DCDC Startup Time

RE: DCDC Startup Time

Einar Thorsrud — Wed, 11 Nov 2015 11:56:38 GMT

That is good to hear. If you are satisfied with the answer I would appreciate it if you could accept it by clicking on the check mark to the left oft he answer.

RE: DCDC Startup Time

Ken N — Wed, 11 Nov 2015 11:47:35 GMT

Thanks Einar, totally clear now.

RE: DCDC Startup Time

Einar Thorsrud — Wed, 11 Nov 2015 11:34:16 GMT

Most of the thread you link to is related to earlier revisions. The DC/DC will not consume power when the radio is not active on 3rd revision chips. This could perhaps have been stated more clearly in the Reference Manual, but is covered in Section 12.1.3.

RE: DCDC Startup Time

Ken N — Wed, 11 Nov 2015 11:19:45 GMT

Thanks for the response Einar.

In fact that is how we are currently using the DCDC. However in this article, one of your colleagues mentions the DCDC consuming 300uA when enabled, admittedly for Rev 2 hardware. So if this is no longer the case with rev 3, and once enabled the DCDC is only active when the radio is operating, then is it correct that the DCDC uses no current other than when the radio is active?

If that is the case then presumably any DCDC startup time is absorbed into the startup time of the radio.

Thanks

RE: DCDC Startup Time

Einar Thorsrud — Wed, 11 Nov 2015 10:05:21 GMT

I do not have the number up front, but the startup time depend (significantly) on the current consumption. However, it may not be necessary to know, as the management of the DC/DC was changed in revision 3. In that revision you only have to enable the DC/DC once, and it is automatically used when the radio is active and disabled at all other times. Thus, assuming you use the SoftDevice, you only have to make a call to sd_power_dcdc_mode_set() at startup, and you can forget about it.

The behavior of the DC/DC in revision 3 chips is documented in Section 12.1.3 of the reference manual.

You can compare the current consumption when using the radio for DC/DC disabled (Section 8.5.2) and enabled (Section 8.5.3) in the product specification.

RE: DCDC Startup Time

Ken N — Wed, 11 Nov 2015 09:03:03 GMT

We're using the nRF51822, rev 3

RE: DCDC Startup Time

Einar Thorsrud — Wed, 11 Nov 2015 09:00:10 GMT

Is this question about the nRF51 or the nRF52?