nRF51822: Connecting VCC and AVDD?

RE: nRF51822: Connecting VCC and AVDD?

Håkon Alseth — Fri, 28 Mar 2014 09:32:51 GMT

Hi Kartik,

We recommend that you connect AVDD and VDD together when running on internal LDO, as shown in the reference circuitry. It is correct that it's an internal connection, but to lower the resistance between the two nets, we recommend that you connect them externally when running on LDO power scheme.

Best regards Håkon

RE: nRF51822: Connecting VCC and AVDD?

Kartik Lamba — Fri, 28 Mar 2014 00:43:38 GMT

Hi Håkon,

A quick follow-up question: If I am not using the DC/DC converter, would SB1 on the PCA10001 schematic need to be bridged? Or is there an internal LDO which powers AVDD from VDD?

Thanks, Kartik

RE: nRF51822: Connecting VCC and AVDD?

Oleh — Mon, 27 Jan 2014 12:20:02 GMT

Hi Håkon, it is good to hearing from you again.

the reason for this question is: I've got few PCBs with DCDC configuration, but the solderbridge was defauls connected. Next PCBs are with int-LDO and low-energy configuration, so do not have this problem.

But still wanted to ask if there was any damage caused to the chip in the case of DCDC... now I know :) I shouldnt try it :))

Thank you also for explanation!

With best regards Oleh

RE: nRF51822: Connecting VCC and AVDD?

Håkon Alseth — Mon, 27 Jan 2014 09:47:25 GMT

Hi again Oleh,

By connecting VDD and AVDD together while in DCDC operation, you will bypass the DCDC in effect and may damage the chip. This will not work (double checked with HW-designer).

What you should do is use the reference design w/DCDC (figure 16 in the PS v2.0). This will also work with LDO operation, as there is an internal switch from VCC_NRF to AVDD. The chip will start up on normal LDO until you enable the DCDC in your firmware.

If you are to connected VCC_NRF and AVDD, you just remove the components on "DCC" pin (ie: run nRF on normal LDO operation power scheme).

Best regards Håkon

RE: nRF51822: Connecting VCC and AVDD?

Oleh — Thu, 23 Jan 2014 22:58:08 GMT

Håkon, thank you for the explanation.

Following question: for the DCDC operation, connecting VDD and AVDD will damage the chip? or will the chip power up/start?

Thank you Oleh

RE: nRF51822: Connecting VCC and AVDD?

Håkon Alseth — Tue, 26 Nov 2013 12:42:51 GMT

Hi,

For LDO operation: There's an internal coupling between VDD and AVDD, so that solder bridge does need to be shorted. However, the internal switch will add a series-resistance, so shorting SB1 it will lead to a lower resistance.

For DCDC operation: Then there should not be a wired connection between AVDD and VDD, as AVDD will have another level than VDD.

Best regards Håkon