安森美(On Semi)公司的 NCP2991是1.35W具有可選擇快速開通時間的音頻功率放大器,電源5.0V時可向8歐姆BTL負載提供連續(xù)輸出功率1.35W,3.6V電源時可向4.0歐姆BTL負載提供1.1W. NCP2991的工作電壓從2.5V到5.5V,PSRR可高達-100dB,關斷模式的超低功耗為10nA,主要用在手提電子設備,PDA和無線手機.本文介紹了NCP2991的主要特性, 單端輸入和差分輸入的音頻放大器應用電路以及演示板電路圖與材料清單(BOM).

NCP2991 1.35 Watt Audio Power Amplifier with Selectable Fast Turn On Time
The NCP2991 is an audio power amplifier designed for portable communication device applications such as mobile phone applications. The NCP2991 is capable of delivering 1.35 W of continuous average power to an 8.0__ BTL load from a 5.0 V power supply, and 1.1 W to a 4.0 _ BTL load from a 3.6 V power supply.

The NCP2991 provides high quality audio while requiring few external components and minimal power consumption. It features a low−power consumption shutdown mode, which is achieved by driving the SHUTDOWN pin with logic low.
The NCP2991 contains circuitry to prevent from “pop and click” noise that would otherwise occur during turn−on and turn−off transitions. It is a zero pop noise device when a single ended or a differential audio input is used.

For maximum flexibility, the NCP2991 provides an externally controlled gain (with resistors). In addition, it integrates 2 different Turn On times (15 ms or 30 ms) adjustable with the TON pin. Due to its superior PSRR, it can be directly connected to the

battery, saving the use of an LDO. This device is available in a 9−Pin Flip−Chip CSP (Lead−Free).
NCP2991主要特性:
1.35 W to an 8.0 _ BTL Load from a 5.0 V Power Supply
Best−in−Class PSRR: up to −100 dB, Direct Connection to the Battery
Zero Pop Noise Signature with a Single Ended Audio Input
Ultra Low Current Shutdown Mode: 10 nA
2.5 V−5.5 V Operation
External Gain Configuration Capability
External Turn−on Time Configuration Capability: 15 ms or 30 ms
Thermal Overload Protection Circuitry
This is a Pb−Free Device*
NCP2991典型應用:
Portable Electronic Devices
PDAs
Wireless Phones



圖1.單端輸入音頻放大器應用電路



圖2.差分輸入音頻放大器應用電路



圖3.NCP2991演示板電路圖

NCP2991演示板材料清單(BOM):