8.2.2.1 Hardware and Software Design

• Step 1: Hardware Schematic Design: Using the Typical Application Schematic as a guide, integrate the hardware into the system schematic.
• Step 2: Following the recommended layout guidelines, integrate the device and its supporting components into the system PCB file.
• Step 3: Thermal Design: The device has an exposed thermal pad which requires proper soldering. For more information, see the Semiconductor and IC Package Thermal Metrics , SPRA953, and the PowerPAD Thermally Enhanced Package, SLMA002G, application reports.
• Step 4: Develop software: The EVM User's Guide has detailed instructions for how to set up the device, interpret diagnostic information, and so forth. For information about control registers, see the Table 7 section.
• For questions and support go to the E2E forums.

8.2.2.2 Parallel Operation (PBTL)

The device can drive more current by paralleling BTL channels on the load side of the LC output filter. Parallel operation requires identical I²C settings for any two paralleled channels in order to have reliable system performance and even power dissipation on multiple channels. For smooth power up, power down, and mute operation, the same control commands (such as mute, play, Hi-Z, and so on) should be sent to the paralleled channels at the same time. The device also supports load diagnostics for parallel connection. There is no support for paralleling on the device side of the LC output filter, which can result in device failure. When paralleling channels, use the parallel BTL I²C control bits in register 0x0D. Parallel channels 1 and 2, and/or channels 3 and 4. Setting these bits allows the thermal foldback to react on both channels equally. Provide the audio input to channel 2 if paralleing channels 1 and 2, and channel 3 if paralleling channels 3 and 4.

8.2.2.3 Input Filter Design

For the TAS5414C device, the IN_M pin should have an impedance to GND that is equivalent to the parallel combination of the input impedances of all IN_P channels combined, including any source impedance from the previous stage in the system design. For example, if each of the four IN_P channels have a 1-µF dc blocking capacitor, 1 kΩ of series resistance due to an input RC filter, and 1 kΩ of source resistance from the DAC supplying the audio signal, then the IN_M channel should have a 4-µF capacitor in series with a 500-Ω resistor to GND (4 × 1 µF in parallel = 4 µF; 4 × 2 kΩ in parallel = 500 Ω).

8.2.2.4 Amplifier Output Filtering

The output FETs drive the amplifier outputs in an H-bridge configuration. These transistors are either fully off or on. The result is a square-wave output signal with a duty cycle that is proportional to the amplitude of the audio signal. The amplifier outputs require a low-pass filter to filter out the PWM modulation carrier frequency. People frequently call this filter the L-C filter, due to the presence of an inductive element L and a capacitive element C to make up the 2-pole low-pass filter. The L-C filter attenuates the carrier frequency, reducing electromagnetic emissions and smoothing the current waveform which the load draws from the power supply. See the Class-D LC Filter Design application report, SLOA119 , for a detailed description on proper component selection and design of an L-C filter based upon the desired load and response.

8.2.2.5 Line Driver Applications

In many audio applications, the end user would like to use the same head unit to drive either a speaker (with several ohms of impedance) or an external amplifier (with several kilohms of impedance). The design is capable of supporting both applications; however, the one must design the output filter and system to handle the expected output load conditions.