	US 12,418,233 B2
	Boost inductor recirculation protection based on switch node detection method
Qiong Zou, Singapore (SG); and Soon Hwei Tan, Singapore (SG)
Assigned to Cypress Semiconductor Corporation, San Jose, CA (US)
Filed by Cypress Semiconductor Corporation, San Jose, CA (US)
Filed on May 23, 2023, as Appl. No. 18/322,419.
Claims priority of provisional application 63/399,359, filed on Aug. 19, 2022.
Prior Publication US 2024/0063719 A1, Feb. 22, 2024
Int. Cl. H02M 1/36 (2007.01); H02M 1/00 (2007.01); H02M 1/32 (2007.01); H02M 3/156 (2006.01); H02M 3/335 (2006.01)

CPC H02M 1/36 (2013.01) [H02M 1/0006 (2021.05); H02M 3/33507 (2013.01); H02M 1/32 (2013.01); H02M 3/156 (2013.01)]

20 Claims

1. A method of operating a switch mode power supply (SMPS), the method comprising:

following an initial startup of the SMPS, sensing an input voltage (V_IN) coupled through a boost-inductor to a switch pin (BSW-pin) of a primary integrated circuit (IC) in the SMPS by isolating a DC component (V_{DC_BSW}) of a switching voltage (V_BSW) coupled to the BSW-pin;

checking if V_INis greater than or equal to a minimum input voltage (V_{IN_MIN}) by comparing V_{DC_BSW}to a starting reference voltage (V_{REF_START}) in the primary IC; and

if V_{DC_BSW}is greater than or equal to V_{REF_START}:

operating a boost-converter to turn on boost-mode by cycling a boost-switch in the primary IC through which the BSW-pin is coupled to ground on and off to alternately store and discharge energy in the boost-inductor; and

boosting a supply voltage (Vcc) to a Vcc-pin of the primary IC coupled to the BSW-pin and boost-inductor through a rectifier and to ground though a capacitor on which Vcc is generated.