MAX97220 差分输入的线路/耳机放大器IC性能特征及应用电路介绍

Maxim公司的MAX97220 A/B是差分输入的线路耳机放大器,5V电源时能以3VRMS驱动1K欧姆线路负载, 3.3V电源时能以2VRMS驱动600欧姆线路负载,工作电压2.5V-5.5V, DirectDrive输出,不需要隔直流电容,THD+N优于90dB,18位SNR性能达112dB,主要用于STB,蓝光和DVD播放器,LCD电视和音频设备.本文介绍了MAX97220主要特性, 功能方框图,MAX97220A评估板主要特性,电路图,材料清单和PCB元件布局图.
The MAX97220A/B is a differential input DirectDrive® linedriver/headphone amplifier. This device is capable of driving linelevel loads with 3VRMS into 1kI with a 5V supply and 2VRMS into600I loads from a 3.3V supply. A headphone load is capable of beingdriven with 125mW into 32I with a 5V supply. The IC is offered withan inter­nally fixed 6dB gain or an externally set gain throughexternal resistors. The external gain setting nodes can also beused to configure filters for set-top box applica­tions. The IC hasexceptional THD+N over the full audio bandwidth.
Two versions of the IC are available with different turn-on times(tON). The A and C versions for headphone applications feature atON of 5.5ms while the B and D versions, intended for set-top-boxapplications, feature a 130ms tON. An on-chip charge pump invertsthe power-supply input, creating a negative rail. The output stageof the amplifier is powered between the positive input sup­ply andthe output of the charge pump. The bipolar sup­plies bias theoutput about ground, eliminating the need for large,distortion-introducing output coupling capaci­tors. The IC powerson and off without clicks or pops.
The IC is available in a 3mm x 3mm x 0.8mm, 16-pin TQFN and isspecified over the extended -40NC to +85NC temperature range.

MAX97220主要特性:
Output Power 125mW into 32I with a 5V Supply
3VRMS Output Drive into 1kI with a 5V Supply
2VRMS Output Drive into 600I with a 3.3V Supply
Fully Differential Inputs
Fixed or Externally Adjustable Gain with No Clicks or Pops
Wide 2.5V to 5.5V Operating Range
DirectDrive Outputs Eliminate DC-Blocking Capacitors
Flat THD+N, Better Than 90dB in the Audio Band
18-Bit SNR Performance, 112dB
Footprint Compatible with the MAX9722
Simple Multimedia Interfaces

MAX97220应用:
Set-Top Boxes
Blu-rayK and DVD Players
LCD Televisions
Prosumer Audio Devices

图1.MAX97220功能方框图

图2.MAX97220简化方框图

图3.MAX97220A和MAX9722 PCB布局图

图4.MAX97220A/B增益设定图

MAX97220A评估板
The MAX97220A evaluation kit (EV kit) is a fully assembled andtested circuit board that evaluates the MAX97220A differentialinput DirectDrive® line driver/headphone amplifier. The device iscapable of driving 125mW into 32Ω, or 3V_RMS into 600Ωload, with a 5V supply.
The EV kit provides an externally set gain, is powered from a 2.5Vto 5.5V single power supply, and includes a shutdown input. The EVkit also evaluates the MAX97220B, MAX97220C, and MAX97220D devices.Request a free MAX97220B, MAX97220C, and/or MAX97220D IC samplefrom the factory when ordering the EV kit.

MAX97220A评估板主要特性:
2.5V to 5.5V Single-Supply Operation
3VRMS Output Drive Into 600ω Load
125mW Headphone Amplifier
Fully Differential Inputs
Externally Adjustable Gain
Low-Power Shutdown Input
Evaluates the MAX97220B, MAX97220C, and MAX97220D (with ICReplacement)
Fully Assembled and Tested

图5.MAX97220A评估板电路图
MAX97220A评估板材料清单(BOM):


图6.MAX97220A评估板PCB元件布局图

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