Problem about CJ120

[Ben_pvbj]

Hi ,all
now I am to complete the oxygen percent measurement employing the cj120 chip . I notice that in its CJ120_Product_Info the chip present volt UR to calculate the internal Ri basing on the Rcal about 82.5 ohm , but I dont know how to get the precise value of Ri, is there any famulation about that? I made the Ri always arroud 120 ohm , it couldn't reach the value 80 of 780 .

another question is how to use the UA to calculate the lambda value , I made the Ip value with the equation Ip=(UA-1.50)/(61.9*17) but how do I get the lambda value , looking up the table ,but where to get the lambda-IP table? Or is there any other ways to get the lambda because I noticed that they present a formulation between the XO2 % and the lambda =(XO2 /3+1)/(1-4.76*XO2 ).

[ralphj1]

Do you have any CJ125 documentation besides the product information data sheet that can be downloaded from the Bosch website? I have a CJ125 extended technical summary but it is unfortunately written in German.

[Ben_pvbj]

Do you have any CJ125 documentation besides the product information data sheet that can be downloaded from the Bosch website? I have a CJ125 extended technical summary but it is unfortunately written in German.

No ,I haven't any documentation about cj125 other than the data sheet of cj120 . I have no idea about how to calculate the lambda and the Ri basing on the value the chips support.