Hi all

I'm trying to operate simple solenoid valve using Camozzi U72 solenoid

www.camozzi.com.cn/download/product/ENG_2_2_35.pdf

It operates in 12V (5W) and has 3 inputs

And I'm using DRV102t solenoid driver

http://focus.ti.com/general/docs/lit/getliterature.tsp?genericPartNumber=drv102&fileType=pdf

DRV102 output pin 6 shows nice PWM output variating from 0 to 12V, but actual solenoid load pin never goes below 6,8V. So the PWM output variates between 6,8 to 12V in load output

why the PWM load never goes 0V ? I guess that my diode selection could be wrong

Or is it possible that DRV102 could not driver Camozzi U72 ? (I doubt)
Thanks in advanced.

 

The 1N4008 diode is a rectifier diode, thus it is not designed for high switching frequencies. Replace it with a schottky diode to reduce the forward voltage drop too.

 

I Replaced IN4008 with IN5822, but still the load PWM variates from 6 - 12V...

Is the schottky IN5822 correct choice to drop forward voltage ?

I'm using another IN5822 fron output to load as well

 

Still I can't get my solenoid to work properly....

The PWM in load connect, as well as in DRV102 pin 6, is variating between 6-12V.

What should I do to make the PWM variating 0-12V and to get the solenoid working ?

Should I add some pull down resistors ?

 

Hello,

What is your intention with the solenoid?
As far as I can see the solenoid is only for open and close purposes.

Greetings,
Bertus

 

The solenoid data is a little confusing...12Vdc solenoid, 4W.= 0.333 amperes; @ 5W, I = 0.416 amperes. Minimum impulse is 18 mSec., so you will need a high current driver transistor, 1/2 amp. (min). The fact that the output never goes below 6 volts is a question mark? Is that zener diode clamping the output voltage level to 6 V? Just use a standard
Silicon free wheeling diode across the coil, 1N4001. A N-Mosfet should work here, or a darlington NPN.

Cheers, DPW [ Everything has limitatons...and I hate limitations.]

 

Solenoid should control air pressure to user selected rate. Pressure control should be quite linear. And that's why PWM controlled solenoid is needed. There will be D/A controlled PWM duty, but at this moment I just try to get the correct PWM load voltage levels to solenoid.

Without solenoid, the PWM output is perfect, but when solenoid is connected, the level changes to 6-12V and solenoid won't work

DRV102T application notes only gives a hint for series diode and flyback diode connections, but .. ... it just won't work

The schematic should follow the DRV102t application circuit and I added two schottky diodes to protect over voltages.

Any ideas ?

 

Could I connect one of the following diodes (i'm out of 1N4001 today):

1N4148
1N4007
1N5408
1N5822

 

Look at the min. interval required to energize the solenoid; 18 msec. does the PWM output have this capability? Any impulse shorter than this will do nothing.

Cheers, DPW [ Follow the money]

 

DRV102 has 24kHz internal PWM, so it seems that the impluse (on-off-on) period is too short for that solenoide.

But it is interesting that this chip is dedicated to drive solenoids.

I tested the circuit without PWM output, just setting 0 to input pin of DRV102 and solenoid load pin stays in 12V. So the same problem with this chip still exists.

Do you have any other solutions to drive that solenoide wih 3.3V logic ?

Maybe IRF540 to control solenoide and some bipolar to control IRF540 and taking care that 3,3V logic ?

Could you list all components which are needed to drive 3,3V solenoid circuit ?

It would be a great to have a list before going shopping. Thanks a lot

 

Hello,

In my opinion the DRV102 is for proportional valves.
You could make your own PWM with a much lower frequency (say 1 Hz).
This would let the valve "rattle" at a much lower speed and have an out put proportional to the percentage of the PWM.

Greetings,
Bertus

 

Maybe you are right that DRV102 is for proportional valve control.

This chip seems to be a very rarely used and I just heard that this could be a good chip for my application.

What could be the best solution to drive such a solenoid application ?

Any reference circuit diagrams ?

 

Hello,

Take a look at this thread:
http://forum.allaboutcircuits.com/showthread.php?t=33302

There Bill Marsden is explaning the PWM and how to make it.

Greetings,
Bertus

 

Thanks guys,

Just need a quick review of my MOSFET solenoid driver before going component shopping

Is this okay ? Or do I need some more protection like caps and diodes ?

The idea is that MOSFET is controlled by bipolar, which reverse the logic

 

Hello,

I would make the following changes, see picture:

Driving the input and mosfet a little harder.

Greetings,
Bertus

 

Thanks a lot.

Would you also give a short explanation changes you made ?