1.TI datasheet for TPS61180/1/2 SLVS801B-DECEMBER 2007-REVISED MARCH 2009
does not provide recommendations for R2 value selection. In some schematics pages it is 51 Ohms 5% part, in some - 1%.
2. What efficiency I should expect for operations with Vbat=6V +/-5%, 60 mA load current(3 strands 20 mA each) and L1=8.8 uH (Rdc=200 mOhm)?
I achieved currently 85% at Vbat=6 V. Is there room to improve or it is good enough?