These higher-channel-count systems in an infotainment system may integrate:
High channel count systems in these infotainment systems may integrate:
A center speaker.
Center speaker. Separate tweeter/midrange/woofer speakers.
Separate tweeter/midrange/woofer. Instrument cluster chimes or warning tones.
Dashboard beeps or beeps. Additional speakers to communicate information, such as warning drivers to take control of steering or braking if the vehicle is operating in a semi-autonomous driving mode.
Other speakers can transmit information, such as warning the driver to take control of the steering wheel or brakes when the vehicle is in semi-autonomous driving mode. Some higher-end car models may actually have as many as 20 speakers. The speakers in these audio systems are driven by an external amplifier typically placed near the trunk of the car. These audio systems also incorporate more advanced sound algorithms such as active noise cancellation to deliver a more personalized audio experience.

Some high-end car models may actually have as many as 20 speakers. The speakers in these audio systems are driven by external amplifiers usually mounted near the trunk of the car. These audio systems also include more advanced sound algorithms, such as Active Noise Cancellation, which can provide a more personalized sound experience.

With each subsequent model year, automakers are adding more and more electronics. Coupled with the need to drive six to eight speakers directly from the infotainment system, space behind the dashboard is now at an all-time premium. Therefore, it's becoming a priority for audio hardware designers to develop smaller automotive audio amplifier solutions with lower heat dissipation. In this paper, I'll describe four factors that drive overall audio amplifier size:

With each subsequent model year, automakers are adding more and more electronics. Combined with the need to drive six to eight speakers directly from the infotainment system, the space behind the dash is now better than ever. Therefore, designers of audio hardware should start by developing small automotive audio amplifier solutions with lower heat dissipation. In this article, I will describe the four factors that drive an overall audio amplifier:
Efficiency/thermal performance.
Efficiency/thermal performance. Switching frequency.
On-off level. Inductor size.
Inductor size. Package design.
Package Design. Efficiency/thermal performance
Efficiency/Thermal Performance

Designers have traditionally designed car radios using Class-AB linear audio amplifiers. Class-AB linear amplification is drastically less efficient than the newer but well-established Class-D switching technology. Figure 1 highlights the difference.
Traditionally, designers have used class AB linear audio amplifiers to design car radios. Class AB linear amplification technology is nowhere near as efficient as the new, but fairly mature, class D switching technology. Figure 1 highlights the difference.

Class-AB efficiency loss leads directly to additional internal heat generation, which then requires dissipation outside the audio amplifier. The need for a larger heat sink in Class-AB designs also exacerbates the challenge to continuously reduce the overall automotive audio amplifier system solution size.

Class AB efficiency losses directly lead to additional heat generation inside, which then needs to be dissipated outside the audio amplifier. This also makes it more difficult to consistently reduce the size of the overall car audio amplifier system solution due to the need for larger heat sinks in Class AB designs.

Class-D amplifiers can achieve the same output power but dissipate significantly less heat, enabling designers to use a much smaller and less complex heat sink to transport dissipated power to the ambient environment.

Class D amplifiers can achieve the same output power but with significantly less heat dissipation, which allows designers to use smaller, simpler heat sinks to transfer heat to the surrounding environment.

Switching frequency
On-off level

The number of electronics mounted behind the dashboard in a relatively tight space increases the possibility that circuits can emit interfering signals in close proximity. Ultimately, modern radios and audio amplifiers must provide better immunity from electromagnetic interference (EMI) in the AM band to meet these challenges.

The amount of electronics installed in the relatively small space behind the dash increases the likelihood that the circuit can emit interfering signals at close range. What's more, modern radios and audio amplifiers must provide better immunity to electromagnetic interference (EMI) in the AM band to meet these challenges.

