Maxim公司的MAX97220 A/B是差分輸入的線路耳機放大器,5V電源時能以3VRMS驅(qū)動1K歐姆線路負載, 3.3V電源時能以2VRMS驅(qū)動600歐姆線路負載,工作電壓2.5V-5.5V, DirectDrive輸出,不需要隔直流電容,THD+N優(yōu)于90dB,18位SNR性能達112dB,主要用于STB,藍光和DVD播放器,LCD電視和音頻設(shè)備.本文介紹了MAX97220主要特性, 功能方框圖, MAX97220A評估板主要特性,電路圖,材料清單和PCB元件布局圖.
The MAX97220A/B is a differential input DirectDrive® line driver/headphone amplifier. This device is capable of driving line level loads with 3VRMS into 1kI with a 5V supply and 2VRMS into 600I loads from a 3.3V supply. A headphone load is capable of being driven with 125mW into 32I with a 5V supply. The IC is offered with an internally fixed 6dB gain or an externally set gain through external resistors. The external gain setting nodes can also be used to configure filters for set-top box applications. The IC has exceptional 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 a tON of 5.5ms while the B and D versions, intended for set-top-box applications, feature a 130ms tON. An on-chip charge pump inverts the power-supply input, creating a negative rail. The output stage of the amplifier is powered between the positive input supply and the output of the charge pump. The bipolar supplies bias the output about ground, eliminating the need for large, distortion-introducing output coupling capacitors. The IC powers on and off without clicks or pops.
The IC is available in a 3mm x 3mm x 0.8mm, 16-pin TQFN and is specified 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應用:
Set-Top Boxes
Blu-rayK and DVD Players
LCD Televisions
Prosumer Audio Devices
圖1.MAX97220功能方框圖
圖2.MAX97220簡化方框圖
圖3.MAX97220A和MAX9722 PCB布局圖
圖4.MAX97220A/B增益設(shè)定圖
MAX97220A評估板
The MAX97220A evaluation kit (EV kit) is a fully assembled and tested circuit board that evaluates the MAX97220A differential input DirectDrive® line driver/headphone amplifier. The device is capable of driving 125mW into 32Ω, or 3VRMS into 600Ω load, with a 5V supply.
The EV kit provides an externally set gain, is powered from a 2.5V to 5.5V single power supply, and includes a shutdown input. The EV kit also evaluates the MAX97220B, MAX97220C, and MAX97220D devices. Request a free MAX97220B, MAX97220C, and/or MAX97220D IC sample from the factory when ordering the EV kit.
MAX97220A評估板主要特性:
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 IC Replacement)
Fully Assembled and Tested
圖5.MAX97220A評估板電路圖
MAX97220A評估板材料清單(BOM):
圖6.MAX97220A評估板PCB元件布局圖
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