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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. Note the time taken to fully charge the capacitors. It should follow the expected curve of voltage in an RC circuit. Now unpower the enable pin and check measure the discharge normally. . The times taken should be similar:
Precharge Discharge (Note: should be flipped as this is the charge graph)
Next point to test is the voltage on the capacitor side of the precharge circuit and at the IN+ pin of the comparator alongside the comparator output test point. When using 12V in place of the 150V, the voltage at the IN- should be 0.75V. Then the voltage on the capacitor side should be around 11.45V when IN+ exceeds IN-. Check that the capacitor stops precharging when the voltage on the capacitor side indeed reaches around 11.45V and the IN+ pin reaches 0.75V.
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