LDO regulated to 1%?

[David]

I am using the nRF51822 utilizing the internal LDO setup. I received a question during regulatory submittal that I am not able to answer and am looking for help on. Is the voltage supplying the radio ciruit regulated to 1%?

Thanks.

[FormerMember]

The LDO can only power the nRF51822, and it is not possible to draw any excessive current from it. Could you check if you need to have the accuracy of an LDO that is integrated in the chip and with no real access to it?

[David]

The question is posed to guide the procedure of testing for the Japan radio mark. If the voltage powering the radio is regulated to 1% then we won't have to test the max and min variations of the supply voltage. Am I wrong in assuming that the internal LDO is powering the radio circuit? If the internal LDO does not power the radio circuit or is not confirmed to be regulated to 1% then I will have to essentially perform the same test procedure 3 times using the max voltage, min voltage, and nominal which roughly equates to 3.5, 3.2, and 3.3v input to the nRF51822. If the LDO does power the entirety of the radio circuit and is regulated to 1% then I will only have to apply 3.3v and test once.

[FormerMember]

The accuracy of the internal LDO is 1.5 % plus load regulation and offset. However, it should work fine to qualify for TELEC (Japan radio mark). I would recommend you to contact our regional sales manager for Japan and ask him how it works. I will send you a PM with his contact details.

When you find out what you had to do, it would be nice if you could update this tread with the steps/clarification :)