Comment by torginus
15 hours ago
It also stood out to me how little stuff is in there - there's the uC itself, 3 transistors for heating the flavor canisters, an op-amp for the microphones, but other than that I don't really see anything - no external oscillator, no vrm (though a charger/BMS circuit must be in there somewhere).
I see lots more cost-cutting corners they could take...
Vapes are probably made in enough quantity to warrant custom silicon. Then the mosfets and charge circuit could be on the same die. It could be mounted COB (black blob).
They could probably use a single 'microphone' (pressure sensor) and determine which setting based on a photodiode.
The PCB's could be replaced with a flex PCB which integrates the heating elements (Vegetable Glycerine boils at 290C, whereas Polyimide can do 400C for a short while). Construction of the whole device can then involve putting the PCB inside the injection moulding machine for the cavities, eliminating all assembly steps, joints and potential leaks, and reducing part count
> Vapes are probably made in enough quantity to warrant custom silicon
Not when the MCUs might cost a penny and the other parts aren’t much more.
Putting high power electronics and analog into the same custom silicon as a custom digital logic is nontrivial. They’re made on different processes.
But you need very very little digital logic... The same kind of quantity to do the little power indicator LED's on a battery bank (which are charlieplexed btw), and thats done in the same ASIC that also has the 5V boost power supply (multi-amp gnd isolated n type mosfet) and charge circuitry involving voltage references and laser tuned comparators, and sometimes negotiates USB-C PD as well (needs an internal ROM). And the whole thing needs to be really cheap and with a standby current of uA's.
As long as you aren't interested in multi-Mhz operation, combining the rest at very low cost isn't too tricky.
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I love the term “high power” even though we are talking maybe a watt or two when that bad boy’s element is doing its thing!
I mean relatively it absolutely is high power. The quiescent current on that thing has to be microamps…
It’s just funny because to me “high power” is hundreds or thousands of watts. Like an incandescent light bulb or a hair dryer. Or at least it was until I started tinkering with battery powered microcontrollers and doing math to realize exactly how long an 18650 might power a small strip of individually addressable LED’s…
“High power” is a very relative term :-)
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The vape is disposable, no need for a charging circuit and maybe a simple ADC to determine battery life based on a discharge curve.
Apparently there is a charging circuit, because the battery will run out long before the fluid does
This is the brand I usually use. https://www.off-stamp.com
It has a separate magnetically attached battery / charging unit. I have to charge 5-6 times per "tank" that's attached. The battery side also has a mini-led display showing animations and battery / juice left so it's actually communicating with the tank side. A kit with battery and tank runs me about $25, but the tank alone is about $20. So they add $5 to cover the battery / charging component. It's a vice, but at least with this brand I'm not throwing away batteries weekly.
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