Power-on reset circuit with reset transition delay

摘要

A power-on-reset (POR) circuit for CMOS logic is operable to transition between a POR_active state and a POR_inactive state and can include: (a) VDD/VT threshold circuitry to provide a Vtp_threshold voltage based on input Vdd and PMOS Vtp, and a Vtn_threshold voltage based on input Vdd and NMOS Vtn; (b) POR transition detect circuitry to provide a POR_transition signal (active/inactive) based on a function(Vtp,Vtn), which is a function of Vtp_threshold and Vtn_threshold; and (c) POR transition control circuitry to provide the POR_state signal (active/inactive) based on the POR_transition signal. For a POR out-of-reset transition, the POR transition detect circuitry to switch the POR_transition signal inactive based on the function (Vtp,Vtn) corresponding to the POR_inactive state, and the POR transition control circuitry, responsive to the POR_transition signal switching to inactive, to initiate a POR out-of-reset delay period, and to signal the POR_inactive state after the POR out-of-reset delay period.