tlv320aic3101 pga 旁路 削顶

你好！我在用tlv320aic3101 芯片。希望使用pga旁路功能，给芯片输入1k，500mv的正弦波，在差分输出HPLOUT 和HPLCOM处测量输出，HPLOUT处没有偏置电压，频率是1k的，但是波形不对，如附件所示；HPLCOM有2v多的偏置，频率也是1k的，但是波形是正弦波下半部分的一部分；当正弦波的幅度降为240mv左右时，HPLOUT输出是一个1k的正弦波，而HPLCOM则几乎测不到信号。请问，pga旁路出来的波形是否跟输入一样，pga该如何配置？

以下是部分是我的pga通路配置

aic3x_write(codec, 0x08, 0xc0);//master
 aic3x_write(codec, 0x12, 0xf0); //18 right adc gain control   MIC2R/LINE2R is connected to right-ADC PGA.
 aic3x_write(codec, 0x16, 0x7c);//LINE1R is not connected to the right-ADC PGA.  Right-ADC channel is powered up.
 aic3x_write(codec, 0x10, 0x00);//The right ADC PGA is not muted.  gain=0db
 aic3x_write(codec, 0x18, 0x78);//LINE1L is not connected to the right-ADC PGA.

 //aic3x_write(codec, 91, 0x80); //91
 aic3x_write(codec, 0x38, 0x80); //56PGA_R is routed to HPLCOM.
 aic3x_write(codec, 0x33, 0x09);//HPLOUT is not muted.   HPLOUT is fully powered up.
 aic3x_write(codec, 0x31, 0x80); //49
 aic3x_write(codec, 0x3a, 0x09); //58 hplcom enalbe

主时钟12mhz，采样时钟8k，都没有问题。

Hi Mario:

  I answer your question as following:

Q1.HPLOUT处没有偏置电压，频率是1k的，但是波形不对，如附件所示;

A1: From the attached picture, The prob is AC coupling, please set it to DC coupling to check it again.

Q2:当正弦波的幅度降为240mv左右时，HPLOUT输出是一个1k的正弦波，而HPLCOM则几乎测不到信号。请问，pga旁路出来的波形是否跟输入一样，pga该如何配置？

A2: The PGA setting from the attached code works fine at our EVM, please check if there is any problem in the SCH. Also you can try following command to test it again:

w 0x30 0x07 0x80 // SW reset

w 0x30 0x12 0xF0 // MIC2R/LINE2R is connected to PGA_R.

w 0x30 0x10 0x00 // Set PGA_R gain to 0dB

w 0x30 0x31 0x80 // PGA_R is routed to HPLOUT

w 0x30 0x33 0x0D //power on HPLOUT and set gain to 0dB

w 0x30 0x25 0x00 // HPLCOM is configured as differential of HPLOUT

B&R

Fabian