Flyback converter with reliable pulse-based isolated communication
AssigneeDialog Semiconductor GmbH
InventorsWenduo Liu, Kun Yang
Life of this patent
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Abstract
An isolated switching power converter communication channel is provided that comprises a pair of capacitors. A transmitter on a first side of a transformer for the 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 recovers a signal responsive to a high-pass-filtered difference of the received signals from the pair of capacitors.
Claims16
An isolated switching power converter, comprising;
- a ground-isolating communication channel spanning between a transmitter on a first side of a transformer for the isolated switching power converter and a receiver on a second side of the transformer, wherein the ground-isolating communication channel includes a first capacitor connected to a first resistor to form a first high-pass filter configured to high-pass filter a received clock pulse signal to form a first filtered signal and a second capacitor connected to a second resistor to form a second high-pass filter configured to high-pass filter a complement of the received clock pulse signal to form a second filtered signal;
- and wherein the receiver includes:
- a first comparator configured to assert a comparator output signal responsive to a difference between the first filtered signal and the second filtered signal;
- and
- a low-pass filter configured to low-pass filter the comparator output signal to form a low-pass filtered signal;
- and
- a second comparator configured to compare the low-pass filtered signal to a threshold voltage to form a recovered data signal, wherein the receiver is configured to switch on a switch transistor responsive to an assertion of the recovered data signal and to switch off the switch transistor responsive to the recovered data signal being grounded.
A method of controlling a switch in a flyback converter, comprising:
- in a controller on a first side of transformer in the flyback converter, asserting a gate control signal to control a cycling of a switch transistor on a second side of the transformer;
- while the gate control signal is asserted, transmitting a pulsed signal into a first capacitor and transmitting a complement of the pulsed signal into a second capacitor;
- 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;
- recovering a received pulsed signal responsive to a difference between the first filtered signal and the second filtered signal;
- low-pass filtering the received pulsed signal to form a low-pass filtered signal;
- and
- controlling the switch transistor on the second side of the transformer responsive to the low-pass filtered signal being greater than a threshold voltage, wherein the first side of the transformer is a primary-winding side of the transformer and the second side of the transformer is a secondary-winding side of the transformer, and wherein controlling the switch transistor comprises controlling a synchronous rectifier switch transistor.
Dependencies are inferred from the claim text.