In the US, AM radio stations broadcast in the 535-kHz to 1705-kHz frequency band. Existing Class-D audio amplifier designs typically operate with a fundamental switching frequency in the 400-kHz to 500-kHz range. These lowers-witching- frequency Class-D amplifier designs create harmonics that occur directly within the AM band, as shown in Figure 2.

American AM radio stations have a band range of 535-kHz to 1705-kHz. Existing Class D audio amplifier designs typically operate at fundamental switching frequencies in the 400 kHz to 500 kHz range. These low switching frequency Class D amplifier designs generate harmonics directly in the AM band, as shown in Figure 2.

The harmonics create interfering signals that reduce the sensitivity of the AM receiver, thereby hindering AM radio station reception. Implementing an AM avoidance scheme on Class-D amplifier designs mitigates the effects of these harmonics.

Harmonics create interfering signals that desensitize AM receivers, preventing AM radio stations from receiving them. Applying AM avoidance techniques to Class D amplifier designs can mitigate the effects of these harmonics.

Class-D audio amplifiers require reconstruction filters to convert the pulse-width modulation (PWM) signal from the amplifier output into the desired analog audio signal. These output filters are made with inductors (L) and capacitors (C) (as shown in Figure 3) for a typical bridge-tied load (BTL) amplifier circuit, and help minimize EMI from the highspeed switching transients on the output stages of Class-D amplifiers.

Class D audio amplifiers require reconstruction filters to convert the pulse width modulation (PWM) signal output by the amplifier into the desired analog audio signal. These output filters consist of inductors (L) and capacitors (C) (shown in Figure 3) and are used in a typical bridge-tied-load (BTL) amplifier circuit, and are designed to minimize the impact on the output stage of a Class D amplifier. High-speed switching transient EMI.

Automotive Class-D audio amplifiers that operate at a 2.1-MHz switching frequency provide significant margin above the AM band, as shown in Figure 4. This design is free of any lower-frequency spikes that would interfere with the AM band, thus eliminating the need for an AM avoidance scheme.

An automotive Class-D audio amplifier operating at a 2.1-MHz switching frequency provides significant headroom above the AM band, as shown in Figure 4. This design does not have any low frequency spikes that would interfere with the AM band, thus eliminating the need for AM avoidance techniques.

As an additional benefit, a 2.1-MHz switching frequency enables a lower inductance value for the output filter due to the inherent reduction in ripple current. A lower inductance for an equivalent current rating leads to a smaller inductor, reducing printed circuit board (PCB) area and subsequently the EMI footprint.

Another benefit is that the 2.1-MHz switching frequency allows lower inductance values for the output filter due to the inherent reduction in ripple current. The low inductance of the equivalent current rating results in a smaller inductance, which reduces the printed circuit board (PCB) area and subsequently reduces the EMI footprint.

Inductor size
Inductor size
For Class-D automotive audio amplifiers, the value of the inductor required in the LC filter to ensure the proper PWM demodulation filter characteristic depends on the switching frequency. As shown in Figure 5, a 400-kHz automotive audio amplifier typically uses either a 10 -μH or 8.2-μH inductor value, while a 2.1-MHz higher-switching-frequency amplifier design can take advantage of a much smaller and lighter-weight inductor in the range of 3.3 μH to 3.6 μH (assuming that each amplifier provides the same output power).

For class D automotive audio amplifiers, the required inductor value for the LC filter (to ensure proper PWM demodulation filter characteristics) depends on the switching frequency. As shown in Figure 5, 400-kHz car audio amplifiers typically use 10-µH or 8.2-µH inductor values, while 2.1-MHz high switching frequency amplifier designs can utilize smaller and lighter inductors in the 3.3µH to 3.6µH range ( Assuming each amplifier provides the same output power).

As I mentioned earlier, a typical car radio design has at least four channels to drive two front speakers and two rear speakers. This simple configuration requires eight inductors for a Class-D automotive audio amplifier, since each channel requires two inductors, as shown earlier in Figure 3. Thus, the size of each inductor is multiplied by 8, which is a significant contribution to overall PCB size and design weight. As a general reference, the transition from 8.2-μH inductors to 3.3-μH inductors can save over 85 % in inductor space on the PCB and over 85% in weight.

