25V H-bridge for <3V logic?

speed needed?

- Henry

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"Joerg" schrieb im Newsbeitrag news:UK9rh.60448$ snipped-for-privacy@newssvr13.news.prodigy.net... | Went through H-bridges up and down the block but so far no luck: Is | there a small and reasonably priced one that can swing 25V or more, not | much current (

Actually, none at all. If it needed a second to think about switching over that would be fine ;-)

Sorry Joerg. What is the meaning of your second sentence in german?

Why not use AVQ257 or such? An optocoupler MOSFET relais SMT.

Price is approx. $0.50 sum for 4 devices.

- Henry

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"Joerg" schrieb im Newsbeitrag news:m5arh.60458$ snipped-for-privacy@newssvr13.news.prodigy.net... | Henry Kiefer wrote: | | > speed needed? | >

| | Actually, none at all. If it needed a second to think about switching | over that would be fine ;-) | | -- | Regards, Joerg | |

Who makes it? I can't find it at the usual North American distributors. Not even at Newark which carries much of the Farnell line.

"Joerg" schrieb im Newsbeitrag news:PZarh.23732$ snipped-for-privacy@newssvr29.news.prodigy.net... | Henry Kiefer wrote: | | > Sorry Joerg. What is the meaning of your second sentence in german? | >

| > Why not use AVQ257 or such? An optocoupler MOSFET relais SMT. | >

| > Price is approx. $0.50 sum for 4 devices. | >

| | Who makes it? I can't find it at the usual North American distributors. | Not even at Newark which carries much of the Farnell line.

On my harddisk ;-)

Maybe you find it somewhere on the japanese website.

The MOSFET gate is active driven low if the LED current falls below the threshold. I think they mentioned it in an app note somewhere but not in the datasheet.

- Henry

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Dual opamp?

John

news:PZarh.23732$ snipped-for-privacy@newssvr29.news.prodigy.net...

threshold. I think they mentioned it in an app note

Ah, NAIS. Thanks. Unfortunately they are a bit largish, would take up almost the space of a discrete solution.

Possibly but their behavior can become really bizarre when VCC falls below the drive level. I've seen some latch up, others had their "logic" inverted and only returned to normal after everything was removed. The voltage actually goes to zero and back up in this application.

"Joerg" schrieb im Newsbeitrag news:Hubrh.16733$ snipped-for-privacy@newssvr19.news.prodigy.com... | Ah, NAIS. Thanks. Unfortunately they are a bit largish, would take up | almost the space of a discrete solution.

Maybe simple 4x optocoupler SMT if the load is not inductive?

- Henry

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news:Hubrh.16733$ snipped-for-privacy@newssvr19.news.prodigy.com...

Thanks for the hint, I have to check what's available in a small package. To be honest I hadn't even thought about optos before because I only remember them as large. The load is almost purely resistive, maybe some C but never inductive. But I must provide ESD protection.

"Joerg" schrieb im Newsbeitrag news:7Sbrh.23744$ snipped-for-privacy@newssvr29.news.prodigy.net... | Henry Kiefer wrote: | | > "Joerg" schrieb im Newsbeitrag news:Hubrh.16733$ snipped-for-privacy@newssvr19.news.prodigy.com... | > | Ah, NAIS. Thanks. Unfortunately they are a bit largish, would take up | > | almost the space of a discrete solution. | >

| > Maybe simple 4x optocoupler SMT if the load is not inductive? | >

| | Thanks for the hint, I have to check what's available in a small | package. To be honest I hadn't even thought about optos before because I | only remember them as large. The load is almost purely resistive, maybe | some C but never inductive. But I must provide ESD protection.

Try SFHxxx, 615 or such, I lost my memory.

A harddisk motor driver should work. Sorry, no type number here.

- Henry

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news:7Sbrh.23744$ snipped-for-privacy@newssvr29.news.prodigy.net...

news:Hubrh.16733$ snipped-for-privacy@newssvr19.news.prodigy.com...

