RAK 4630 Power Rail Design

LPWAN Modules / EVBs
1

I’m designing a circuit for a RAK 4630.

From reading other posts, it appears to optimally power the module it is best to supply +3.3VDC and +3.6VDC.

I’m wondering if anyone would know the max power consumption of the rails (full transmit, Bluetooth and LoRa, and processing on the nRF52), so I can pick appropriately sized inductors for max efficiency.

2

Take a look in the one of base boards documentation: RAK19007

Regards,

Cláudio

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3

This isn’t what I’m after sadly; I’m well versed in the core setup.

4

There is no definite value for the max current.
It depends on too many factors, like

  • BLE TX power
  • LoRa TX power
  • LoRaWAN region
  • LoRa packet size
  • LoRaWAN data rate
  • other modules attached to the system
  • and mostly about your application being low power optimized or running useless in the loop() waiting for something to happen
5

That’s fair. Do you know if it’s an equal split across 3.3v and 3.6v? The 3.3v would be for the SX1262 and the 3.6v is for the nRF?

6

It depends how you connect the different supply pins.
On the WisBlock RAK4631 it is like shown in the schematics

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The SX1262 is supplied by 3.3V and the nRF52 is supplied by 3.6V-4.2V from the battery

7

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I’ll be setting it up like this.

8

That should be ok. If you have space, I would add some surge protection on the USB+/USB- lines

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9

Yup!
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