OPT3101: Internal crosstalk temperature coefficient and phase temperature coefficient

Pengsheng,

  Are you using the EVM or a custome PCB that you have created? If custome what emitter and photodiode are you using?

Gordon：

    I used a new designed PCB ，emitter used SFH 213 FA，photodiode used SFH4550；

Pengsheng,

Have you put these parts into the system estimator to see what it tells you? Are you using any lens' on the photodiode?

http://www.ti.com/tool/OPT3101ESTIMATOR-SW

Gordon：

 It was not tested on simulations and the system did not use lenses；

Pengsheng,

  I ran your photodiode and emitter through the system estimator. It looks like your error and noise will make this system hard to be accurate and function beyond 4m. There are many factors that will allow it to work further such as a brighter reflective surface and assuming a high efficiency of the emitter and photodiode. 

I recommend that you become familiar with the system estimator tool I linked to above. 

SHGT system estimator 2.sdx

I have attached a pre-populated system estimator file with your parts. 

Can you provide some speifications about your system? Min and max distance? Total accuracy? required beam width or total area to measure?