TECHNICAL FIELD

The present embodiments relate generally to electrical power supplies, and more particularly to a method and apparatus for pulse frequency modulation with discontinuous voltage sensing.

BACKGROUND

DC-DC converters sometimes use discontinuous output voltage sensing. Examples include “high side” buck and “primary sensing” flyback topologies. These topologies can be used with universal AC input voltage (e.g., 85V AC to 265V AC) where low “standby” and “no load” input power consumption (PIN,min) may be regulated and mandated by national and international standards. Pulse frequency modulation (“PFM”) in systems using continuous output voltage sensing can demonstrate desirable efficiency under light electrical load. A light-load efficiency may enable low minimum input power (“PIN,min”) for more efficient low power or “standby” modes for electrical or electronic devices. However, discontinuous VOUT sensing impacts usage of PFM operation, because PFM systems compatible with continuous VOUT sensing are not compatible with discontinuous VOUT sensing. Two types of parts and configurations are conventionally available. First, parts that can achieve low PIN must operate with large COUT (optimized for low PIN only). Second, parts that cannot achieve low PIN while in operation use small COUT (optimized for low total BOM cost only). Thus, there exists a need for achieving, in discontinuous output voltage sensing DC-DC converters, light load efficiency associated with continuous output voltage systems with PFM.

SUMMARY

The present embodiments relate to methods and apparatuses for controlling DC-DC converters, for example a PFM control method for DC-DC regulators using discontinuous VOUT sensing. Present embodiments relate to pulse frequency modulation control for DC-DC regulators using discontinuous output voltage sensing, where input power in “standby” and “no load” modes can be adjusted or adjustably set by varying characteristics of various electrical components. Various electrical components include, but are not limited to, capacitors, resistors, inductors, AND gates, OR gates, NOT gates, amplifiers, operational amplifiers, comparators, transistors, and the like.

Exemplary embodiments may include a method of applying a charging pulse to an output capacitor, detecting satisfaction of a charging threshold, ending the charging pulse in response to the detecting the satisfaction of the charging threshold, and discharging the sampling capacitor in response to the detecting the satisfaction of the charging threshold. Exemplary embodiments may also include an apparatus with a controller coupled to an input node, a timer coupled to the controller, an inductive charger coupled to the controller, to an input node, and to an output node, and a sensor coupled to the controller and the output node. Exemplary embodiments may further include an apparatus where a sensor with a sampling capacitor has a first terminal coupled to the output node and a second terminal coupled to the controller and the inductive charger.

