Seems a pretty small niche....
There are many, ... a micropower comparator will probably be just fine and draw less than battery self-discharge.
For example
http://www.digikey.co.uk/product-detail/en/texas-instruments/TLV3691IDCKR/296-37910-1-ND/4900957
75nA current draw, 0.9v minimum supply.
If you don't need the threshold voltage as low as 0.6ish a MOSFET will give you near-zero input current.
If you need low threshold, a high-gain bipolar transistor will do that with pretty low input current. (anyone know what the limiting factor is here ? Noise ?)
So that leaves applications that absoutely need both low threshold voltage and low input current, and can't afford the drain of a comparator.
And where you're not worried about a single-source device from a non-mainstream supplier.
Seems a pretty small niche....
Personally i think Dave was a bit harsh.. But thats his call, his forum and Blog. Its his style and its the cynical engineer thing.. The irony is that without daves video i woudl have never known about this, and i now i do.
Our IR example would have required hundreds of photodiodes in parallel to turn these devices on.
Our ferroelectret and piezo sensor outputs would collapse to nothing if we used these devices. Once you are down to below square centimetres of active sensor material, it is easy to be in the GOhm output impedance range. If you stomped on the material, then you would overvoltage these commercial detectors.
The RF rectenna needs a very low threshold to get any range. That is why we made another version of this detector with a 0.46 V threshold. If you put your rectenna next to the transmitter, you'd over-voltage a commercial voltage detector. If you protect the input with a zener diode, then the leakage kills your range. We then found, that the 100pA input current of this lower threshold device, made the range worse, so we went back to using our 6pA input device with the slightly higher threshold.
What is "a bit harsh" anyway? Because I spoke my opinion? Because I spoke my opinion and I have a big audience?
Dave, you have a big diverse audience, and that is important, and hard to cater for.
As we have seen from the aggressive comments and under the busted video and our videos, some of your audience take your message as being "I hate the bullshit research that University X is conducting, which is just smoke and mirrors".
Some respected bloggers have suggested there are simple ways of doing what we do, which has been taken as proof that funding is being wasted.
Your viewers trust you, and to some, the good message is not coming through, and all our videos, even the RF one, were getting mostly dislikes and aggressive comments, as soon as your video went up.
I think your message is twofold:
(1) Good: "They have a good research outcome (the chip, not the TV), with good characteristics (datasheet) with no competition (yet) in niche areas (sensor-driven stuff)",
(2) Bad: "They have poor demos because the marketing has made the demo look like the target application (which it is not), and for this apparent application, they have neglected to describe the remaining power drains, by implying wrongly that the total system power was zero, when it was only that of the sensor that was addressed. Their product has narrower use than they are implying, and they need to find the right kind of demos."
So whilst I see that you are saying lots of nice things about our chip (thanks), as you start and end with (2), thousands of viewers don't appear to see (1).
Anyway, I'm taking this all as a good lesson in life, and hope we talk more about the science. No hard feelings.
OK, we know the following:
Microcontrollers listening to IR signals take microamps of power.
The SMPS in the TV is really inefficient, running at 10% or less.
A typical lithium battery will run a microcontroller for years, and it has the energy to start the SMPS.
So I think we know what to do. Just put a lithium primary battery into the TV and run the standby power from that.
Personally i think Dave was a bit harsh.. But thats his call, his forum and Blog.
Even if not immediately identifiable as having any commercial viability in itself, I look at it like research brainstorming - it could spark something brilliant. This could be some bizarre application that was not immediately apparent, or a stepping stone for someone to develop something else.I would be stunned if there is not some immediate niche application for this chip, because AFAIK there is not an equivalent "harness energy, trigger output" kind of chip?
Those who don't think there is an app probably just haven't thought hard enough or aren't involved in an area that needs it.
There will no doubt be some out there that see it and go "wow, that is just does what I need for my dooflewinkle project".
Anyway, I'm taking this all as a good lesson in life, and hope we talk more about the science. No hard feelings.
