US 12,451,796 B2
Bootstrapped power switch for a negative buck-boost low-side
Michael Couleur, Rottach-Egern (DE); and Bhanupriya Suresh, Munich (DE)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Sep. 25, 2023, as Appl. No. 18/473,751.
Prior Publication US 2025/0105743 A1, Mar. 27, 2025
Int. Cl. H02M 1/08 (2006.01); H02M 1/36 (2007.01); H02M 3/07 (2006.01); H02M 3/158 (2006.01)
CPC H02M 1/08 (2013.01) [H02M 3/07 (2013.01); H02M 3/1582 (2013.01); H02M 3/071 (2021.05)] 20 Claims
OG exemplary drawing
 
1. An apparatus comprising:
a power converter configured to generate a negative voltage, the power converter including:
an inductor coupled between a ground node and a switching node;
a low-side switch coupled between the switching node and a negative voltage node, wherein the power converter is configured to generate the negative voltage on the negative voltage node;
a capacitor, wherein a voltage rating of the capacitor is less than a magnitude of the negative voltage; and
a control circuit configured to, during a first phase, cause the capacitor to accumulate a charge, and during a second phase, cause activation of the low-side switch by causing the capacitor to transfer a portion of the charge to a parasitic capacitance of the low-side switch.