Other Parts Discussed in Thread: PMP22087, , TLV760
In reference to the PMP22087 reference design, I notice that the UCC256404 VCC is powered from a zener controlled linear regulator at ~20VDC. In the data sheet, most of the typical plots have VCC listed at 15VDC.
1. Why was a 24VDC winding used to create a ~20V supply to power VCC on the UCC256404 instead of providing it with a 15VDC supply?
2. Is a regulated supply required the VCC net? Why not use a Aux winding at 16V followed by a diode or a low cost bridge rectifier followed by a capacitor (or RC Network) instead?
3. If regulation is required, why not use a TLV760 with fixed 15V output following the rectifier stage?
Thanks in advance,
Cody