Methods and apparatus to detect l2 entry and reset in universal serial bus repeaters

Abstract

An example apparatus includes: a pullup circuit coupled to a first USB terminal; a first pulldown circuit coupled to the first USB terminal; a second pulldown circuit coupled to a second USB terminal; a third pulldown circuit coupled to a third USB terminal; a fourth pulldown circuit coupled to a fourth USB terminal; a high-speed termination detection circuit including: a current source including a first supply terminal and a second supply terminal, the first supply terminal coupled to the first USB terminal, the second supply terminal coupled to the second USB terminal; a first comparator including a first comparator terminal and a second comparator terminal, the first comparator terminal coupled to the first USB terminal; and a second comparator including a third comparator terminal and a fourth comparator terminal, the third comparator terminal coupled to the second USB terminal; and a controller including a first control terminal and a second control terminal, the first control terminal coupled to the second comparator terminal, the second control terminal coupled to the fourth comparator terminal.