power on different phases to improve performance. Different phases reduce power supply loading during the switch cycles. Sharing a clock improves performance by preventing beat tones.

The Clip/OTW and FAULT signal lines are configured so multiple lines can be tied together to simplify circuitry. While not required, these functionalities have several benefits that can simplify circuitry and improve the performance of your audio system.