We are trying to power source the mangoh red through an external regulator via the battery connector.
Yes, we know it is going beyond “regulations” but this is our requirement.
The regulator provides 5V ±4% with a maximum continuous current of 2.5A (more than a USB port) connected to the battery connector. The input goes up to 25V (this is our application requirement). Charging is obviously disabled. Power on the sierra module is reported to be 4.9V by the processor itself.
The board boots and software can be executed properly.
However, the radio module won’t come online. We have tried various combinations with the cm radio command, but no error is reported. It simply does not come up. If we go back to usb power then the radio works again.
In the design, BQ24296RGER is in charge of generating a single 3V7 signal that it is later separated to power the VBATT_BB and VBATT_RF signals, and we cannot identify any other dependency.
Note that BQ24296RGER is rated to support a VBAT input of 6.2V.
Thanks a lot.