SLOA326 October 2022 TAS2781
The TAS2781 and TAS2783 (hereafter termed TAS278x when interchangeable in this application note) have an internal Hybrid-Pro algorithm allowing users to optimize the efficiency in the system by controlling the external power supply with just enough margin to provide high dynamic range with low distortion.
Features of Hybrid-Pro control:
The Hybrid-Pro boost controller generates a PWM signal at the PWM_CTRL pin with a duty cycle proportional to the peak voltage at the speaker. The signal is converted to an analog voltage to control boost converter feedback (FB) input using an external low-pass filter as shown in Figure 2-1 (see Section 3.1 for details).
By default, the PWM_CTRL pin is configured in an open drain. This configuration allows an easy implementation of a multichannel control loop using a common low-pass filter (LPF). Multiple TAS278x devices can be connected to the same LPF. One pullup resistor is needed between the common connection of the pins and IOVDD rail (see Figure 2-2).
When only one amplifier is driving the LPF, program the PWM_CTRL pin as a push-pull driver. This helps to improve efficiency and reduce one of the external components.