A Few questions in L9780 "Wide range air fuel sensor control interface"

[OSult]

We are developing a system which uses a 

Wide range air fuel sensor control IC "L9780" which is planned to be interfaced to the Bosch LSU4.9 Probe Sensor. We have worked previously with Bosch's CJ125 and planning on going over to use ST's L9780, but we need to fill in the gaps to proceed.

In the datasheet ( the only document available ) The application notes is missing a lot of basic information.

I've contacted ST Microelectronics, but seems they have nothing to help filling the gaps.

I would appreciate if someone would kindly help us out. I'm willing to share more information if desired. My questions so far are as follows :

1-   No details on how to calculate the Nernst cell impedance from the RCT2 amplifier readings

2-   No information about the how the impedance measurement is used in the heater PID control program

More to come later if we can find an expert to answer or application notes.

Regards

Sultan

[Nrose.1]

Did you ever get answers to this ? im looking for the same

[OSult]

no

[wliao.11]

• How to calculate the internal resistance for L9780, why to get two AD values in the output register to calculate the internal resistance does not match the actual

[ISyro.1]

They gave me several documents. One contains the formula for internal resistance calculation. Another contains information that Bosh sensor pump-current has mismuch with its specification. Now I made a board and installed it to real engine with LSU 4.9. This bundle is working, I used it to regulate fuel mixture as by narrow band sensor. The pump-current of my LSU 4.9 on open air is about 10 mA, not like in its specification. I don't know how accurate is this bundle. Will watch. Actually, my sensor was bought as Bosch 0258017025.

[wliao.11]

Thanks,I got the mail.This email means a lot to me. At 2021-08-12 17:16:13, "ST Community" wrote: ISyro.1 (Community Member) posted a file. L9780_Bosch setup Proposal 16-03-11 Download (pdf) or reply to this email Replying to OSult (Community Member) asked a question. Edited Monday, September 17, 2018 2:30 PM A Few questions in L9780 "Wide range air fuel sensor control interface" We are developing a system which uses a Wide range air fuel sensor control IC "L9780" which is planned to be interfaced to the Bosch LSU4.9 Probe Sensor. We have worked previously with Bosch's CJ125 and planning on going over to use ST's L9780, but we need to fill in the gaps to proceed. In the datasheet ( the only document available ) The application notes is missing a lot of basic information. I've contacted ST Microelectronics, but seems they have nothing to help filling the gaps. I would appreciate if someone would kindly help us out. I'm willing to share more information if desired. My questions so far are as follows : 1- No details on how to calculate the Nernst cell impedance from the RCT2 amplifier readings 2- No information about the how the impedance measurement is used in the heater PID control program More to come later if we can find an expert to answer or application notes. Regards Sultan ISyro.1 (Community Member) posted a file. L9780_Bosch setup Proposal 16-03-11 Download (pdf) Thursday, August 12, 2021 2:16 AM You're receiving emails when someone "Comments after me." To change or turn off ST Community email, log in as struct.mcu@163.com.st. Are notifications about this post getting annoying? Reply to this email with the word " mute ". STMicroelectronics N.V.

[SUC0]

I'd like to dust off the subject. We have exactly the same problem of going from CJ125 to STM L9780. Is there a way to know the resistivity of the trimming resistor without going through a hand measurement (multimeter?).

In the field this does not seem feasible and we did not have the constraint of knowing the TAG resistor with the CJ125.

We need some support to integrate properly the STM solution with a Bosch Lambda LSU 4.9.

Thanks in advance for your help,

BR