LM4863MX/NOPB Datasheet/PDFLM4863MX/NOPB application field and working principle
The LM4863MX/NOPB is a high-performance, low-power audio power amplifier in the Linear-Amplifiers-Audio family. It is designed to provide up to 1.5W of continuous RMS output power into an 8-Ω impedance loudspeaker. The LM4863MX/NOPB is suitable for a wide variety of applications demanding low-power, high-performance audio power amplification, including self-powered portable audio systems, active loudspeakers, cell phones, portable MP3 players, tablet PCs and personal digital assistants (PDAs). The LM4863MX/NOPB combines a high-performance, differential-input, DC-coupled audio power amplifier with a low-power shutdown mode for system power-down. The device comes in a small 12-terminal thermally enhanced TSSOP package. The LM4863MX/NOPB also features a low-voltage capability, which allows the device to be operated from 3.2V to 5.5V.
In addition to the standard features of the LM4863MX/NOPB, the device also offers a low-power shutdown mode with a low application current (2µA), allowing the device to remain in the shutdown state and have only a small current draw. The LM4863MX/NOPB also offers an internal thermal shutdown/protection feature that automatically shuts down the device when the die temperature exceeds a threshold. This ensures the device will not be damaged due to excessive power dissipation.
Working Principle
The output current of the LM4863MX/NOPB is generated by an internal high gain quasi-complimentary differential input amplifier which drives an external complementary output stage. The output stage is designed to amplify the differential signal between the two inputs to generate an amplified output. The current output from the LM4863MX/NOPB is modulated by a pair of low-voltage N-channel enhancement-mode MOSFETs, each connected to one of the amplifier’s input pins. The current gain of the amplifier is determined by the ratio of the source and drain resistance of the MOSFETs.
In addition to its high current-drive capability, the LM4863MX/NOPB is also designed to achieve a high gain-bandwidth product of 5MHz, with low harmonic distortion, independent of supply voltage and temperature. The result is a device capable of producing excellent audio performance with a minimum of external components. It also features a Power Good indication with an internal comparator, a thermal shutdown feature, and an external mute option.
Conclusion
The LM4863MX/NOPB is an ideal solution for applications such as self-powered portable audio systems, active loudspeakers, cell phones, portable MP3 players, tablet PCs and PDAs, offering low power consumption, high current drive capability and excellent audio performance. It combines a high-performance audio power amplifier with a low-power shutdown mode, which enables system designers to conserve battery life. It also offers protection from over and under temperature conditions, as well as an external mute option, to ensure that the audio system is always safe from damage.