NS 公司的LM48824是G类参考地立体声耳机放大器,采用NS公司的参考地架构,因此不需要传统耳机放大器所需的大容量的隔直流电容,从而节省了板面积,最小化系统成本. LM48824具有G类省功耗的特性,I2C音量和模式控制,低工作电流和低THD模式,差分输入,可用于手机,PDA,MP3播放器以及手持电子设备和笔记本电脑.本文介绍了LM48824主要指标和特性,以及简单方框图和典型应用电路。

The LM48824 is a Class G, ground-referenced stereo headphone amplifier designed for portable devices. The LM48824 features National’s ground-referenced architecture, which eliminates the large DC blocking capacitors required by traditional headphone amplifiers, saving board space and minimizing system cost.

The LM48824 takes advantage of National’s patent-pending Class G architecture offering power savings compared to a traditional Class AB headphone amplifier. Additionally, output noise is improved by common-mode sensing that corrects for any differences between the amplifier ground and the potential at the headphone return terminal, minimizing noise created by any ground mismatches.

A high output impedance mode allows the LM48824s outputs to be driven by an external source without degrading the signal.

Other features include flexible power supply requirements, differential inputs for improved noise rejection, a low power (2.5μA) shutdown mode, and a 32-step I2C volume control with mute function.

The LM48824s superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM48824 is available in an ultra-small 16-bump, 0.4mm pitch micro SMD package (1.69mm x 1.69mm)

LM48824主要指标:

Quiescent Power Supply Current at 3.6V 0.9mA (typ)

Output Power/channel at VDD = 3.6V RL = 16Ω, THD+N ≤ 1% 37mW (typ)

Output Power/channel at VDD = 3.6V RL = 32Ω, THD+N ≤ 1% 29mW (typ)

PSRR at 217Hz 100dB (typ)

Shutdown current 2.5μA (typ)

LM48824主要特性:

Class G Power Savings

Ground Referenced Headphone Outputs – Eliminates Output Coupling Capacitors

Common-Mode Sense

I2C Volume and Mode Control

High Output Impedance in Shutdown

Differential Inputs

Advanced Click-and-Pop Suppression

Low Supply Current

Low THD mode option

LM48824应用:

Mobile Phones, PDAs, MP3 Players

Portable Electronic Devices, Notebook PCs

图1.LM48824简化方框图