I'm searching for a boost converter to convert up small voltage (min 0.5V / max 81mA) to 5V. (the smaller the better)
Can you recommend a special type number?
The nearest I can find is this device: -
With a 0.5V input it will produce 5V but only with probably 50mA output (Green graph for TPS61202): -
Hopefully it'll work for your application
Do you want a particular chip that you use to build a circuit, or do you want a ready-built circuit? Pololu has a ready-build boost converter based on the NCP1402. The NCP1402 is a fine boost controller for low voltage/current, and the Pololu implementation is decent. http://www.pololu.com/catalog/product/798/pictures
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