Patent ID: 9335772
Filing Date: 2016-05-10
CPC Classification: G05F,H02J,H02M

Claim Text:
1. A hold-up circuit coupled to a first node to receive an input voltage and to provide a hold-up voltage to the first node, the hold-up circuit comprising: an inductor coupled between the first node and a second node, the input voltage being provided to the first node; a constant on-time buck-boost control circuit configured to drive a high-side power switch and a low-side power switch to operate in a buck mode and a boost mode of operation, the low-side switch having a first current handling terminal coupled to the second node and a second current handling terminal coupled to a ground potential, the high-side switch having a first current handling terminal coupled to the second node and a second current handling terminal; and an energy storage capacitor coupled between the second current handling terminal of the high-side switch and the ground potential, wherein in response to the input voltage being greater than a predetermined threshold, the buck-boost control circuit is configured to drive the high-side and low-side power switches in the boost mode to charge the energy storage capacitor to a capacitor voltage greater than the input voltage; and in response to the input voltage being less than the predetermined threshold, the buck-boost control circuit is configured to drive the high-side and low-side power switches in the buck mode to supply the energy stored on the energy storage capacitor to the inductor to provide a regulated voltage as the hold-up voltage to the first node, the regulated voltage being less than the capacitor voltage.