Hello,
I have a new design utilizing the BQ20Z655-R1 Gas Gauge and I am having an odd issue. There are two seemingly separate issues. The first revision of the layout has been completed and I just got prototype boards in house to do some testing. I have found these two issues so far.
First, the LCD will turn off for about 1 second as soon as I begin to discharge the battery pack. The discharge will not be interrupted, and the LCD display will light back up after a second. The LCD panel also lights back up just as if it was never off. Its definitely not a complete chip reset as I would assume the display to blink one lcd block for about 5 seconds, then go to the current soc, in this case 3 blocks (50%).
Second, the LCD will blink off for about 0.250 seconds while just sitting there. I have a board sitting on my desk now just to observe while doing other work and every now and then I can catch it out of the corner of my eye blink just once real quick. Much quicker than the other error described above. This leads me to ask, how often does the chip do a function like reading voltages or something that would drastically increase the current consumption on a periodic basis?
I have a sneaking suspicion that it may have to do with a weak ground to pins 7,22,31,34. I would like to know what the absolute limits of supply voltage to the silicon are to cause the lcd driver portion of the circuit to drop out for a period. or maybe is it the 3.3 regulator being overwhelmed? I am using 100k pull up resistors on each of the five segments on the lcd. I saw later that it was recommended to be 330k in the datasheet.
just timed the interval of the blink while idle. I got 100 seconds. Sleep current time and sleep votlage time are both set to 60 seconds.
Thanks for all help.
JD