controller Charge Pump?

[Ron Marcus]

I need more info. Why a charge pump? What is your initial voltage? What is your needed voltage? I have run a 5 volt LCD screen from a 3 volt PIC using the PWM output. There are app notes for pushing out over 200 volts using a step up coil and diodes from a lowly PIC!

I like coils for step up, but the EMI can be a problem. What is the application?

Ron

[toalan]

the application is a bit odd. it is to control an oxygen sensor is a car, basically i need to source enough charge such that the catylitic reaction in the oxygen sensor is at steady state.

The amount of charge i need to pump in to reach that steady state is proportional to the amount of oxygen left over from internal combustion. it is this amount of oxygen that i am intersted in measureing. Most designs use voltage source pushing current through a small resistor to supply the current needed, and then use A/D to find to voltage drop across the resistor to find the steady state current.

But I would like to do away with using A/Ds, if i had a way to use PWM to control a charge pump or current source that would make things alot simplier.

I need something that I can control percisely to do the following:

supply: -4ma to +4ma
the voltage range of operation would be between -5V to 5V.

I am a bit stuck in finding something, I can explain things in more detail if needed but basically I need a PWM controlled current source/charge pump, even a voltage controlled current source/chrage pump is okay, My only requirement is that the resolution and percision need to be high and it should not be very complex.

Regards

Alan To

[Luciano]

What about using a standard zirconium lambda sensor?

Sensor output ranges from 0.2 Volts (lean) to 0.8 Volts (rich).
A perfectly balanced or "stoichiometric" fuel mixture of 14.7 parts
of air to 1 part of fuel gives an average reading of around 0.45 Volts.

Luciano

[toalan]

I am wokring with a wideband sensor and not the narrow band sensors.

[Luciano]

See this link:
http://wbo2.com/2a0/schem.htm

[toalan]

that is the techedge one, I am not looking to "bite" his design. His design is overly complicated in my opinion.

[Luciano]

Hi,

Feel free to "bite" the BOSCH design.
(See the block diagram of the IC CJ110).

But, doesn't it look familiar somehow?

Luciano

* * *

CJ110 - Lambda Probe Sensing IC for LSU4.
http://www.semiconductors.bosch.de/p...y_extended.pdf


CJ120 - Lambda Probe Sensing IC for LSU4.x
Ri Measurement; SPI-Interface; Diagnostics
http://www.semiconductors.bosch.de/p...y_extended.pdf


Source:
http://www.semiconductors.bosch.de/e...ine/engine.asp

* * *
Bosch LSU 4.2 Planar Wide Band Lambda Sensor:
http://wbo2.com/lsu/Y258K01005e03mar21eng.pdf

* * *

[eoasap]

I need more info. Why a charge pump? What is your initial voltage? What is your needed voltage? I have run a 5 volt LCD screen from a 3 volt PIC using the PWM output. There are app notes for pushing out over 200 volts using a step up coil and diodes from a lowly PIC!

I like coils for step up, but the EMI can be a problem. What is the application?

Ron

Ron, how do you run a 5V LCD from a 3V PIC using PWM ? i'd love to try it out.

[Luciano]

April 02, 2007

Hi,

I have completely abandoned this project.
Please do not send me private messages about this thread.

Best regards,

Luciano