基于Maxim MAX13335E/MAX13336E的汽车高保真立体声音频输入方案

Maxim公司的MAX13335E/MAX13336E是用于汽车的高保真立体声音频输入放大器，具有双路低噪音可编增益放大器，采用全差分（7VRMS）和准差分（3.5VRMS）输入信号以及通过I2C接口控制的诊断功能，工作电压3.3V或5V，28V到-16V容差输入，共模输入-5V到+11.5V，主要用在汽车无线电前置单元，RSA/RSE，连接模块和汽车远程信息处理。本文介绍了MAX13335E/MAX13336E主要优势和特性，框图和应用电路，以及评估板MAX13335E EVK主要特性，电路图，材料清单和PCB设计图。

The MAX13335E/MAX13336E are high-fidelity stereo audio input amplifiers designed for automotive applica­tions requiring audio-level detection and/or jack sensing capability. The devices feature a dual-channel， low-noise， program­mable gain amplifier that accepts fully differential and quasi-differential input signals with diagnostics capability controlled through an I2C interface. The devices’audio receiver can also pair with the MAX13325/MAX13326 audio transmitter to form a complete differential audio link in automotive systems.

Each channel of the device features high common-mode rejection ratio （CMRR） （80dB）， enabling the recovery of audio signals in the presence of large common-mode noise in automotive environments. An integrated pro­grammable gain amplifier is adjustable from -14dB to +16dB （MAX13335E） and -22dB to +8dB （MAX13336E） with zero-crossing detection to provide an optimum out­put-signal level and limit zip noise. The external flexible diagnostic inputs can be configured to perform jack sense functions or to detect short-to-battery， short-to-ground， open load， and shorts between channels.

The audio inputs are protected against ISO 10605 ±15kV Air Gap and ±8kV Contact Discharge ESD pulses. Both devices have a -40℃ to +105℃ operating temperature range， and are available in a 16-pin QSOP package.

MAX13335E/MAX13336E主要优势和特性：

+3.3V or +5V Operation

+28V to -16V Tolerant Inputs

Wide Common-Mode Input Range （-5V to +11.5V）

Fully Differential Inputs Up to 7VRMS

Quasi-Differential Inputs Up to 3.5VRMS

Audio Presence Detection

Jack Sense Detection

Diagnostic Capability

Programmable Gain with Zero-Crossing Detection

I2C Control Interface

Automotive Grade ESD Protection

• ISO 10605 ±15kV Air Gap

• ±8kV Contact Discharge

MAX13335E/MAX13336E应用：

Radio Head Units

RSA/RSE

Connectivity Modules

Automotive Telematics

图1.MAX13335E/MAX13336E典型应用框图

图2.MAX13335E/MAX13336E应用电路图（1）

图3.MAX13335E/MAX13336E应用电路图（2）

图4.MAX13335E/MAX13336E应用电路图（3）

评估板MAX13335E EVK

The MAX13335E evaluation kit （EV kit） is a fully assembled and tested PCB that evaluates the MAX13335E automotive audio receiver. The IC features a dual automotive differential audio receiver with I2C control and diagnostics. The EV kit features an on-board microcontroller for communicating with the I2C interface of the device. PCB pads are provided for accessing the analog inputs/outputs and the diagnostic I/O ports.

The EV kit operates from a +3.3V or +5V power supply that provides 100mA of current. The EV kit can also operate from the on-board USB +5V supply. The EV kit delivers the audio outputs with programmable gain between -14dB and +16dB. The EV kit can also evaluate the MAX13336E after IC replacement of U1.

Windows XPM-， Windows VistaM-， and WindowsM 7-compatible software is provided to facilitate configuration. The EV kit software controls the on-board microcontroller over the USB， which generates I2C commands.

评估板MAX13335E EVK主要特性：

S +3.3V or +5V Single-Supply Operation

S Proven Audio PCB Layout

S On-Board USB Interface Circuit Generates I2C-Compatible Signals

S PCB Pads for User-Supplied I2C-Compatible Signals

S Surface-Mount Components

S Evaluates the MAX13336E After IC Replacement

S Windows XP-， Windows Vista-， and Windows 7-Compatible Software

S Fully Assembled and Tested

图5.评估板MAX13335E EVK电路图（1）

图6. 评估板MAX13335E EVK电路图（2）

评估板MAX13335E EVK材料清单：

图7.评估板MAX13335E EVK PVB设计图（1）：左：元件布局;右：元件面走线

图8.评估板MAX13335E EVK PVB设计图（2）：GND层2

图9.评估板MAX13335E EVK PVB设计图（3）：左：PWR层3;右：焊接面