My customer has an Intrinsically Safe design (must protect all charge storage components - like capacitors - from excessive current flow).
2 Questions related to this:
1) Customer has a 470ohm series resistor on the REGIN node, but this seems to cause problems with the bq34z100 fuel gauge. The gauge seems to not want to start-up properly. (seems to power cycle). Why? Is there a maximum series impedance allowed on the REGIN pin? The customer's application requires a series impedance to 'protect' the input capacitor.
2) There is a concern that a fault current from GND can back-drive through the SDA & SCL output pins (though the Open Drain output FET body diodes) back to the host processor. The EVM also has the D1 diode - which would conduct in a similar manner... Any suggestions on protecting the SDA & SCL nodes? one partial answer would include e knowing the maximum series impedance we can put on the I2C lines - and perhaps remove D2 (on the EVM). Adding a series FET-clamp might be another possible option
Third question: Can the bq34z100 read-back state of charge during a charging cycle? i.e. if the pack is being charged - can we use the bq34z100 to monitor the level of charge while it is charging - for an added level of safety. And perhaps stop the charging process if the pack is near or exceeding what is determined to be a full charge level. We are looking at both Li+ and NiMH cells.
Thanks!
