I use the MPM3515 supplied by +10V to generate -13V output. The enable is shifted as per buck’s GND. Its output is biased to +0.5V by the load before buck startup. But above 70°C case (thermo cam) the buck does not start even EN is at 2V (max rising threshold is 1.7V). VCC remains OFF. Measurements showed negative voltage (-0.5V) at the (internal) VCC pin. Is there any function inhibiting the VCC regulator’s startup under certain conditions?