Hello,
I'm trying to find a low power voltage reference/regulator, I need 12V capa ble of delivering 1.5mA to a load, my input voltage range is from around 65 V to 100V. I was looking at a TLVH431, but according to the datasheet it n eeds around a minimum of 1mA cathode current to regulate, since my input ra nge 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?
much thanks!
pable 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 inpu t 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?something like these:
-Lasse
1: That's a current-limit diode, not a regulator.
B: it still dissipates power while regulating (or limiting) current.
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
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
12.7V, then use a high-gain NPN transistor with a VCE a good margin better than 100V as an emitter follower.-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
e ,
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
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?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.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
I've seen schematics similar to this, with claims that they work:
+100V o---------o---------. | | .-. | | | | | | | '-' | | | | | | |/ o-------| | |> | | | | | o---------o your favorite voltage | | | .-. | | | | | | | '-' .-------. | | | | | LM385 |-----o | | | '-------' | | .-. | | | | | | | '-' | | === === GND GND (created by AACircuit v1.28.6 beta 04/19/05But 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.
-- My liberal friends think I'm a conservative kook. My conservative friends think I'm a liberal kook. Why am I not happy that they have found common ground? Tim Wescott, Communications, Control, Circuits & Software http://www.wescottdesign.com
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?Put a burden resistor on the reg?
Jamie
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?Jamie
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?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
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?Yikes, that's just what I need for the gadget I'm working on, to get
12 volts from 24...50. I was going to use an LM317HV, but this is a lot smaller.-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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?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:
-- JF
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?This is cute:
Being LTC, it's of course insanely expensive.
-- John Larkin Highland Technology Inc www.highlandtechnology.com jlarkin at highlandtechnology dot com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom timing and laser controllers Photonics and fiberoptic TTL data links VME analog, thermocouple, LVDT, synchro, tachometer Multichannel arbitrary waveform generators
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
300 Hz continuously, which at 120V p-p and 1.4 uF is a lot of peak current (160 mA), i.e. 19 watts peak if I use class AB drive.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
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
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?
1.4 MICROfarads is a heap of piezo.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.
-- John Larkin Highland Technology, Inc jlarkin at highlandtechnology dot com http://www.highlandtechnology.com Precision electronic instrumentation Picosecond-resolution Digital Delay and Pulse generators Custom laser drivers and controllers Photonics and fiberoptic TTL data links VME thermocouple, LVDT, synchro acquisition and simulation
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
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
2V capable of delivering 1.5mA to a load, my input voltage range is from ar ound 65V to 100V. I was looking at a TLVH431, but according to the datas heet 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 u p to its max. Anyone know of a better solution for this?
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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
-- Dr Philip C D Hobbs Principal Consultant ElectroOptical Innovations LLC Optics, Electro-optics, Photonics, Analog Electronics 160 North State Road #203 Briarcliff Manor NY 10510 USA +1 845 480 2058 hobbs at electrooptical dot net http://electrooptical.net
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