An incredibly small 5V switching regulator module!

Specifications:

• Board size: 0.40"x0.35"

• Input: 6-20V (3-4S LiPo)

• Output: 5V @ up to 1A

• Efficiency: 85.35% @ 1A (measured)

Components:

• U1: LM53601LQDSXTQ1

• L1: DFE252012F-4R7M=P2

• C6, C7: GRM21BR71A106KA73L

• C3: 885012205067

• C2: GRM155R70J105KA12J

• C8: GRM31CR71E106KA12L

• C1, C4: GRM155R71H104KE14D

Cost:

• Boards: $0.70 for 3 at OshPark

• Components: $6.66 at Mouser plus S/H (that’s a bit ominous…)

• Total cost: $7.36 for 1 module

• Assuming you can solder it all yourself…

Not the cheapest, but probably the smallest!