LMP91000 circuit design?

Eyup Semsi Yilmaz

Other Parts Discussed in Thread: LMP91000

Hello!

I am working on an oxygen sensor which is alphasense O2-A2. I designed a circuit with lmp91000,but i could not solve sensor reaction time. I mean that, when i start my system,sensor does not start in 6 - 7 minutes. It is always show maximum oxygen concentration, then it is starting decrease slowly to real concentration. But it is showing right concentration after 1 hour!.....

Here is my register configurations;

TIA_Gain = 14K

RLoad = 10R

Ref_Source = internal (Vdd = 5V)

INT_z = 67%

Bias_Gain = positive

Bias = 0%

Fet_Short = Disabled

OP_Mode = 3-lead amperometric cell

On my circuit design;

between C1 and C2 10 pF and 1 Mohm paralel

all grounds connected together

I have tested my i2c communication about writing to lmp91000, and there is no problem.

over 13 years ago

0 Eyup Semsi Yilmaz over 13 years ago

Prodigy 100 points

Hello again!

I solved my problem... Thanks for helps!

0 Jason Seitz over 13 years ago in reply to Eyup Semsi Yilmaz

TI__Intellectual 2630 points

Eyup,

Thats good news. Yes these sensors have a warm up time associated with them but I have not experienced the long delays that you have.

Please share your bug/fix with the community for the public's learning.

0 Eyup Semsi Yilmaz over 13 years ago in reply to Jason Seitz

Prodigy 100 points

Thanks for attention!

Just i added prallel resistor to between sensor's pins.Now it is reacting whenever i execute the system:)

All configurations are same.

0 Vineeth Raj over 13 years ago in reply to Eyup Semsi Yilmaz

Prodigy 20 points

Hi EYUP,

I think I am facing the same problem that you had faced.Can you give me the value of resistance used and between which electrodes you used that resistance?

0 Eyup Semsi Yilmaz over 13 years ago in reply to Vineeth Raj

Prodigy 100 points

I used 47 ohm resistor according to datasheet of sensor. There are two pins on sensor,so i added between them.

0 Vineeth Raj over 13 years ago in reply to Eyup Semsi Yilmaz

Prodigy 20 points

Thank you for your reply EYUP,

In the first post it is mentioned that you configured AFE as 3 lead amperometric.So I expected it is having Counter,Working and Reference.Anyway thank you.

0 Eyup Semsi Yilmaz over 13 years ago in reply to Vineeth Raj

Prodigy 100 points

Yes i used 3 lead amperometric,but i used O2 sensor. Also i used CO sensor which is using that 3 pins(re,ce,we). But you should wait a little with such kind of sensors when it started the system.For example, my CO sensor starting to work in 30 seconds afte the system start. That has written in datasheet of sensor.

0 dave johnson1 over 12 years ago in reply to Eyup Semsi Yilmaz

Prodigy 60 points

@Eyup: I am planning to work with the oxygen sensor and I am looking for some answers. Can you please tell me why you choose the 47Ohm load resistance? And also we can choose up to 100Ohm resistance so what is the effect on the startup timing of the sensor if we would increase the value of the resistance?

circuitos impresos

0 Eyup Semsi Yilmaz over 12 years ago in reply to dave johnson1

Prodigy 100 points

Hello!

If i am not mistaken,you already read datasheet. It has written 10Ohm to 100Ohm you can use.I have tested 10,47 and 100 Ohms. If you use;

100Ohm,the start up time will increase and sensor will be so sensitive.

10Ohm,the startup time decrease,but sensor won't be sensitive.

So 47 Ohm is middle of these values. And sensor life time decrasing according to resistor's value.

I hope i could help:)

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LMP91000 circuit design?