When the converter input voltage rail (PVIN) ramps up, capacitive coupling through the parasitic gate-to-drain capacitance (C gd) could pull up on the gate of S1 and turn it on. A pulldown resistor on ...

Read this article online. The circuit in Figure 1 allows you to convert capacitance into a pulse train by using a constant current source and a linear monostable formed by two NAND-gate chips ...