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Tiny logic-controlled high-voltage buffers?

We often have something like a 5V or 3.3V logic line coming from an FPGA or microcontroller that needs to drive something like a 28V bias line to an RF PIN diode or some RF amplifier's power supply or what-not... and in generally we do this with a couple of FETs and a resistors or two, and it works fine. But it would be great if someone made a level-translator IC that had, say, somewhere between 1-4 "data" lines at TTL/CMOS logic levels that were translated over to high-voltage levels (say, 12V-28V) in a nice little SOT23-6 or uMax-10 or SO-8 package or similar. The output current would seldom if ever need to be >100mA, and in most cases it's

Reply to
Joel Koltner
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Can you use a regular push-pull comparator or opamp rated for 32V or more?

Cheap, and some are available as SOT23-5.

--
Regards, Joerg

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Joerg

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Not really tiny (SO14) but you can twist those "neg supply" telco drivers like TI's DS3680... (I once needed to drive GND referred relay coils for ultra low noise coupling)

Or maybe LM324?

-- Thanks, Fred.

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Fred_Bartoli

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That is for I

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Fred_Bartoli

Hmm... and run, e.g., Vcc/2 (where Vcc=5V or 3.3V or whatever) around for the negative input? Interesting idea... I'll go take a look at a few of them -- thanks.

---Joel

Reply to
Joel Koltner

ADG3123 ?

-Lasse

Reply to
langwadt

Yes, and best to provide some hysteresis. But keep in mind that unlike a logic FET pair they do not always pull all the way up to VDD.

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Regards, Joerg

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Joerg

ULN2803 in a SOIC package?

Good Luck! Rich

Reply to
Rich Grise

high-side H-bridge drivers?

Reply to
DJ Delorie

Those are open collector, they can only pull down but not up.

--
Regards, Joerg

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Joerg

Nice, very nice... thanks!

Reply to
Joel Koltner

LM5112 is a very cool part.

For lower-level stuff, just use an opamp and let it rail. Test it first and make sure it behaves... some don't.

John

Reply to
John Larkin

Depending on the load you want to drive you might try the On-Semi NUD31XX series inductive load drivers - where XX=05, 12, 24 and 60 specifies the maximum output/protection voltage. See

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These are actually low threshold (2.0V max) FETs with input and output protection. Can sink 150mA at Vgs 3Volt. Singles in SOT23-3, duals in SC74-6 package. Available form Mouser at 50c - 70c each, 30c - 35c for 100s.

Regards

Gerhard van den Berg CSIR

Reply to
Gerhard

Would a "digital transistor" do the job? They are prebiased transistors in a package that can drive a good amount of current.

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There are many types.

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a7yvm109gf5d1

Thanks John, it looks good.

Reply to
Joel Koltner

Occasionally. Usually the problem is sourcing 12-28V, but sometimes an open collector/drain is good enough, and those built-in resistors are nice.

Reply to
Joel Koltner

SOT23-6

But not for 28V stuff, there it'll go phssst ... *POP*

I toyed with it also but found it was to wimpy in one direction (IIRC pull-up) so my staple became the MIC4422. Costs maybe 10-20% more but it pulls in both directions with mucho gusto and isn't a white-knuckle ride on a non-regulated 12V supply because its rated higher in supply voltage. Also comes in inverted if you want to build a cheapo switcher.

That's what I'd try as well. It doesn't get much cheaper than that.

--
Regards, Joerg

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Joerg

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