Pressure control solenoid

[PICer]

I need to control a pressure control solenoid, basically the solenoid is controlled by using current. The current needs to be between 0 - 1.1 amps @ 4-5V (need the ability to control the current via a microcontroller in small current steps). Was thinking of using a PIC but don't know how to design the circuit? Assume use an analog output of a microcontroller to controll a transistor but it would need some kind of current sensing ability? Can anyone help or point me in the right direction? Thanks.

 

[Russlk]

Since the solonoid is a linear resistance, unless you are varying the voltage very fast, it is only necessary to control the applied voltage. This circuit, using the OPA544T fro Burr-Brown will drive the solonoid.

 

[PICer]

I was only going by what the info on the solenoid said, it didn't mention being controlled by voltage, said must the controlled by current. It's used for fluid control and 0 amp is 0% duty and 1.1amps is 60% duty cycle. So are you saying i can just use voltage to control it? I was thinking maybe using PWM would be a good alternative? I've never controlled current from a microproccessor before, Thanks for the reply.

 

[PICer]

How about the drv101 from TI, that seems to do what i need??
**broken link removed**
Think this will work??

 

[Nigel Goodwin]

I was only going by what the info on the solenoid said, it didn't mention being controlled by voltage, said must the controlled by current. It's used for fluid control and 0 amp is 0% duty and 1.1amps is 60% duty cycle. So are you saying i can just use voltage to control it? I was thinking maybe using PWM would be a good alternative? I've never controlled current from a microproccessor before, Thanks for the reply.

If you're planning using a PIC, pick one with hardware PWM (the 16F628 would be good, and easy to program as it's EEPROM based). PWM would be a lot more efficient, easier and cheaper to do. Using analogue voltage control wouldn't be a very practical way of doing it, more complicated, more expensive, and much more inefficient - but would give you heatsinks to warm your toes on :lol:

 

[PICer]

Do you have any example schematics?

I found this, seems like it would do what i need??

 

[Nigel Goodwin]

I don't know what U1 in the diagram is, but you would need a driver transistor to feed your solenoid, you couldn't feed it directly from a chip (unless it had a suitable driver built in).

 

[PICer]

It's supposed to be able to handle 2 amps which is 1 more than i need. (U1 is labled DRV101)

 

[Nigel Goodwin]

It's supposed to be able to handle 2 amps which is 1 more than i need. (U1 is labled DRV101)

I've never heard of it, but a quick google looks like it's made for the job!.

 

[PICer]

That's what i'm thinking so i ordered one, we'll see. Thanks