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What's wrong, ad5755-1's fault pin output low,pls help me

Question asked by Hontel on Mar 16, 2016
Latest reply on Mar 21, 2016 by DRice

hi,

The board is my own design, and  schematic show as the attachment, reference to CN0328.

Now, if set Iout range to 4~20mA, set DACA to  0xFFFF, the output is very low,and the fault pin is low ( LED indicator is lit),I find Vboost value is abput 7.3V.

AVSS:-15V, AVDD:+15V,DVDD::3.3V,AVCC:+5V



part of code is showen as below:

 

SPI2_Init();

AD5755_1_IO_Initialize();

LDAC_LOW;

while(1)

{

  CLEAR_LOW;

  SPI_send_24bit(0,REG_CONTROL,0,0|REG_SOFTWARE|0x555); //Step1£ºreset

  SPI_send_24bit(0,REG_CONTROL,0,0|REG_DCDC_CONTROL|0x4); //AD1,AD0 : 0,0

 

  SPI_send_24bit(0,REG_CONTROL,DACA,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|RANGE_4_20MA);//

  SPI_send_24bit(0,REG_CONTROL,DACB,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|RANGE_4_20MA);

  SPI_send_24bit(0,REG_CONTROL,DACC,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|RANGE_4_20MA);

  SPI_send_24bit(0,REG_CONTROL,DACD,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|RANGE_4_20MA);

 

 

  SPI_send_24bit(0,REG_GAIN_ALL,0,0xFFFF);

  SPI_send_24bit(0,REG_OFFSET_ALL,0,0x8000);

 

 

  SPI_send_24bit(0,REG_DAC_DATA,DACA,0xFFFF);//20mA

  SPI_send_24bit(0,REG_DAC_DATA,DACB,0x7FFF);

  SPI_send_24bit(0,REG_DAC_DATA,DACC,0x1FFF);

  SPI_send_24bit(0,REG_DAC_DATA,DACD,0x5FFF);

// resu = AD5755_1_RecieveCommand(2);

 

  rt_thread_delay(1);

 

  SPI_send_24bit(0,REG_CONTROL,DACA,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|OUT_EN|RANGE_4_20MA); //Step5: Enable OUT_EN

  SPI_send_24bit(0,REG_CONTROL,DACB,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|OUT_EN|RANGE_4_20MA);

  SPI_send_24bit(0,REG_CONTROL,DACC,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|OUT_EN|RANGE_4_20MA);

  SPI_send_24bit(0,REG_CONTROL,DACD,0|REG_DAC_CONTROL|INT_ENABLE|DCDC|OUT_EN|RANGE_4_20MA);

 

 

}

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