Lumileds Luxeon 3535L Lime
- Digikey 1416-1440-1-ND
- optimum efficiency from 1mA to 30mA (didn't measure higher current because of lack of heatsink).
- Best efficiency at 5mA. It's then 8% better than at 1mA or 30mA. This has been measured with a TSL2591 connected to a Protrinket 3V and the LED mounted about 10mm directly above it. A current source controls the LED current, while a DMM is used to measure the LED voltage. A more decent setup can be found here.