humm, I was gonna do the design myself without the BOSCH IC, I was looking around for vendors of the BOSCH IC and never found any.
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humm, I was gonna do the design myself without the BOSCH IC, I was looking around for vendors of the BOSCH IC and never found any.
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Europe
http://www.semiconductors.bosch.de/e...tributoren.asp
http://www.rutronik.com/english/index.html
http://www.rutronik.com/produktderwo...kw09/index.php
The CJ110 and CJ120 are on this list:
http://www.rutronik.com/download.php...osch-Flyer.pdf
USA
http://www.bosch.us/content/language1/html/1284.htm
Robert Bosch Corp.
38000 Hills Tech Drive
Farmington Hills, MI 48331
By telephone: 248-553-9000
By fax: 248-553-1426
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TY for the info.
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Hi,
Print the page 3 and 4 of the CJ120 PDF.
(The Block diagram page and the Application circuit page).
http://www.semiconductors.bosch.de/p...y_extended.pdf
Add to the application circuit the two op-amp's and connect them
as they are depicted on the block diagram page.
(Draw that with a pencil inside the CJ120 on page 4).
The two op-amp's:
Pumpstrom-Regler = Pump current control
Pumpstrom-Meßverstärker = Pump current sense amplifier
Voltages:
==============================================
PIN Vcc = +5 V
==============================================
PIN VM = +2.5 V (Virtual ground voltage source)
(0.5 x VCC)
==============================================
PIN US = +2.95 V (Nernst cell reference voltage source)
(450mV, reference to virtual ground)
===============================================
PIN GND = 0 V
================================================
The two op-amp's have a single polarity supply.
(+5 and GND).
On the output of the op-amp "Pump current control"
you will need a 100 ohm resistor.
* * *
The idea is to replicate what Bosch is doing inside the CJ120.
You will need a way to simulate the LSU4 during the testing of the circuit.
(DC +/- milliampere meter and a voltage that goes from 4.0V down to 2.5).
Do you understand how it works?
Luciano
Last edited by Luciano; - 25th May 2005 at 22:23.
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I have not seen the additions you have made on the PDF because the current computer I use gives an error with the file, I will look at it later on a nother computer.
I pretty much understand how the circuits works. I have made a citcuit long time ago that was very similar to what the Bosch ICs are doing. That was with analog circuits right now I am trying to do most of the Analog stuff using a MCU so to minimize tolerance problems and to cheapen things up and also to add dataloggin capabilities to it.
I built my first circuits based on the Bosch Datasheet for the Sensor itself because I never knew the Datasheets for the ICs existed publicly. The circuit I built before knowledge of the Cj120 datsheet was similar in many ways to the CJ120 but more simplier. Now that I seen the CJ120 the only thing I can not understand is on Page 3 or 4 of the CJ120 PDF, the use of Rical (82 ohms). The fact that I can not speak German only adds to the problem. But I am sure somewhere in my subconcious my mind is solving the issue, so it will only be a matter of time before I know what the RiCal does. I suspect it maybe a reference restance that the resistor in the pump Cell (Ri) should be at during normal operations. The reason I say this is becasue I know pretty sure that the Pump resistance should be close to 80 ohms during normal operation and not the 100 ohms that is shown on the diagram.
There is no need to simulate the BOSCH LSU sensor in my testing since I have about 4 of them lying around. Also the Pump current goes through an external 61.9 resistor, I suspect the 100 ohms you are talking bout is the internal resistance of the pump cell.
I would love to by the bosch ICs from rutronik but they require huge quantity purchases something in the thousands per order.
If I can digitize most of the analog circutry I can make a very cheap, fast and accurate Wideband reader.
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BTW Luciano TY very very much for posting up the documents, because of the new information I found in there I am going to make a few design adjustments to my circuits and MCU program.
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================================================== ======
My previous post:
The PDF was not modified. You will have to draw the two op-amp's
and their connections on page 4. The 100 ohm resistor on the output
of the op-amp "Pump current control" is present in the Tech Edge circuit.
================================================== ======
The CJ120 also measures the Nernst-cell internal resistance (Ri) which
is used to determine the temperature of the sensor. The internal resistance
of the Nernst-cell is 80 ohm when the sensor ceramic temperature is approx. 750°C.
By knowing the (Ri) you can control the heater supply voltage so that the
temperature of the sensor is kept at a nominal temperature of approx. 750°C
which is needed for *precise* measurements.
The Nernst-cell internal resistance is measured by pulsing the Nernst-cell via a
capacitor and a resistor.The pulsing must be done between 1kHz and 4kHz.(CJ120 3kHz).
On the Tech Edge Pty. Ltd. schematic you can see that they measure the Nernst-cell
internal resistance and also measure the effective heater voltage and current.
On the CJ120 block diagram you can see that the effective heater voltage and
current are not measured. The document http://wbo2.com/lsu/Y258K01005e03mar21eng.pdf
describes the maximum permissible heat up rate when the heater is switched on.
When you know the Nernst-cell internal resistance then you can control the heater
without measuring its voltage and current.
Luciano
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