Apple patents power circuit that recovers wasted energy in devices
Apple describes a power supply design called a flyback converter that uses three switches to manage energy flow. It captures leftover energy that usually dissipates as heat and redirects it back into the system to improve efficiency.
In the filing’s own words
Operating a plurality of switching devices of a flyback converter by control circuitry of the flyback converter can include operating a main switch at a fixed frequency to alternately store energy in a flyback transformer when the main switch is turned on and deliver energy from the flyback transformer to an output when the main switch is turned off; operating a voltage clamp switch complementarily to the main switch to clamp a voltage across a primary winding of the flyback transformer while the flyback converter is delivering energy to the output; and operating a reverse current switch to recover leakage energy in the flyback converter by turning on the reverse current switch while the voltage clamp switch is turned on and after energy stored in the flyback transformer is delivered to the output and turning off the reverse current switch with turning off with the voltage clamp switch.
What exactly they claim (claim 1)
1. A flyback converter comprising: flyback converter circuitry including a flyback transformer having a primary winding coupled to a secondary winding and a main switch that alternately turns on to store energy from an input coupled to the primary winding in the flyback transformer and turns off deliver energy from the flyback transformer to an output coupled to the secondary winding; a voltage clamp circuit coupled to the flyback transformer, the voltage clamp circuit including a diode and a voltage clamp switch, wherein the voltage clamp switch operates complementarily to the main switch; a reverse current circuit coupled to the flyback transformer, the reverse current circuit including one or more snubber capacitors, one or more diodes, and a reverse current control switch, wherein the reverse current control switch operates in conjunction with the voltage clamp switch to recover leakage energy from the flyback converter circuitry; and control circuitry that provides drive signals to the main switch, voltage clamp switch, and reverse current control switch such that: the main switch operates at a fixed frequency and the control circuitry varies a duty cycle of the main switch to regulate an output voltage delivered to the output; the voltage clamp switch operates complementarily to the main switch; and the reverse current control switch turns on after energy stored in the flyback transformer is delivered to the output and a voltage of the primary winding is clamped by the voltage clamp circuit and turns off with the voltage clamp switch.
Facts
- Company
- Apple (Apple Inc.)
- Official title
- FLYBACK CONVERTER WITH IMPROVED LIGHT LOAD EFFICIENCY
- Publication number
- US20260291394A1
- Application number
- 19082656
- Filed
- Mar 18, 2025
- Published
- Sep 24, 2026
- Inventors
- 3
- Claims
- 20
Classified under
H02M 3/3353 Electricity & electronicsH02M 1/34 Electricity & electronicsMore from Apple in Chips & hardware
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Summaries are simplified from the filing’s own abstract and first claim. A patent filing is not a product announcement.
Patent data and drawings: U.S. Patent and Trademark Office (USPTO). Nebula is not affiliated with or endorsed by the USPTO.