Hey all, I’m working on a circuit that uses the L76K GNSS module (specifically the L76KB-A58 module). In my project, I don’t want to use a backup battery. So, I’d like to know if it’s necessary to connect the V_BCKP pin to the VCC pin, or if I can leave it floating.
I’ve already read all the documentation, but I couldn’t find an asnwer.
Thanks for your help.
I’m not affiliated with Quectel, so take my answer with a grain of salt; but I found a copy of the L76K hardware guide on WaveShare’s site [1] and my reading is that the VCC power supply will power the RTC domain and that there isn’t anything in the rest of the docs saying that V_BCKP has to be powered. I bet you’d be fine leaving it floating.
1.) https://files.waveshare.com/upload/d/db/Quectel_L76K_Hardware_Design_V1.0.pdf
Thanks for your time, WiFiLuke. Yeah, I read the document too and came to the same conclusion. However, since nothing’s stated explicitly, I figured I’d ask.
Hi Gcaricatech,
Please refer to power-up sequence below.
It’s necessary to connect to V_BCKP on L76K. If you don’t want to use a backup mode, you can connect VCC and VBCKP power circuit together. So that VCC and VBCKP can be powered at the same time, which meets the power-up sequence requirement.
Please note that: L76K is a ROM based module. If VBCKP is cut off, all the configurations you send to L76K will lose, and you need to send them again after power up.
Best regards.
What happens if I leave the V_BCKP pin floating? Unfortunately, my circuit is already in production! If it’s necessary to connect the V_BCKP pin to VCC when not using the backup mode, then you should clearly specify this in the datasheet!!!