Switch mode DC/DC regulator IC and system design

[bhargav6]

Hello all,

I am currently working on a project where, I have to measure the voltage and current at the load connected to (ECU) Electronic control unit in a truck.

The battery Voltage Vin (12V- 48V) has to be varied . The input from the battery will be given to Switch mode DC\DC regulator IC (which I have to choose, whose input and output voltage range is well within the range of 4V-50V. And it can measure the current or has current limit upto 12A. I have looked for many IC from TI and also from Ltspice (found a few for e.g Ltspice 8390).

The question is I too wish to use micro-controller to control the output voltage.

I am bit confused, as too what IC with sub components I use to design my project.

 

[kubeek]

Your best option would be a step-down converter, with the feedback going throug an opamp which will be used to alter the voltage coming from the feedback divider and adjust it so that you get the voltage you want.

 

[ronsimpson]

The battery Voltage Vin (12V- 48V) has to be varied . The input from the battery will be given to Switch mode DC\DC regulator IC (which I have to choose, whose input and output voltage range is well within the range of 4V-50V.

Vin = 12-48V
Vout = 4-50V ???? Set by computer. Measured by computer.
I out = 12A current limit Measured by computer???
Will the Vout be greater than the input voltage?

 

[bhargav6]

Vout will not be greater than input voltage .(it will be controllable.

Iout - current sensing circuit .. preferably I looked for Ltspice 8390 which has input output cureent sensing monitor pins (this will be measured ,current sensor and then to the controller)

The loads connected to the ECU (electronic control unit) which will draw current upto 20A.

 

[bhargav6]

I have been searching for a while now for buck converters which will have such operating ranges and can deliver utpo 20A of current. I found a few from ltspice and texas instruments, but I am not sure which IC I must use.

You said about the feedback from the step-down converter, going to the op-amp. I have to look for few ICs more I guess

 

[ronsimpson]

truck.

The battery Voltage Vin (12V- 48V)

Truck = automotive
I have designed many products for automotive.
Car= 14.5V running and 12V not running. (design for 9V to 30V) The reason for 30V is because there are large spikes.
Truck= some are "24V" so 24 to 29V.
Some times the battery is installed backwards.
Some times voltage regulator is not good and the voltage is too high.
Some times the battery is "open" or removed and the voltage is too high.
Question: Why "12V- 48V" Are you saying 1-battery, 2-batteries, 3-batteries, or 4-batteries? OR "12 and 24V system" So the battery could be as low as 9 or 10V and as high as 30V and the "48V" is for a short time spike?
-----edited-------
Will you make millions of these or is this very small volume?
Is price very important?
If you only are going to make three then the design time is much more than the parts cost BUT if you make millions then the parts cost is the most important.

 

[ci139]

spend a few extra tens of dollars on your converter and few extra hundreds on professional installation - to be able to go to sleep at night with the knowing that by the night it hasn't burned down
or simply consult your insurance company first

 

[ronsimpson]

**broken link removed**
I did a project with"bricks" like this.
This one:Vin 9V to 40V 30A (output set by "trim" which a computer adjusts)
There are smaller ones 20A.
The price is high but they did not have to pay me to design it. So I got nothing. LOL

 

[bhargav6]

Actuallly , As per your question

The Vin - (Vbattery) will be single , but the input voltage will vary from 12V - 48 V (nominal )

The ECU (Electronic control unit ) which will have connected loads will draw current upto 20A depending.. (ours is eTCV ECU ) which will valves and all connected etc

Here I need to also measure the current (meaning in my circuit will also sense and measure current, limit it)

In your above comment do you mean "trim" it can control the output voltage, (by computer)

Can I use a micro-controller to control the switching power supply (program it with req switching freq and so on ) ?

I shall look for the pdf you have provided, and get back

I am making this design or a board (as a PLug-In module) which in future can be used for some other application ,cost does not matter.

Thanks

 

[ronsimpson]

In your above comment do you mean "trim" it can control the output voltage, (by computer)

"trim" controls the voltage. Either by a resistor or a voltage. Many little computers can make a 0-5 Voltage.
On another post I showed a 25A current IC used to allow a computer to measure current.

 

[dr pepper]

4v to 50v, sounds like a Ficm, or injector controller maybe?

The injector power supply in most european cars actually have 4 supplies, one 48v supply per injector, the Lm2577 is a popular chip, on eof these can only provide about 1a at 48v from a single 12 batt.

You need something more along the lines of a system that uses a smps Ic with a outboard switching device, maybe something like a Uc3842 controler chip & associated parts, such a project is reasonably complex and would be in the realms of a more seasoned hobbyist or pro.

You could try ebay, you can get step up supplies from china, current ratings are a bit optimistic, derating by 3 would be a good start.