Discussions

Dialogue:

Switch all ultrafit connectors to microfit.
Could you recheck the resistor values for a 95% precharge - or was that not the number we are going for?
Check precharge resistors for a fast precharge time.
The precharge is controlled through the precharge_sw load switch, from the PA9_Precharge_EN pin on the controller board as well.
Why hold Reset of the SR Latch LOW for 8.4ms?
Why is R50 1/4W?
Why 2.2uF 100V capacitors?
The paralleled precharge FETs should have resistors on their gates individually, not paralleled. This can cause oscillations, but is usually not an issue unless switching them on/off rapidly in a motor controller of similar.
Why is R17 a 1% resistor when the others in those voltage dividers are 0.1%?
I believe our DC-DC converter is set to 13.5V. Is there another isolated DC-DC converter that has a higher voltage rating? The XPPower one says 13.2V max. This is probably not a huge issue though.Currently, any thermistor overtemp will turn off the precharge and notify the controller board (but will not activate the discharge) This can be left up to firmware. We need to decide what to do if the discharge is overheating - ideas? Do we leave the high voltage on the motor controller, or do we keep discharge active and hope it does not burn?

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The 95% precharge should work out. It's unchanged from last rev, but I'll check it when I get back. (This is about the voltage dividers going to the comparator right?)
The holding reset on the SR latch I believe is to reset the SR condition since each time the board is turned on since it's in a race condition. Taiping did mention I could replace it with 2 FETs or something but I'll have to look into it.
R50 was 1/4W bc i was just looking for resistor values to fit the divider. I don't think the power should matter. I believe the same is true for R17 as well.
For the rest, those were unchanged from the previous rev but I'll take a look.We can leave the thermistor overtemp up to firmware but just not populating the opto-isolator that sends that signal to the precharge FETs. The MCU should be getting signals when a comparator senses overtemping.For the discharge overheat, i believe the problem was that the discharge FET got wet, so hopefully that doesnt happen again. If it overheats normally, we can't really just stop discharge by turning on the board but leaving the isolated side off so it doesn't go into precharge.