公开(公告)号：US10193545B1

公开(公告)日：2019-01-29

申请号：US15687781

申请日：2017-08-28

Applicant: SILICON LABORATORIES INC.

Inventor： Erik Pankratz ,  Arnab Dutta

IPC: H03L7/00 ,  H03K17/22 ,  H03K19/0185 ,  H03K5/24

Abstract: A POR circuit for a secondary supply domain of an IC. A bias and reference circuit provides startup current and a reference voltage for a comparator. The comparator compares the reference voltage with a primary supply voltage and develops a bias current. The bias and reference circuit and the comparator includes a VGS loop which mirrors the bias current to develop the reference voltage. When the comparator switches, the bias current is at the low quiescent current level. A level shift and isolation circuit initially isolates a primary POR signal from the secondary domain. When the comparator switches, the primary POR signal is detected and level shifted to control the reset state. The delay circuit senses ramping of the secondary supply voltage and provides a delayed secondary POR signal a predetermined time period after the secondary supply voltage achieves a predetermined voltage threshold to additionally control the reset state.