Come to think of it. This chip may be interesting for more complex (microcontroller) based circuits. In those you usually have to leave the microcontroller powered in order to wait for a wake-up event. This means there will be a regulator and other circuitry on all the time and currents quickly add up to the 100uA ball park even if you switch off power to parts of the circuit. A chip which can make do with the power coming from (for example) a piezo based push button could eliminate all the tedious (software) work of putting a microcontroller to sleep and use cheaper parts which don't need to be ultra low power.
Come to think of it. This chip may be interesting for more complex (microcontroller) based circuits. In those you usually have to leave the microcontroller powered in order to wait for a wake-up event. This means there will be a regulator and other circuitry on all the time and currents quickly add up to the 100uA ball park even if you switch off power to parts of the circuit. A chip which can make do with the power coming from (for example) a piezo based push button could eliminate all the tedious (software) work of putting a microcontroller to sleep and use cheaper parts which don't need to be ultra low power.You'd be doing a pretty poor job if it was taking that much. Any decent MCU with a low- power regulator can easily get well below 10uA in a sleep mode which can be woken periodically by watchdog, 32K crystal and external edge.
Come to think of it. This chip may be interesting for more complex (microcontroller) based circuits. In those you usually have to leave the microcontroller powered in order to wait for a wake-up event. This means there will be a regulator and other circuitry on all the time and currents quickly add up to the 100uA ball park even if you switch off power to parts of the circuit. A chip which can make do with the power coming from (for example) a piezo based push button could eliminate all the tedious (software) work of putting a microcontroller to sleep and use cheaper parts which don't need to be ultra low power.You'd be doing a pretty poor job if it was taking that much. Any decent MCU with a low- power regulator can easily get well below 10uA in a sleep mode which can be woken periodically by watchdog, 32K crystal and external edge.With a single MCU on a 3V coin cell you can easely reach sub uA currents but that is not always the case. In some circuits it is not just the MCU (which usually draws more than the datasheet promises because you have to leave more stuff on to make it all work) but also the regulator (think about using a battery >>5V) and other circuitry as well. In those cases it all adds up to a whole lot of (worst case) current.
With a single MCU on a 3V coin cell you can easely reach sub uA currents but that is not always the case. In some circuits it is not just the MCU (which usually draws more than the datasheet promises because you have to leave more stuff on to make it all work) but also the regulator (think about using a battery >>5V) and other circuitry as well. In those cases it all adds up to a whole lot of (worst case) current.
I wonder, how does it react when powering a device off? For example, suppose it is a device which saves log files to flash storage during the shutdown sequence (like with some entry level NAS devices, and routers), does the circuit wait for the load to drop below a certain threshold, or does it simple toggle on when one pulse is given, and then toggle off when another pulse is given?
With a single MCU on a 3V coin cell you can easely reach sub uA currents but that is not always the case. In some circuits it is not just the MCU (which usually draws more than the datasheet promises because you have to leave more stuff on to make it all work) but also the regulator (think about using a battery >>5V) and other circuitry as well. In those cases it all adds up to a whole lot of (worst case) current.
Along with shutting down external circuits when not in use, I will sometimes use this circuit to expand Vin range with a regulator such as this (20nA quiescent current) for very low power applications if a battery with a high voltage source is needed. Usually one would choose a battery whose nominal voltage is closer to your system's operating voltage and use a boost converter if a higher voltage is required as you can turn that off as well when not needed.
Did you check the datasheet on that 20nA regulator? It says typical and no maximum. Also the regulation is piss-poor. I wouldn't design this thing in IF I could look past the 'Microchip' brand.
While you're at it, discuss PCB manufacturing techniques to keep leakage from ruining your day, I'm sure you've encountered this in your research and know it'll stop customers dead in their tracks if they don't address it.
We might do a video on low power measurements, I think people might find that useful.
... I will sometimes use this circuit to expand Vin range ...