What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

RE: What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

toomanynumbers — Fri, 16 Aug 2024 16:10:50 GMT

Hi Bjorn,

Were you able to get an answer for Q1? I'm looking for the quiescent current and efficiency of REG0 DCDC under the conditions of 3.0v ≤ VDDH ≤ 4.2v, VDD=1.8v.

The reason for asking this is to evaluate the potential benefit of external regulation using the TI TPS62840.

If you cannot disclose specific values for the REG0 DCDC, could you confirm just with yes/no whether the TI or REG0 has the greater efficiency and lower quiescent current?

TI TPS62840:

60nA Iq

3.0v ≤ VIN ≤ 4.2v, VOUT=1.8v

Efficiency ≥80% @ 1μA, ≥88% @ 100μA, ≥90% @ 10mA

Thank you.

RE: What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

UBAN — Fri, 24 May 2019 05:12:17 GMT

Thank you for the information !

RE: What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

bjorn-spockeli — Tue, 21 May 2019 09:20:52 GMT

Hi Uba,

This is the reply i got from R&D:

Regout0 max setting is 3.3V. The spec is min 300mV dropout, limiting input voltage to max 3.6V for guaranteed operation. When input supply drops further below 200mV dropout, the nRF will still work, but IDLE or SYSOFF modes will have increased current consumption ~100uA.

If possible, would be better to use for example 3.0V setting for REG0 when used from Li-Ion

RE: What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

UBAN — Tue, 21 May 2019 03:47:00 GMT

Hi bjorn,

In Question 2, you said to confirm this with R&D.
Could you share the information ?

Best regards,
uba

RE: What's the LDO vs DCDC efficiency difference (Reg0) in NRF52840 Rev 1?

bjorn-spockeli — Tue, 15 May 2018 07:56:52 GMT

Hi Jishnu,

Q1: We do not have any public data on the quiescent current of the LDO or the DCDC of REG0 stage. I have raised this question internally and will come back to you on this.

Q2: I would expect that the VDD will follow VDDH, i.e. VDD = VDDH-0.3V, when VDDH drops below the output level set in the REGOUT0. However, I will have to confirm this internally with R&D. I have raised this question internally and will come back to you on this.

Q3: Yes, it is be possible to change the output of the REG0 LDO at run-time by modifying the REGOUT0 register in the UICR peripheral. However, this will require you to readout all the UICR registers, temporally store the content, modify the __ register value in the readout content, erase the UICR registers and then re-write the modified register values. Note: This option is only available if the access port protection(APPROTECT) feature is disabled. Erasing the UICR registers is not possible if APPROTECT is enabled

Q4: Yes, we have identified a possible solution for both Errata 197 and 202. There will be a product change notice(PCN) a minimum 90 days before any change can take place(has not been issued yet), so I don't expect any fix to be available before late this year. We need time to ensure that the fixes for these issues, does not have any negative impact on already existing designs.

Since we do not expect a fix to be available before late 2018 our current recommendation is to NOT use REG0( both LDO and DCDC) and instead add external regulator for voltages above 3.6V and tie VDDH to VDD on nRF52840.

Best regards

Bjørn