Audio-capable portable devices (such as portable media players, multimedia phones) require long audio playback time, that is, long battery life. To make the battery life of portable devices long, on the one hand to improve the quality of batteries, more importantly, the power consumption of components used in portable devices should be low. The battery life of portable devices is a function of system power and audio codec (CODEC) power and can be expressed as:
Where K is a factor related to battery capacity, battery voltage and power converter efficiency, A is system power consumption, and B is audio CODEC power consumption. In order to maintain the battery life under the premise of small and thin form factor, it is required that all components in the power and audio signal paths must reduce power consumption.
To this end, Wolfson Microelectronics (Wolfson Microelectronics) launched a new generation of ultra-low-power audio CODEC WM8905, which greatly reduces the battery life of audio-capable portable devices, extending audio playback time up to 40 hours.
WM8903 ultra low power CODEC
The WM8903 function block diagram is shown in Figure 1, and its features are as follows:
Figure 1 WM8903 functional block diagram
· SmartDACTM technology-this is a unique low-power DAC switch architecture, the power consumption of DAC to headphones is only 4.4 milliwatts, and the ability to adjust the "performance and output power" curve by programming allows system designers to optimize Usage (in different states such as connected or mobile).
· Class W amplifier technology—Adopt an adaptive dual-drive charge pump and DC servo chip architecture. Class W headphone amplifiers can intelligently track actual music signal levels and use an adaptive dual-driver charge pump to optimize power consumption. This architecture not only optimizes power consumption, but also does not require large DC blocking headphone capacitors, which greatly saves PCB space and BOM of the audio subsystem. With improved bass response, audio performance can be improved.
SilentSwitchTM technology-This technology minimizes "pops & clik" (sounding of loudspeakers on the speaker) by integrating complex clamping and sequencer circuits.
· Dynamic range controller—Using a “fast-release†impulse noise filter, in the presence of loud impulse noise, can improve the resolution of the recorded sound and optimize the recorded sound quality.
· Control sequencer—The sequencer with programmable delay time can turn on / off multiple units of WM8903, which can significantly reduce the “pop†and simplify the software driver development time.
Digital microphone interface-This interface can provide higher SNR (signal to noise ratio) and improve sensitivity matching.
application
WM8903 is designed to significantly extend the playback time of audio-capable portable devices. It is mainly used in portable audio applications, including PMP / MP3 players, multimedia phones, handheld game systems, digital video cameras, and recorders. Figure 2 shows the application of WM8903 in a portable media player.
Figure 2 Block diagram of portable media player
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