Hello I am currently working on upgrading my company's solenoid driver board. A 5/2 solenoid requires inverted 24v signals. So 24v on one side, and 0v on other will deactuate the valve, and other way around will actuate it. The current system is a bit complicated imo. A digital signal from the mcu goes through an isolator, then is split through a hex inverter, and then a ULN2003 to take the voltage to 24v. Is there any simpler way?

 

You didn't specify the current.
I use Allegro A4953 for a similar application.
Toshiba do an equivalent TB67H450 which is easier to get.

 

For driving solenoids, I have used Solid State Relays. This one has the isolation inside. 60V 1A.
You will need to add a diode. 1N4002 Look at the ULN2003, there is a diode from output to +24V. That is important.
Is the 24V ac or dc? This relay does not care. There are AC only relays that are lower cost.

 

Post your complete circuit.

Are you are driving the solenoid with a bridge configuration to get the reverse polarity?

 

Considering the use of the ULU2003, the voltage must be DC and likely there is no bridge configuration.

is split through a hex inverter

The word split puzzles me.
I agree, with more information, we can only guess.

 

Surely the solenoid valve is not driven directly by a ULN2003?

 

This is the rough diagram. @ronsimpson What I meant by split is that the trace is split and one goes through the inverter and the other doesn't so we get (24V and 0V) or (0V and 24V) on Input1 and Input2. But now that I think about it, maybe an isolated relay would suffice better? Just switch which side the 24v goes to and have a break on the other side. @Ian0 The current as far as I know is minimal, 0.35 watts at 24v, so 14mA? I'm very confused by the old design myself. The voltage is all DC @ronsimpson .

 

Are there three wires on the Solenoid? +supply, On, Off ???
The ULN2003 only pulls down. It cannot pull up. Just saying.

 

This is how the solenoid valve wires look (just for reference). Its used to control air flow, Powering either side(24VDC) powers the solenoid on that side and moves it, changing air path. I'm currently looking into whether the other side not being connected has any effect or not

 

I'm currently looking into whether the other side not being connected has any effect or not

Your solenoid valve looks like a bistable type with two solenoid coils. Surely both sides have to be connected, albeit powered alternately?
Is 0.35W the standby power (i.e. after a solenoid has pulled in) or the peak power (i.e. while the solenoid is pulling in)?

 

Would an L298 H-bridge work for this situation?
This is a dual bi-directional driver. You can use it for both coils on the solenoid and it has the inverter function built-in.

 

This is how the solenoid valve wires look (just for reference). Its used to control air flow, Powering either side(24VDC) powers the solenoid on that side and moves it, changing air path. I'm currently looking into whether the other side not being connected has any effect or not

Why not simply wire the two coils in parallel, in anti-phase? Then you need only one H-bridge.

Or is it possible that you need to drive each solenoid with a DC unipolar signal to activate?
Post the part number of the solenoid.

 

. @Ian0 The current as far as I know is minimal, 0.35 watts at 24v, so 14mA? I'm very confused by the old design myself. The voltage is all DC @ronsimpson .

In that case the A4953 would be perfect. Maybe even overkill.

 

@Alec_t There isn't a distinction for starting and holding for the standard variant, but either way, we can expect a max of 0.45W. So 18.75mA.

Also, I just checked, powering only one side works fine. I see no visible difference in operation.

@MrChips the part number is sy5220-5lz-01. Yes I think it isnt bipolar so the anti phase method wouldn't work

@Ian0 @MrChips yes I think either would be overkill. I'm looking for something simpler with a smaller footprint. Also sorry but I forgot to mention we are going to design 1 PCB for 8 such valves each. And there have been some incidences of the valves malfunctioning and wires shorting so we were also looking at isolation between the mcu and valves, is that ideal?

 

Would an L298 H-bridge work for this situation?
This is a dual bi-directional driver. You can use it for both coils on the solenoid and it has the inverter function built-in.

View attachment 290754

Yes. The A4953 is more modern and needs fewer external components.

 

Also, I just checked, powering only one side works fine. I see no visible difference in operation.

also in this scenario wouldn't it be better to use an isolated SSR instead of an H bridge?

 

also in this scenario wouldn't it be better to use an isolated SSR instead of an H bridge?

If it works on a single coil why would they supply it with two coils?

 

That looks like a 2 Solenoid "MAC-Valve",
this FET-Driver should do a fine job ................
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also in this scenario wouldn't it be better to use an isolated SSR instead of an H bridge?

Not unless the 24V supply is completely separate from the logic supply.

 

If it works on a single coil why would they supply it with two coils?

i meant that you can power one coil at once and the other doesn't have to be connected.