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Dual H-Bridge driver for latching solenoids

Hello,

I'm designing a board which will contain a block for driving latching solenoids (H-Bridge needed).

The first solenoid acts as a lock (activated at the start of the machine and deactivated at its stop) and the second one, as a security valve.

These solenoids are activated with a single pulse (pulse width > ms). They drive 2A.

I started by designing my own H-Bridge with MOSFETs and optocouplers but it took too much footprint on the board (compared to the use frequency of the circuit).

I plan to use A3995 Motor driver from Allegro and MC33926 from Freescale as a fallback solution in case of component obsolescence. They have very low footprint.

Do you know other solutions (maybe better) to do this straightforward application?

Thank you, Johann

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Reply to
johsey
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Who told you you need an H-bridge for simple bang-bang on-off latching solenoid control?

The instructor?

Thanks, Rich

Reply to
Rich Grise

AFAIK latching solenoids need a reverse current pulse to disengage.

Reply to
Dennis

OK. The only latching solenoids I've seen had two actual solenoids; one to set, and the other to reset.

So what's the real problem? johsey has already picked a couple of H-bridge chips - just pick one that meets the needs, send the appropriate pulses, and you're done.

If board footprint is restrictive, I'll have to defer to the layout experts, like John or Jim.

Have Fun! Rich

Reply to
Rich Grise

Neat, I haven't seen those.

Yeap.

Reply to
Dennis

@ Rich: Dennis has already answered your question. Each solenoid have a single coil and needs a reverse current to be unlatched, thus the need for an H-Bridge.

I posted this thread to have feedback from people who would have some suggestions for other ICs (some I would have missed or I am not aware of) that can fit my requirements or other "off-chip" solutions.

The footprint is not too restrictive but it is very annoying to have components for a "low frequency use" that take a big footprint.

Thanks, Johann

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Reply to
johsey

il

any old bipolar stepper driver should ahve what you need, you might get away with L293 it is rated for 2A peak, else L298

-Lasse

Reply to
langwadt

y

If you had AC available, you could just gate one half-cycle with a triac. Positive half-cycle latches it, negative unlatches it; do both at power-on to reset the thing to a known state.

If you could trust a capacitor, you could capacitor-couple to the coil and use a high-side and low-side switch transistor.

And if you don't mind a pulse transformer solution, a center-tapped primary would also let you do both pulse polarities, with two switch transistors. Two amps for a few milliseconds is easy for a transformer. If the solenoids were available with two windings, no transformer is needed, of course.

Paying for an IC with two power NPN and two power PNP is the hard way to do it, according to my wallet.

Reply to
whit3rd

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