> Efficiency is important and I don't want to ruin it with a LDO vreg
> that draws 5-10 (!) mA by itself, as the load is at most only 20 mA

Microchip have plenty of low Iq LDO regulators

http://www.microchip.com/ParamChartSearch/chart.aspx?branchID=3D9004&mid=3D=
10&lang=3Den&pageId=3D79

I bought a bunch of these, MCP1801 3.3V, $0.42 / 1 - 25

30uA Iq at 20mA o/p, below 70uA at 150mA

http://www.microchipdirect.com/ProductSearch.aspx?keywords=3DMCP1801T-3302I=
/OT

http://ww1.microchip.com/downloads/en/DeviceDoc/22051D.pdf

Joe=20

--=20
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