We are currently testing a first design iteration of a battery management and gas gauge PCB having implemented the BQ76930 analog front end combined with the BQ78350-R1 host controller. We are testing and verifying various functionalities one by one, and have now run into a problem. Using the EV2400 we are able to configure it using bqstudio 1.3.45.
We are trying to get the LED display functionality to work. From what I can tell, one press of the DISP button (or sending a DISPLAY_PRESS signal from bqstudio) should be sufficient for all the LEDs to light up when the Mfg Status Init[LED_EN] bit is set to 1, and certainly if RelativeStateOfCharge() returns 0x64 (LED Configuration [LEDMODE] is 0). This is the case (screenshot below).
However, there is no visible (or measurable!) activity at any of the LED# pins. In our particular design, we are controlling the LEDs by driving a small FET to switch on the LEDs (to alleviate the LED# pins from having to drive the LEDs themselves - is this strictly necessary though?)
We proceeded to physically remove the pull-down resistor and the FET in this case, leaving the pin completely isolated. Using a multi-meter we observed that the voltage on the isolated pin remained 0 V during a button press.
The schematic for how we connected the DISP button to the BQ78350-R1 (which I believe is correct?) is shown in the screenshot below:
*GND is connected to VSS
For good measure, here is a screenshot of the LED Support settings:
I've been doing a good amount of checking the Technical Reference, the Datasheet and the settings in BQstudio to see if there's something I've been missing all this time. I have not been able to find it.
Any help or suggestions as to how to proceed or things I've overlooked are greatly appreciated!
