Tool/software: TINA-TI or Spice Models
I have a 12V TO 5V 500kHz synchronous buck converter compensator followed by a PWM generator comparator producing 3.3V true and complementary PWM outputs into HI and HL of the UCC27712, which is used to drive high- and low-side NFETs. The boost circuitry on HB, HS, HO, and LO follow the UCC27712 datasheet example very closely and the circuit simulates fine much of the time. However, with what should be trivial circuit changes I get unexpected simulation results. For example, when I change the datasheet boost diode from a 600V to a similar 50V part the UCC27712 outputs never begin changing in response to the complementary PWM inputs and the circuit essentially flat lines through the entire simulation. With minor circuit tweaks, the UCC27712 outputs sometimes toggle and the buck converter works, but the USS27712 occasionally skips cycles, apparently at random. Am I missing something fundamental about the part operation, or is this, perhaps, a simulator or model problem?
