Audio device with integrated switching power supply
An integrated audio device, such as, for example, a table-top radio, including a housing, a speaker disposed within the housing, a switching power supply disposed within the housing, and audio circuitry disposed within the housing and coupled between the digital switching power supply and the speaker.
1. An integrated audio device comprising:
a housing;
a speaker disposed within the housing;
a switching power supply disposed within the housing;
audio circuitry disposed within the housing and coupled between the switching power supply and the speaker;
a filter circuit disposed within the housing and constructed and arranged to receive an AC input power signal for the audio device and to produce a filtered signal; and
an input power line that carries the AC input power signal, the input power line configured as an FM antenna for the audio device.
2. The integrated audio device of claim 1 , wherein the switching power supply is a digital switching power supply.
3. The integrated audio device of claim 2 , wherein the digital switching power supply comprises a switching controller and a transformer wound in accordance with a specification of the switching controller.
4. The integrated audio device of claim 1 , further comprising:
a bridge rectifier coupled to the filter circuit and configured to receive and rectify the filtered signal and to provide a DC signal to the switching power supply.
5. The integrated audio device of claim 4 , wherein the switching power supply comprises a transformer and a plurality of digital switches configured to generate an AC signal from the DC signal.
6. The integrated audio device of claim 4 , wherein the filter circuit comprises a line filter.
7. The integrated audio device of claim 6 , wherein the line filter comprises a transformer.
8. The integrated audio device of claim 6 , wherein the filter circuit further comprises at least one inductor coupled between the line filter and the bridge rectifier.
9. The integrated audio device of claim 8 , wherein the filter circuit further comprises at least one capacitor coupled between an output line of the filter circuit and ground.
10. The integrated audio device of claim 1 , further comprising an electromagnetic shield disposed within the housing.
11. The integrated audio device of claim 10 , wherein the electromagnetic shield comprises a faraday cage that encloses the switching power supply.
12. The integrated audio device of claim 10 , wherein the audio circuitry comprises a digital amplifier, and wherein the electromagnetic shield comprises:
a first metal box substantially enclosing the switching power supply; and
a second metal box substantially enclosing the digital amplifier;
wherein the first and second metal boxes are coupled to ground.
13. The integrated audio device of claim 1 , wherein the integrated audio device has a total internal volume of approximately 273 cubic inches.
14. The integrated audio device of claim 1 , wherein the integrated audio device is configured to generate approximately 100 Watts RMS output power.
15. The integrated audio device of claim 1 , wherein the integrated audio device is a table-top radio.
16. The integrated audio device of claim 1 , further comprising an FM receiver circuit coupled to the input power line.