US 11,942,940 B2
Boot capacitor charge during low power states
Aaron Shreeve, Austin, TX (US); Chun Cheung, Milpitas, CA (US); Michael Jason Houston, Cary, NC (US); and Mehul Shah, Cary, NC (US)
Assigned to Renesas Electronics America Inc., Milpitas, CA (US)
Filed by Renesas Electronics America Inc., Milpitas, CA (US)
Filed on Jun. 11, 2021, as Appl. No. 17/345,317.
Claims priority of provisional application 63/146,230, filed on Feb. 5, 2021.
Prior Publication US 2022/0255537 A1, Aug. 11, 2022
Int. Cl. H03K 3/012 (2006.01); H03K 17/687 (2006.01)
CPC H03K 3/012 (2013.01) [H03K 17/6871 (2013.01); H03K 2217/0063 (2013.01); H03K 2217/0072 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a controller configured to:
detect a signal level of a three-level pulse width modulation (PWM) control signal, wherein the signal level varies among a low level, a middle level, and a high level;
enable a low power state of a device, the device comprising a high side switching element and a low side switching element driven by the three-level PWM control signal;
detect a lapse of a hand off time, wherein the hand off time is a duration in which the middle level of the three-level PWM control signal is sustained during the low power state of the device; and
in response to the detection of the lapse of the hand off time during the low power state of the device, and in response to the three-level PWM control signal transitioning to the low level during the low power state of the device, use the three-level PWM control signal to activate the low side switching element to charge a bootstrap capacitor of the device during the low power state of the device.