Just curious: Why Vcc max is spec'd at 3.9? ... well ... not 4.2? ;)

[FI]

Hello,

It just a diode drop away from 3.9 to 4.2, and 20% typical of a Lipo discharge, just wondering whether the IC design and process is really that tight. The nRF52 runs on a wide dc Vcc range, I especially like the low voltage side, this shows the sensitive blocks are designed to account for dc supply variations. On the high side, popular Lipo cell has an initial discharge voltage of 4.2 (Out of spec), and spend most of its useful life in the 3.7 range (Within spec) and done at ~3V, over a period of mAhr on Iave. So typically, no boost supply is needed. I am just wondering whether the nRF52 is designed to be able to work with a Lipo directly without any LDO.

Discussions are welcome. I don't see much of an advantage using LDO (best few ohms) from Lipo battery vs a Lipo directly (1 ohm), in the sense of either efficiency or dropout (without using any boost buck or charge pumps).

Cheers

FI

[Stian Røed Hafskjold]

Well, 3.9V is not really within spec. 3.6V is the max recommended operating voltage: infocenter.nordicsemi.com/.../recommended_op_conditions.html

3.9V is from the absolute maximum before you brick the chip: infocenter.nordicsemi.com/.../abs_max_ratings.html

Maximum ratings are the extreme limits to which the chip can be exposed for a limited amount of time without permanently damaging it. Exposure to absolute maximum ratings for prolonged periods of time may affect the reliability of the device.

[FI]

Thanks for the clarification. Regards