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LOG114:Log114 problem

Part Number: LOG114

1. There is a route with a small input current, about 100pA--100nA, I2 is the reference current (set to 2.8nA), the input part of the circuit is as shown below, and the output is AD-converted.

The problem I encountered was that the AD value of this road was unstable and the jump value was quite large. (Exclude the AD problem because the other roads are stable). My analysis may have problems with the I2 setting. Do you have any other suggestions?

2. Some of the Log114 data sheets (page 16) are not fully understood. The first question is related to this part. Can you translate the 16th page into Chinese for me? Or help me translate the paragraph marked. I didn't understand what it meant, thank you!

  • Hello Meng,

    The LOG114 developes very high transimpedance gains and is easy to end up with less than optimal performance. PC board layout, board cleanliness, and noise ingress (especially 50/60 Hz) from external sources can all degrade the performance. The lower the input current levels the more easily it is to corrupt them. You may find that you will need to ultrasonically clean the PC board in DI water, at least two times, to remove any residual solder flux. The input wires leading into the LOG114 may need to be shielded, the PC board may need to be put in a shielded enclosure, and any power wires coming to the board may need to be shielded to prevent ac pick-up.

    Regarding translation of the LOG114 datasheet into Chinese (Mandarin), try the TI.com.cn URL. Also, I found this web page in Chiense and it does have some links to the LOG114:

    http://www.ti.com.cn/analog/cn/docs/analogtechdoc_hh.tsp?viewType=mostuseful&rootFamilyId=0&familyId=2&docCategoryId=5&litCount=all

    Regards, Thomas

    Precision Applications Engineering