LM4587_声音处理.pdf

LM4857 Stereo 1.2W Audio Sub-system with 3D Enhancement General Description The LM4857 is an integrated audio sub-system designed for stereo cell phone applications. Operating on a 3.3V supply, it combines a stereo speaker amplifier delivering 495mW per channel into an 8? load, a stereo headphone amplifier de- livering 33mW per channel into a 32? load, a mono earpiece amplifier delivering 43mW into a 32? load, and a line output for an external powered handsfree speaker. It integrates the audio amplifiers, volume control, mixer, power management control, and National 3D enhancement all into a single pack- age. In addition, the LM4857 routes and mixes the stereo and mono inputs into 16 distinct output modes. The LM4857 is controlled through an I2C compatible interface. Other fea- tures include an ultra-low current shutdown mode and ther- mal shutdown protection. Boomer audio power amplifiers are designed specifically to provide high quality output power with a minimal amount of external components. The LM4857 is available in a 30-bump ITL package and a 28–lead LLP package. Key Specifications j POUT, Stereo Loudspeakers, 8?, 5V, 1% THD+N 1.2W (typ) j POUT, Stereo Headphones, 32?, 5V, 1% THD+N 75mW (typ) j POUT, Mono Earpiece, 32?, 5V, 1% THD+N 100mW (typ) j POUT, Stereo Loudspeakers, 8?, 3.3V, 1% THD+N 495mW (typ) j POUT, Stereo Headphones, 32?, 3.3V, 1% THD+N 33mW (typ) j POUT, Mono Earpiece, 32?, 3.3V, 1% THD+N 43mW (typ) j Shutdown Current 0.06μA (typ) Features n Stereo speaker amplifier n Stereo headphone amplifier n Mono earpiece amplifier n Mono Line Output for external handsfree carkit n Independent Left, Right, and Mono volume controls n National 3D enhancement n I2C compatible interface n Ultra low shutdown current n Click and Pop Suppression circuit n 16 distinct output modes n Thermal Shutdown Protection n Available in micro SMD and LLP packages Applications n Cell Phones n PDAs n Portable Gaming Devices n Internet Appliances n Portable DVD/CD/AAC/MP3 player