National's New Cellular Boomer Amps

National Semiconductor jus let us know about the LM4894 and LM4895 Boomer audio amplifiers for the cellular phone market. National says that Improved PSRR performance reduces the effect of noise on power supply lines being picked up and intensified by the audio amplifier. As a result, there is less noise to the earpiece speaker in cellular phone applications. Higher PSRR also eliminates the need for additional components to condition the power supply lines. The LM4894 and LM4895 are designed for use in cellular phones, PDAs and other portable electronic devices. With the input terminated with a 10 ohm resistive load, the LM4894/95 deliver 80dB PSRR at 217Hz at 3V. With the input un-terminated (floating), the LM4894/95 deliver 87dB PSRR at 217Hz at 3V. They also deliver 50dB of CMRR (common mode rejection ratio). An additional feature of the LM4894 and LM4895 is the selectable shutdown mode. This allows designers to select either shutdown logic high or shutdown logic low. The LM4894/95 does its best to save power by operating at a low supply voltage (3V), while providing sufficient output power (350mW, 8 ohms,