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PGA309+XTR117 calibration with 3 temperature have a strange issue

user561103
Prodigy 50 points
Other Parts Discussed in Thread: PGA309EVM-USB, PGA309

The schematic  is similar to http://www.ti.com/lit/df/tidr225/tidr225.pdf  .

3 temperature ：-20,25,70

When my sensor's offset ≤±5mV/V and span  =20mV/V ,after calibrated ,the result  is well.4mA and 20mA output error bouth ≤0.2%FS  when the temperature is -20,25,70 .

But my sensor's offset ≤±5mV/V and span =30mV/V ,after calibrated ,4mA  output error  is well.20mA output error is close to 0.5%FS(19.920mA) when tempreture is 25.if I only write one tempreture(-20 or 25 or 70) data to EEPROM,the output is well(error ≤0.1%FS,-0.016mA~+0.016mA) when the product in Corresponding tempreature.

I try to use 4 tempreature(-20,0,25,70 or -20,25,50,70) to calibrate my product,but the result is same:20mA output error is close to 0.5%FS(19.920mA) when tempreture is 25.

Please give me some suggestion,thank you.

Best regards.

  • 0
    TI__Mastermind 27715 points

    Hello,

    What method are you using for calibration - the PGA309EVM-USB software or a system of your own design? If you are using the EVM software, please send me your Model File and Pre-Cal file, as there are multiple settings I can check to help find the root cause of this issue. 

    Do you see this same result on multiple systems, or only on one system?

    Best regards,

    Ian Williams
    Linear Applications Engineer
    Precision Analog - Op Amps

  • 0 in reply to Ian Williams
    Prodigy 50 points

    Hi,

    Both  the PGA309EVM-USB software (not PGA309 multiple system)and my own system is the same result.

    I upload the modle files,pre-cal files ,eeprom files and my own calibrate data(all data in a access file).

    Best regards,

     

    Ping Yan:yan_13@126.com

  • 0 in reply to user561103
    Prodigy 50 points

    The files upload failed.

    8780.20141023.mdb

    2678.600ITEST_MN_1_SN_1_DC_4314.txt 
    [General Info]
Date=2014-10-27
Time=13:48
[Paths]
Model path="/C/Program Files/proj_PGA309EVM-USB/Model_Files/600ITEST.txt"
Pre-Cal path="/C/Program Files/proj_PGA309EVM-USB/Pre_Cal_Files/Iout.txt"
Sensor Emulator path="<Not A Path>"
[EEPROM Data]
Addr0=21577
Addr2=0
Addr4=0
Addr6=1280
Addr8=8735
Addr10=0
Addr12=5135
Addr14=28808
Addr16=10164
Addr18=15408
Addr20=39206
Addr22=10349
Addr24=65404
Addr26=64888
Addr28=10534
Addr30=65400
Addr32=64937
Addr34=10721
Addr36=65400
Addr38=64989
Addr40=10908
Addr42=65395
Addr44=65034
Addr46=11095
Addr48=65391
Addr50=65078
Addr52=11284
Addr54=65392
Addr56=65123
Addr58=11473
Addr60=65388
Addr62=65165
Addr64=11663
Addr66=65386
Addr68=65208
Addr70=11853
Addr72=65382
Addr74=65245
Addr76=12045
Addr78=65382
Addr80=65286
Addr82=12237
Addr84=65377
Addr86=65325
Addr88=12430
Addr90=65376
Addr92=65361
Addr94=12623
Addr96=65372
Addr98=65397
Addr100=12817
Addr102=65370
Addr104=65434
Addr106=13012
Addr108=65368
Addr110=65470
Addr112=13208
Addr114=65367
Addr116=65504
Addr118=32767
Addr120=0
Addr122=49440

    6242.Iout.txt 
    [PGA309_Settings]
Numb Reg=3
Poly Order=2
Output Mode=2
Vout_High_Target=4.000000
Vout_Low_Target=0.800000
Vs=5.000000
Vref=4.096000
Reg0=0
Reg1=0
Reg2=0
Reg3=1280
Reg4=0
Reg5=0
Reg6=5135
Reg7=0
Reg8=0
Temp0=30.000000
Temp1=-20.000000
Temp2=70.000000
XTR_R1=10000.000000
XTR_R2=10000.000000
XTR_R_ref=191000.000000
XTR_Vref=0.000000
Iout_Low_Target=0.004000
Iout_High_Target=0.020000
Use Sensor Emulator=TRUE
Calibrate Nonlin=FALSE
Temp3=30.000000

    2677.600ITEST.txt 
    [Filenames]
Pre-Cal Filename=Iout.txt
Sensor Emulator Filename=""
[Misc]
Comments=""
Serial No=2
Model No=1
Model ID=600ITEST
Use Sensor Emulator=FALSE