Flyback converter with edge-based isolated communication
AssigneeDialog Semiconductor GmbH
InventorsWenduo Liu, Kun Yang, Laiqing Ping
Life of this patent
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Abstract
A flyback converter communication channel is provided that comprises a pair of capacitors. A transmitter on a first side of a transformer for the flyback converter transmits a transmitter signal over a first one of the capacitors. The transmitter also transmits a complement of the transmitter signal over a second one of the capacitors. A receiver on a second side of the transformer controls a switch transistor responsive to a high-pass-filtered difference of the received signals from the pair of capacitors.
Claims15
A receiver for a flyback converter, comprising;
- a synchronous rectifier switch transistor coupled to a secondary winding of a transformer for the flyback converter;
- a buffer for buffering an input signal to form a first voltage signal;
- an inverter for inverting the input signal to form a complement of the first voltage signal;
- a comparator having a first input and a second input;
- a first resistor and a second resistor connected in series between the first input and the second input;
- a first capacitor connected to the first resistor to form a first high-pass filter configured to high-pass filter the first voltage signal to form a first filtered signal;
- and
- a second capacitor connected to the second resistor to form a second high-pass filter configured to high-pass filter the complement of the first voltage signal to form a second filtered signal;
- wherein the comparator is configured to assert a receiver signal responsive to a difference between the first filtered signal and the second filtered signal exceeding a positive threshold voltage and configured to ground the receiver signal responsive to the difference being less than a negative threshold voltage, and wherein the receiver is further configured to control a switching of the synchronous rectifier switch transistor responsive to the receiver signal.
9-14. (canceled)
A method of controlling a switch in a flyback converter, comprising:
- in a transmitter on a first side of a transformer in the flyback converter, transmitting a pulsed signal across a first capacitor to a first input of a comparator, wherein a serial combination of a first resistor and a second resistor couples from the first input of the comparator to a second input of the comparator;
- transmitting a complement of the pulsed signal from the transmitter across a second capacitor to the second input of the comparator;
- high-pass filtering a first signal received from the first capacitor to form a first filtered signal;
- high-pass filtering a second signal received from the second capacitor to form a second filtered signal;
- in the comparator, comparing the first filtered signal to the second filtered signal to assert a receiver signal to a power supply voltage responsive to a difference between the first filtered signal and the second filtered signal exceeding a positive threshold voltage;
- grounding the receiver signal responsive to the difference between the first filtered signal and the second filtered signal being less than a negative threshold voltage;
- and
- controlling a switch transistor on the second side of the transformer responsive to whether the receiver signal is asserted or grounded.
Dependencies are inferred from the claim text.