NS 公司的LM48824是G類參考地立體聲耳機放大器,采用NS公司的參考地架構,因此不需要傳統耳機放大器所需的大容量的隔直流電容,從而節省了板面積,最小化系統成本. LM48824具有G類省功耗的特性,I2C音量和模式控制,低工作電流和低THD模式,差分輸入,可用于手機,PDA,MP3播放器以及手持電子設備和筆記本電腦.本文介紹了LM48824主要指標和特性,以及簡單方框圖和典型應用電路。
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主要指標:
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應用:
Mobile Phones, PDAs, MP3 Players
Portable Electronic Devices, Notebook PCs
 圖1.LM48824簡化方框圖
圖2.LM48824典型應用框圖 |
