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FT2850 G类单通道功放

2022-3-5 09:53:22 4042 功放

0 GENERAL DESCRIPtiON The ft2850 is a 5W Dual-PumpTM Class-AB/D/G audio power amplifier with automatic level control (ALC) for portable audio applications. It integrates Class-AB and Class-D audio power amplifiers with a Class-G charge pump regulator based upon proprietary Dual-PumpTM topology. It operates from 3.3V to 5.3V supply. With a supply voltage at 4.2V, it can deliver an output power of 5.4W with 10% THD+N, or 4.5W with 1% THD+N, into a 4Ω speaker load. In ft2850, the power supply rail of the audio amplifier’s output stage is adaptively boosted and regulated by a Class-G charge pump regulator, allowing much higher audio loudness than a stand-alone one directly connected to the battery. The adaptive nature of the Class-G charge pump regulator, whose output voltage varies dynamically in response to the level of the audio output, improves overall power efficiency and extends battery life when playing music. The higher output power and greater power efficiency resulted from the Class-G charge pump regulator make ft2850 an ideal audio solution for battery-powered electronic devices. To facilitate various applications, the ft2850 provides three types of audio amplifier outputs, i.e., Class-AB, Class-D, and Class-G. For typical applications, the Class-G/D audio output is preferred for its high efficiency. The Class-AB audio output can be chosen to alleviate design complexities for applications where minimum FM radio interference is required. The ft2850 features ALC that constantly monitors and safeguards the audio output against the boosted supply voltage, preventing output clipping distortion, excessive power dissipation, or speaker over-load. Once an over-level condition is detected, the ALC lowers the voltage gain of the audio amplifier proportionally to limit the peak audio output voltage. FEATURES  Wide range of supply voltages from 3.3V to 5.3V  Proprietary Dual-PumpTM topology  Selectable types of audio outputs: Class-AB/D/G  Filterless Class-D audio amplifier integrated with a Class-G charge pump regulator  Automatic level control to eliminate output clipping  Selectable ALC dynamic characteristics  Maximum output power (Non-ALC Mode) 6.2W (VDD=4.2V, THD+N=10%, RL=3Ω+33µH) 5.4W (VDD=4.2V, THD+N=10%, RL=4Ω+33µH) 3.2W (VDD=4.2V, THD+N=10%, RL=8Ω+33µH)  ALC output power (ALC Mode) 5.0W (VDD=4.2V, THD+N=0.6%, RL=3Ω+33µH) 4.3W (VDD=4.2V, THD+N=0.6%, RL=4Ω+33µH) 2.4W (VDD=4.2V, THD+N=0.6%, RL=8Ω+33µH)  Maximum Voltage Gain: 28dB  ALC dynamic range: 9dB  Low quiescent current: 4.5mA @ VDD=3.7V  Low THD+N: 0.04% (VDD=3.7V, f=1kHz, RL=4Ω+33µH, Po=0.5W)  High PSRR: 68dB at 1kHz  Selectable fade-in time  Auto-recovering over-current and thermal-overload protection  Available in TSSOP-20L & QFN4X4-20L packages APPLICATIONS  Blue Tooth Speakers  Smart Speakers  Portable Consumer Electronic Devices TYPICAL APPLICATION CIRCUIT 3
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qiu83 · 2022-3-8 17:01:43 沙发 Ft2850是一个5瓦双泵类-ab/d/g 音频功率放大器，具有自动电平控制(alc) ，适用于便携式音频应用。它集成了 ab 类和 d 类音频功率放大器与 g 类电荷泵调节器基于专有的双泵拓扑。它的电压从3.3 v 到5.3 v。当电源电压为4.2 v 时，输出功率为5.4 w，10% thd + n，或4.5 w，输出功率为1% thd + n，进入4ω 扬声器负载。 ft2850，音频放大器输出级的电源轨由一个 g 类电荷泵调节器自适应增强和调节，允许比直接连接到电池的独立电源更高的音频响度。G 级电荷泵调节器的自适应特性，其输出电压随音频输出水平的变化而动态变化，提高了整体功率效率，并在播放音乐时延长了电池寿命。更高的输出功率和更高的功率效率是由于 g 类电荷泵调节器使 ft2850成为电池供电电子设备的理想音频解决方案。为了方便各种应用，ft2850提供三种类型的音频放大器输出，即类 ab，类 d 和类 g。对于典型的应用，类 g/d 音频输出是的，因为它的高效率。类 ab 音频输出可以选择，以减轻应用程序的设计复杂性，最低调频无线电干扰是必需的。Ft2850的功能 alc，不断监视和保护音频输出，对增加的电源电压，防止输出削波失真，过度功耗，或扬声器过载。一旦检测到过电平条件，alc 按比例降低音频放大器的电压增益，以限制峰值音频输出电压。注意事项 1）注意 PCB 散热，散热面积，打孔等方式提高 PCB 的散热性能； 2）耦合电容的位置，例如 AVDD, CVDD, BYP, PVOUT, and PVDD 这些脚附近的耦合电容，一定要靠近管脚； 3）原理图上加粗部分都是大电流的走线，尽可能短而粗； 4）当单端输入时，尽可能的接地端要接到音源的地，而不是随机或就近接地。 5） Flying 电容 CF1，CF2 以及 PVDD、PVOUT 端的电容，耐压值要 10V 以上。 6）受到寄生感性和负载感性的影响，VOP/VON 在不同条件下存在不同程度的过冲，必须在输出端加如下电路，（R3=4.7Ω，C3=4.7nF） 7）输出端加磁珠能进一步抑制 EMI，磁珠电流建议 2A 以上，对地电容建议在 330pF~1nF.

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