As mentioned earlier, a typical car radio design has at least 4 channels to drive 2 front speakers and 2 rear speakers. This simple configuration requires 8 inductors for a Class D car audio amplifier since 2 inductors are required per channel, as shown in Figure 3. Therefore, the size of each inductor multiplied by 8 has a significant impact on the overall PCB size and design weight. In general, switching from 8.2-µH inductors to 3.3-µH inductors can save more than 85 percent of the inductor space and weight on the board by more than 85 percent.

Package design
Package Design

Another audio amplifier consideration that can greatly contribute to the overall system solution size of an automobile's infotainment system is the design of the amplifier package.

Another audio amplifier consideration that can greatly reduce the size of the overall system solution in an automotive infotainment system is the design of the amplifier package.

A square-shaped package design has inputs on the bottom of the package and two audio outputs with LC filters orthogonally placed on either side of the amplifier. As you can see in Figure 6, this type of package design greatly contributes to the overall PCB footprint .
The square package design has inputs at the bottom of the package, as well as two audio outputs, and the LC filters are placed orthogonally to one side of the amplifier. As shown in Figure 6, this type of package design greatly increases the overall PCB footprint.

A better option is a rectangular package that has a “flowthrough” audio signal design. Figure 7 illustrates how the analog input signals come into the amplifier on one side of the chip; amplification of the audio signal takes place on the opposite side of the amplifier , where the signals are then delivered into external output filters.

A square package with a "streaming" audio signal design is a better choice. Figure 7 illustrates how the analog input signal enters the amplifier on one side of the chip; amplification of the audio signal occurs on the other side of the amplifier, and the signal is then passed to an external output filter.

The TPA6304-Q1 audio amplifier uses a 2.1-MHz highswitching-frequency Class-D amplifier technology that features TI Burr-Brown 8482 ; technology. By combining 3.3-μH metal alloy inductors and a flow-through package design, the TPA6304-Q1 delivers a four-channel automotive Class-D amplifier solution size that measures only 17 mm by 16 mm. See Figure 8.

The TPA6304-Q1 audio amplifier uses 2.1-MHz high switching frequency Class D amplifier technology with TI Burr-Brown™ technology. The TPA6304-Q1 combines a 3.3-μH metal alloy inductor with a DC package design to provide a 4-channel automotive Class-D amplifier solution that measures only 17 mm x 16 mm. See Figure 8.

The TPA6304-

Q1, including all of the passive electronic components for the full system solution implementation, is even smaller than the traditional Class-AB amplifier by itself, as shown in Figure 9.

The TPA6304-Q1 (including all passive electronic components for the overall system solution) is smaller than a conventional Class AB amplifier, as shown in Figure 9.

Conclusion
in conclusion

The more electronics added to a car, the more the overall heat signature increases in an already tightly confined space behind the dashboard. Thus, the challenge for automotive audio hardware designers is to implement smaller and smaller audio solutions with lower and lower heat dissipation. Audio amplifier efficiency will only become more important in the future of infotainment system design.

The more electronics installed in a car, the higher the overall heat in the tight space behind the dashboard. Therefore, the challenge for car audio hardware designers is to achieve smaller audio solutions with less heat dissipation. The efficiency of audio amplifiers will only become more important in future infotainment system designs.
The TPA6304-Q1 makes replacing a Class-AB automotive audio amplifier easy. Its 2.1-MHz switching frequency and tiny system solution size allow you to achieve Class-D efficiency at a Class-AB system cost.
The TPA6304-Q1 can easily replace a Class AB car audio amplifier. The TPA6304-Q1's 2.1-MHz switching frequency and small system solution size allow you to achieve Class D efficiency at a Class AB system cost.