And Electrodragon also offers a Mini Boost Buck DC Board 1.8-5V to 3.3V, for Battery Juice R2:
Use full battery juice!
• Super mini size 11.5×9.5mm, SOT23-6 IC with only three caps
• Input Voltag 1.8-5V, output 3.3V up to 150mA
• Constant Frequency Operation at All Loads. Low Noise Constant Frequency (1.2MHz)
• Automatic Soft-Start Reduces Inrush Current
• Shutdown Current <1 uA, No load current is 1.77mA.
• Short-Circuit Protection
• No Inductors
• Standard 2.54 pin output, 3.3V-GND-VIN (face to top), can be used as a normal SMD part.
Testing for reference:
• 1.8V VIN -> 3.3V output
• 1.5V VIN -> 3.1xV output, still can drive a lot MCUs.
Updated to R2: