Class D Audio Amplifier Application
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Digital Audio Amplifier Requirements
- Reduce the amplifier size
- Increase efficiency
- Increase current capability
- Improve the MosFET thermal efficiency
- Meet EMI regulations
- Better control of current and voltage transients
- Increase amplifier linearity
- Decrease switching times
- Narrow the MosFET parameter distribution
- Reduce system cost
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Why is the DirectFET MOSFET the optimal solution?
- IRF6665 Digital Audio MOSFET combines the latest IR medium voltage trench silicon with the advanced DirectFETTM package
- Key parameters, such as RDS(on), Qg, Qsw, and Qrr are optimized for mid-power Class-D audio amplifier applications
- Lower stray inductance (less ringing and faster switching time) and package resistance
- Excellent heat dissipation
- IRF6665, has all the characteristics to be the best power switch for mid-power amplifiers
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Typical Class D Audio Amplifier Performance using the DirectFET MOSFET
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100W Amplifier without Heatsink
Topology: Half Bridge
IR MOSFET: IRF6665 (datasheet)
Switching frequency: 400KHz
Rated Output Power: 120W x 6CH / 4 ohm
THD: 0.01% @1KHz, Half Power
Frequency Response: 5Hz to 40KHz (-3dB)
Power Supply: ±20V ~ ±35V
Size: 4.0” x 5.5”
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Temperature Performance
1/8 Pout (12.5W/4 W)
Tamb = 25 °C, Test time = steady state
Two channels in operation
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Full Pout (100W/4 W),
Tamb = 25 °C, Test time = 3 minutes
Two channels in operation
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Total Harmonic Distortion + Noise Performance
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120W @THD=1%
170W @THD=10%
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THD=0.01%@50W
S/N=110dB
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Distortion waveforms (200us/div, 500mV/div)
(a) 50W, 1 kHz, THD+N=0.0075%
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(b) 173W, 1 kHz, THD+N=10%
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Efficiency vs. Power (±35V for 4Ω load)
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