Other Parts Discussed in Thread: UCC256404, UCC256402, UCC256403, TL431
On the EVM, when HV pin is tied to PGND and VCC supplied by an external source, the EVM doesn't function at VCC = 24V; but it does when VCC is 26V.
From the above, It looks like VCCstartself should be within 25V~28V.
What is the allowable input voltage range for VCC, including when powered from external supply.
The ABS MAX is 30V, so is the procedure to apply max 28V on startup, then shift to 13V~26V range for normal operation?
It should be possible to disable the X-Capacitor Discharge function on the UCC256404 by replacing the 5kΩ resistor with a larger value resistor, (basically severely limiting the input current to HV) but is there a maximum resistance that is allowed for such a non-typical use-case?
This question comes from a desire to stick with UCC256404 for DC input, because UCC256402/3 devices Vblk voltage ABS MAX is 7.2V, and their input voltage range resistor divider will go above this voltage at their peak input voltage.