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Lm4651-lm4652: 170 Watt Class D Audio Power Amplifier

LM4651-LM4652: 170 Watt Class D Audio Power Amplifier

The combination of class D amplifier controller LM4651and power MOSFET package LM4652 gives compact and robust high efficiency class D power amplifier solution. This circuit is ideal for car booster amplifier, active speaker/subwofer, home theater, or PC’s multimedia sound system.  The maximum efficiency 85% is obtained at 125W power output condition. The total harmonics distortion is 10% at full power output of 170W. For better fidelity, the THD at 10W is only 0.3% for 10-500Hz input signal driving  4 ohm speaker. The control of this class D amplifier is done by LM4651, and here are the main features of this controller:

•Conventional pulse width modulation.
•Turn-on soft start and under voltage lockout.
•50kHZ to 200kHz switching frequency range.
•Externally controllable switching frequency.
•Integrated error amp and feedback amp.
•15 Lead TO220 isolated package.
•Self checking protection diagnostic.
•Over modulation protection (soft clipping).
•Short circuit current limiting and thermal shutdown protection.

170w power amplifier 25AC6

Click on picture to view full schematic


The power supply voltage cannot exceed (+-) 22V, and also, the output stage will be turned off when the supply voltage drops under 10.5V to prevent under-voltage failure both for the circuit and for the battery (if implemented for car audio application). [Circuit´s schematic diagram source: National Semiconductor Application Notes]

Keywords : LM4651-LM4652:, 170, Watt, Class, D, Audio, Power, Amplifier
Writer : delon  |
8 Feb 2011 Tue   
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