NRF51822: Terrible range with DCDC enabled

[rbolijn]

Hi all,

Hope someone can help me. We are using the NRF51822 on MDBT40-256V3 module. The IC used is revision V3. We're not using Bluetooth but our own proprietary protocol.

Everything works ok, except for DCDC. We’re using 3,6V battery for VDD. We have a pcb circuit with DCDC reference design (some extra L and C). DCDC seems to work fine since we checked AVDD:

-AVDD ~ 1,25V (floating) when DCDC is enabled and off (in between radio events)

-AVDD = 1,88V during radio events

-AVDD = 3,6V when DCDC is turned disabled.

This corresponds to the this thread: nRF51822QFAAH0: AVdd change

However, the receive range is very very small with DCDC enabled: only a few meters. With DCDC disabled it’s far more than 20 meters. Transmit seems to work just fine (havent checked exact range in respect to DCDC disabled).

Do you have any ideas what might be the problem?

[Kenneth]

There were a change in how to use the DCDC between rev2 and rev3 of the nRF51-series: infocenter.nordicsemi.com/.../pcn_092_v1.2.pdf

On rev3 you only enable the DCDC by writing to DCDCEN register in POWER peripheral during init, and then the DCDC will be automatically used by the radio. No need to disable or enable like on previous revision. Are you sure you are using it this way?

We might help you by taking a look at the schematic and layout, but then we should do this through MyPage on www.nordicsemi.com.

[rbolijn]

Yes we are using the DCDC by only writing the DCDCEN register during initialization. I will also upload the layout in MyPage