give external supply to nrf51

[nordicbeginner]

hello there,

i am giving external supply to nrf51. my external supply is usb 3.3 v. but when i connect it with nordic and then if i check it on multimeter , it shows me 2.12 v. can you tell me why??

[Sigurd]

What is the supply voltage to the LM1117? 3.3 V ? or 5 V?