The incomparable ladyada tells us:
The next version of the Mintyboost is done and documented. This time it’s based on the LT1302 chip instead of the MAX756, which can provide up to 600mA (although I’ve found that with 2xAA’s it doesn’t really go past 450mA). The layout was also improved for better efficiency. The upgrade was necessary as the latest Apple products really need a lot of current to charge and hopefully they will work better now!
2 thoughts on “Mintyboost v2.0 is out”
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Ok, the caps she used were Xicon 10V 220uF electrolytic (I think PN: 140-XRL10V220-RC).
These appear to have an ESR of ~1ohm at 120Hz. Not sure what it would be at 200kHz, maybe half an ohm or so?
Anyway, the datasheet recommends the output capacitor ESR to be below 0.06 ohm with this design (see pages 7+8). Meeting that would most require a good tantalum or ceramic, which would increase the cost by quite a bit over the xicons.