I know this question has been asked and answered, however, I am still having some trouble understanding how I should set up my power.
For my application, I am using an external watchdog IC (TLP5010) to “wake-up” my 3.3V regulator (TPS63051) which then would power on the RAK4630 chip. The EN pin of the regulator is tied to a three input OR-gate, one input from the pulse of the watchdog, one input from the RAK4630 itself so it can keep itself on longer than the pulse by using a GPIO pin, and a jumper which allows it to be tied to battery voltage to force it to stay on during programming and debugging.
The timer circuit works exactly as intended, however, I noticed that even in “timer” mode, the MCU stays on and functional when I expected it to be turned off. I tied VBUS to USB voltage (not plugged in during this test), VBAT_NRF to the battery votlage (14500 Li-Ion battery), and all other voltages to the regulated 3.3V from the regulator. As a test to make sure it was not firmware related, I uploaded Meshtastic, and that worked totally fine regardless of if the regulator power good pin was high or not.
I tested my regulator and although the EN pin was low and the PG pin was low, there was still 3.3V on the output. I am not 100% sure if it was drawing current from the supply or not, but
I wanted to double check and see if I misunderstood:
- Does the RAK4630 stay on and powered purely from the VBAT pin, or is my regulator just staying on and awake when it shouldn’t?
- If the answer to the first question is yes, is there a way I can prevent the RAK from being on and active at all until the 3.3V regulator is on and functional?
Thank you all for your time!