NS 公司的LM49153是全集成音頻子系統，包括高效25mW的G類耳機放大器(THD+N ≤ 1%)和高效的1.35W D類揚聲器放大器(RL = 8Ω, THD+N < 1%)，通過I2C進行音量，模式選擇和關斷控制，主要用在手機和智能手機。本文介紹了LM49153主要指標，主要特性，典型音頻放大器應用電路以及演示板電路圖和材料清單，元件布局圖。

　　The LM49153 is a fully integrated audio subsystem designed for portable handheld applications such as cellular phones.

　　Part of National’s PowerWise family of products, the LM49153 combines an earpiece switch, a high efficiency 25mW class G headphone amplifier, and a high efficiency 1.35W class D loudspeaker into a single device.

　　The headphone amplifiers feature National’s class G ground referenced architecture that creates a ground-referenced output with dynamic supply rails for optimum efficiency. The

　　class D amplifier features an ALC (Automatic Level Control) with a noise gate that provides both no-clip and speaker protection.

　　Mode selection, shutdown control, and volume are controlled through an I2C compatible interface. Click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM49153 is available in an ultra-small 25-bump 0.4mm pitch micro SMD package (2.30mm x 2.42mm).

　　LM49153主要指標：

　　■ Class G Headphone Amplifier,

　　HPVDD = 1.8V, RL = 32Ω

　　IDDQHP 1.2mA (typ)

　　POUT, THD+N ≤ 1% 25mW (typ)

　　HP VOS 0.5mV (typ)

　　■ Mono Class D Speaker Amplifier

　　RL = 8Ω, THD+N < 1%

　　POUT, LSVDD = 5.0V 1.35W (typ)

　　POUT, LSVDD = 3.6V 680mW (typ)

　　Efficiency 88% (typ)

　　LM49153主要特性：

　　■ Class G Ground Referenced Headphone Outputs

　　■ High Efficiency Class D Amplifier with Spread Spectrum

　　■ No Clip

　　■ Speaker Protection

　　■ Noise Gate

　　■ I2C Volume and Mode Control

　　■ Advanced Click-and-Pop Suppression

　　■ Micro-power shutdown

　　LM49153應用：

　　■ Feature phones

　　■ Smart phones

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　　圖1。LM49153典型音頻放大器應用電路

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　　圖2。LM49153演示板電路圖