Power supply solution for nRF51822

[Jerome Bioret]

Hello all,

In many thread I can read that it is not recommended to use the internal DC-DC converter to supply the nRF51822. Can you tell me why it is better to use an external DC-DC with the internal LDO ?

It's important to know that because it makes a significant change on the BOM cost.

Thanks, Jerome

[syntroniks]

devzone.nordicsemi.com/.../ are the recommendations by nordic on the dc-dc converter. I'm just posting this here for my own reference.

[syntroniks]

It all seems to come down to efficiency. The DC-DC converter becomes an attractive option when current draw is relatively high (read: radio on, ~15-20mA). The LDO on the other hand, wins out in low draw situations (read: most of the time).

If you are drawing enough current to make a DC-DC more efficient than the LDO I would operate the device off of 1.8 volts - otherwise we just use the internal LDO and no switching converters.

[Jay Tyzzer]

As a follow up. The main reason for the DC/DC not being used on the nRF51x22 series is that the startup time when using the BTLE stack was taking a bit to long which negated the current consumption saved by using it. This was only on the REV 1 and REV 2 parts.

In the most recently released version, Revision 3, the DC/DC converter block has been optimized and is fully functional for all protocol stacks available for the devices.