More anon mayhaps, but you can get about as close to zero as you'd want by
running a boost winding for an ancillary supply for the IC.
Alsop, note that cap energy is largely exhausted at near zero volts as
energy capacity is proportional to V^2..

For say 8V max, energy % at 1V is (1/8)^2 ~=3D 1.6%.
At 2V you have (2/8)^2 =3D 6.25%
And at 1.8V (1.8/8)^2 =3D~ 5.1%.

Getting the last few % is "nice" but odds are you will gain more by
attention to design - lower track losses, good connections, capacitor
quality ... .


      Russell
--=20
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