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In place of the 150V supplied by the battery, another 12V source (or any lower voltage source) can be used to connect to the HV line. The precharge functions should be tested with a lower voltage first, remember to recalculate the voltage division values to see when precharge stops.
Before plugging in the capacitors or the HV (12V or similar in this case) to the board, enable precharge via the enable pin and probe the Vin+ pin on the isolated DC/DC and the Vcc pin on the opto-isolater. If the load switch is working correctly, there should be a 12V reading at these points.
Isolated DC/DC:
Still before plugging in the capacitors and HV, enable precharge and probe the test points ISO_1, ISO_2 and DISC_GATE. These should all be reading a 12V signal. If ISO_1 or ISO_2 isn't reading properly, double-check the pins on the isolated DC/DC U9 aren't shorted and connectivity between components is good. If DISC_GATE isn't reading, do the same with charge pump DC/DC U4.
Precharge Test points:
Connect the HV line (12V or similar) and the capacitors.
The first point to test is the capacitor itself. Enable precharge and measure of the change in voltage over the duration of the capacitor's charge. It should follow the expected curve of voltage in an RC circuit. Now unpower the enable pin and check the discharge normally.
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Repeat this test, except instead of checking the voltage on the capacitor, measure the test points COMP_OUT, AND_OUT, ISO_LATCH_OUT, and LATCH_OUT, and ISO_2. The latter 3 4 should all be logic low to start and only send a 12V signal only when the condition above is met. COMP_OUT will probably output a logic high when both pins are unpowered at the start. Note the times taken for each output to reach logic high. Also check the behaviour of LATCH_OUT to ensure it doesn't oscillate during the transition from logic high to logic low.
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