安森美NCP2991音频功率放大方案

安森美(On Semi)公司的NCP2991是设计用于手提通信设备如手机等的音频功率放大器.电压5V时,能向8欧姆负载提供1.35W的连续平均功率, 电压3.6V时, NCP2991能向4欧姆负载提供1.1W的连续平均功率.关断模式的电流只有10nA,可用于手提电子设备,PDA以及无线手机等.本文介绍了NCP2991的主要特性, 输入差分放大应用电路图和单端输入放大应用电路图,以及NCP2991演示板电路图和材料清单.

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 ohm BTL load from a 5.0 V power supply, and 1.1 W to a 4.0 ohm 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典型应用:
Portable Electronic Devices
PDAs
Wireless Phones



图1.NCP2991单端输入差分放大应用电路图



图2.NCP2991差分输入音频放大应用电路图



图3.NCP2991演示板电路图
演示板材料清单



图4. NCP2991单端配置图



图5.NCP2991差分配置图