This would make more sense with a schematic, but here is a summary of some findings. i used the same convention for terminal numbering of CN201 as is used up in CN101, i.e. pin 1 is in the bottom right corner and pin 8 in the top left corner looking into the PCB connector.
So CN201 Pin 1 is the white wire, which is the "DCSW" from the EV-ECU found in the FSM. i traced this to the Soft Start pin 8 of the PWM controller chip IC201. i'm guessing this discrete provides the start command for the DCDC.
Pin 3 is the red wire, +12V Hot all the time. This is routed to the emitter of Q212 on the bottom layer of the board. More work is needed to ring it out.
Pin 5 is the black wire, chassis ground.
Pin 6 is the yellow wire, +12V switched by ignition. This line is clamped by a zener marked "30" ZD202 to ground, then it passes to the emitter of Q210 marked "S6". The collector goes to a 1k resistor R232 and then on to Pin 7, which is the brown wire and signal "SDW" of the FSM. The base of Q210 is pulled low thru the collector of Q209 "L6", the base of Q209 is controlled by the OR result of pins 1and 2 to IC206. There is a multitude of op amps, OR, AND logic, plus op amps, but i couldn't get thru it all.
Pin 7: The EV-ECU can sense the status of the DCDC with this signal, if it goes Hi to 12V then the DCDC is working okay; if not then something is faulty and it's time to shut down.
There is no microcontroller and no CAN buss. It is all analog circuits on a multi-layer circuit board (the +5V and chassis ground appear to be carried on internal planes).
The TR105 is a stepdown where the HV is pulsed thru the primary and two LV supplies are created in the secondaries. One secondary is used for the supplies on the HV side of the isolation gap in the PCB, e.g. for IC101 which controls the switching of Q110 to pulse the primary. The other secondary is used on the LV side of the gap and provides several supply functions: 1. Vcc supply for certain ICs directly, e.g IC202 comparator;
2. provides a voltage for the TR101,102 gate driver isolation transformers (also pulsed primaries with switching controlled by IC201); 3. It provides a feed to IC209 for creation of a reference +5V for Vcc of most all of the op amps and logic chips.
DCSW maybe means DCDC Converter Start/Shutdown Wire
SDW maybe means Sense Wire?
Last edited by kiev
on Sun Nov 01, 2020 4:35 pm, edited 3 times in total.
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