low power voltage reference recommendation

pable of delivering 1.5mA to a load, my input voltage range is from around

something like these:

-Lasse

B: it still dissipates power while regulating (or limiting) current.

A quick visit to DigiKey's voltage reference page finds slews of shunt references with currents much lower than that.

But you want a regulator, not a reference.

What are you really trying to do? Regulators that are ultra-low current and that withstand 100V are thin on the ground -- you may have to roll your own. Helping us with details like whether that 1.5mA is going to be continuous or intermittent, how tightly regulated the 12V needs to be, and what your component budget is would be helpful.

For a small-run jobbie that doesn't need great regulation I'd see if I could find a really low-current adjustable shunt reference, set it to

is?

the idea was to use the cld instead of a resistor to feed the shunt reference keeping the current at a (constant) minimum

it is hard to get around dissipating power...

-Lasse

of delivering 1.5mA to a load, my input voltage range is from around 65V to

You can make your own regulator from a zener and an emitter follower.

Depletion mosfets are fun too. Something like one of these circuits,

with an LND250 (marginal on current) or a DN2530.

I've seen schematics similar to this, with claims that they work:

But I haven't analyzed it, tried it, simulated it, worked around a circuit that used it, or otherwise had any mileage with it. Whether it works or bursts into strong oscillation is highly dependent on the way that the LM385 compensates its loop, and somewhat dependent on your load

-- so no promises.

of delivering 1.5mA to a load, my input voltage range is from around 65V to

Put a burden resistor on the reg?

Jamie

of delivering 1.5mA to a load, my input voltage range is from around 65V to

Jamie

of delivering 1.5mA to a load, my input voltage range is from around 65V to

Maybe something like this?

The fixed output version is 10V out, the adjustable will go to 12V.

Lots of margin for spikes on the input (rated for 450V).

--sp

of delivering 1.5mA to a load, my input voltage range is from around 65V to

Yikes, that's just what I need for the gadget I'm working on, to get

apable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V.  I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my inp ut range is a bit wide that's going to go up as my input voltage goes up to its max.  Anyone know of a better solution for this?

Nice part! The schematic looks a bit like JL's shunt regulator.

Say John, for your third schematic (the shunt regulator) should you take the output from the 'upstream' side of the current limiting resistor?

George H.

capable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V.  I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my input range is a bit wide that's going to go up as my input voltage goes up to its max.  Anyone know of a better solution for this?

No, that would break both the current limiting and the regulation.

of delivering 1.5mA to a load, my input voltage range is from around 65V to

Try this:

. Vin . | . [Rs] . | . +---------+-----+ . | | | . | [R1] | . | | | .[LM4041-N ADJ]-+ [Rl] . | | | . | [R2] | . | | | . +---------+-----+- . | . GND

Here's the data sheet so you can figure out the values of the resistors:

of delivering 1.5mA to a load, my input voltage range is from around 65V to

This is cute:

Being LTC, it's of course insanely expensive.

capable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V. I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my input range is a bit wide that's going to go up as my input voltage goes up to its max. Anyone know of a better solution for this?

Only about four bucks, it looks like, for a one-chip solution.

Coincidentally I am just this minute running a simulation of a couple of these driving a piezo stack. A customer of mine needs to run a piezo at

A synchronous buck running off a 150V rail might save me 90% of the power dissipation by pushing current back into the input supply, which would sure be nice. Even a $25 BOM would be about 2% or less of the price of an OEM solution.

Unfortunately the LTC3639 doesn't seem to run backwards at all, at least not according to LTspice, which AIUI is pretty reliable with LTC switcher chips. Bummer.

Cheers

Phil Hobbs

capable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V. I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my input range is a bit wide that's going to go up as my input voltage goes up to its max. Anyone know of a better solution for this?

I don't suppose you can resonate it. Big inductor anyhow.

A uP based synchronous buck approximates an infinitly-variable gear set, the holy grail of automotive design. Takes NRE but would be dirt cheap in production.

Hmmm, does an inductor in series with a piezo make a linear driver amp more efficient? Might.

capable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V. I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my input range is a bit wide that's going to go up as my input voltage goes up to its max. Anyone know of a better solution for this?

Especially if it resonates. Unfortunately resonating 1.4 uF at 300 Hz takes almost 200 mH, and since piezos get unhappy if you run them backwards for long, I'd need a HV power supply anyway. Plus the customer wouldn't like the inflexibility and temperature drift of something with a Q >= 10.

The piezo has to move a macroscopic object by ~10 um p-p at 300 Hz. That's whomping pretty hard--this thing will be _loud_ when it's running. The piezo I'm looking at is the Thor Labs one with the integrated strain gauge,

It's a relatively low volume, high value application, so it won't support a whole lot of engineering effort. I might just do a brute force duty cycle integrator for this application--as the Victorians used to say, "Add mass 'til nothing breaks".

Cheers

Phil Hobbs

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That looks like a NEC Tokin piezo stack. When you get around to ordering production quanties we get a similar one from Bravo Electro Components

at about 1/3 of what thor labs charges.

George H.

capable of delivering 1.5mA to a load, my input voltage range is from around 65V to 100V. I was looking at a TLVH431, but according to the datasheet it needs around a minimum of 1mA cathode current to regulate, since my input range is a bit wide that's going to go up as my input voltage goes up to its max. Anyone know of a better solution for this?

gauge,

Thanks, George, good info. Attaching the strain gauge might be more than the customer wants to do, but who knows?

Cheers

Phil Hobbs