Ploughing through the Vishay site right now. Digikey seems to be down, probably on account of the Siberian climate over there.

Most of those need a fixed supply voltage which I won't have. I need to phase-cycle a variable voltage.

Can you divide the drive logic swing down to, say, 100 mV? That would surely be safe.

John

Sure. I am all for unorthodox uses of standard parts but I haven't done that to an opamp yet. VEE would be on ground, VCC on a variable drive that goes between zero and 20V. Then the amps would bang to opposite sides on each zero transition.

It would almost have to be an RR type or at least an amp type that doesn't remain more than 0.5V off either rail when saturated (a few mA). And it would have to come on gracefully with rising VCC, not too snappy. Does any cheap one come to mind? Would have to be 10uA Iq or so because I must also measure load energy but it can be slow. The old 324 can't really do all that.

"Joerg" schrieb im Newsbeitrag news:Qcdrh.10456$ snipped-for-privacy@newssvr12.news.prodigy.net...

Some EL driver devices have a internal thyristor or even full-bridged MOSFET driver stage. This stage is driven by a simple boost converter. If you can control the oscillator of such a beast it will do what you want. I've seen a chip having two different osc for the stages to control.

Cheap, low-voltage input, very small. Check the output current capability.

- Henry

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news:Qcdrh.10456$ snipped-for-privacy@newssvr12.news.prodigy.net...

driver stage. This stage is driven by a simple boost

I've seen a chip having two different osc for the stages

That's the caveat, usually you select them by lamp frequency range and then the frequency is fixed (and really high, a few hundred Hz):

"Joerg" schrieb im Newsbeitrag news:rrerh.10471$ snipped-for-privacy@newssvr12.news.prodigy.net... | Henry Kiefer wrote: | | > "Joerg" schrieb im Newsbeitrag news:Qcdrh.10456$ snipped-for-privacy@newssvr12.news.prodigy.net... | >

| > Some EL driver devices have a internal thyristor or even full-bridged MOSFET driver stage. This stage is driven by a simple boost | > converter. | > If you can control the oscillator of such a beast it will do what you want. I've seen a chip having two different osc for the stages | > to control. | >

| | That's the caveat, usually you select them by lamp frequency range and | then the frequency is fixed (and really high, a few hundred Hz): |

Why not use a complimentary MOSFET pair two times? 2x SO-8 or even smaller. Even digikey should have such.

If you can go toward 15V there is the old ICL7667. Maybe a second source is higher rated.

I seek one if you pay me :-)

- Henry

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Check:

Good night (here)!

- Henry

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"Joerg" schrieb im Newsbeitrag news:rrerh.10471$ snipped-for-privacy@newssvr12.news.prodigy.net... | Henry Kiefer wrote: | | > "Joerg" schrieb im Newsbeitrag news:Qcdrh.10456$ snipped-for-privacy@newssvr12.news.prodigy.net... | >

| > Some EL driver devices have a internal thyristor or even full-bridged MOSFET driver stage. This stage is driven by a simple boost | > converter. | > If you can control the oscillator of such a beast it will do what you want. I've seen a chip having two different osc for the stages | > to control. | >

| | That's the caveat, usually you select them by lamp frequency range and | then the frequency is fixed (and really high, a few hundred Hz): |

| | -- | Regards, Joerg | |

Another one:

- Henry

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"Joerg" schrieb im Newsbeitrag news:rrerh.10471$ snipped-for-privacy@newssvr12.news.prodigy.net... | Henry Kiefer wrote: | | > "Joerg" schrieb im Newsbeitrag news:Qcdrh.10456$ snipped-for-privacy@newssvr12.news.prodigy.net... | >

| > Some EL driver devices have a internal thyristor or even full-bridged MOSFET driver stage. This stage is driven by a simple boost | > converter. | > If you can control the oscillator of such a beast it will do what you want. I've seen a chip having two different osc for the stages | > to control. | >

| | That's the caveat, usually you select them by lamp frequency range and | then the frequency is fixed (and really high, a few hundred Hz): |

| | -- | Regards, Joerg | |