Bi-directional communication scheme between primary and secondary for fly-back AC-DC converters

1 . A method for a secondary-side controlled Universal Serial Bus Power Delivery (USB-PD) converter, the method comprising:

a secondary-side controller, of the USB-PD converter, generating a first control signal;

a primary-side controller, of the USB-PD converter, receiving the first control signal via a first transformer of the USB-PD converter;

the primary-side controller activating or deactivating a first primary-side switch coupled to a primary winding of a second transformer of the USB-PD converter in response to the primary-side controller receiving the first control signal via the first transformer;

the primary-side controller generating a first acknowledgement signal in response to the generating a first signal for activating or deactivating the first primary-side switch;

the secondary-side controller receiving the first acknowledgement signal via the first transformer,

wherein the primary-side controller comprises an acknowledgement generator including gate drivers that drive first and second switches connected in series between a supply voltage and a primary-side ground, the acknowledgement generator being configured to produce distinct high-voltage and low-voltage pulse acknowledgements across the first transformer by opening and closing the first and second switches.

2 . The method of claim 1 :

wherein the first control signal comprises a pulse signal;

wherein the first acknowledgment signal comprises a pulse signal.

3 . The method of claim 1 :

wherein the primary-side controller activates the first primary-side switch in response to the primary-side controller receiving the first control signal via the first transformer;

wherein the method further comprises:

the secondary-side controller generating a second control signal;

the primary-side controller receiving the second control signal via the first transformer;

the primary-side controller deactivating the first primary-side switch in response to the primary-side controller receiving the second control signal via the first transformer;

the primary-side controller generating a second acknowledgement signal in response to the primary-side controller receiving the second control signal via the first transformer;

the secondary-side controller receiving the second acknowledgement signal via the first transformer.

4 . The method of claim 3 :

wherein the first and second control signals are positive and negative voltage pulse signals, respectively;

wherein the first and second acknowledgement signals are positive and negative voltage pulse signals, respectively.

5 . The method of claim 3 further comprising:

the secondary-side controller activating a secondary-side switch coupled to a secondary winding of the second transformer in response to the secondary-side controller receiving the second acknowledgement signal via the first transformer;

the primary-side controller activating the first primary-side switch while the secondary-side switch is activated;

the primary-side controller generating a third acknowledgement signal in response to the primary-side controller activating the first primary-side switch while the secondary-side switch is activated;

the secondary-side controller receiving the third acknowledgment signal via the first transformer while the secondary-side switch is activated;

the secondary-side controller deactivating the secondary-side switch in response to the secondary-side controller receiving the third acknowledgment signal via the first transformer.

6 . The method of claim 1 further comprising:

the secondary-side controller generating a second control signal;

the secondary-side controller generating a third control signal in response to the secondary-side controller not receiving an acknowledgement signal within a predetermined amount of time after the secondary-side controller generates the second control signal.

7 . The method of claim 4 further comprising:

the secondary-side controller generating a negative voltage control signal;

the primary-side controller receiving the negative voltage control signal via the first transformer;

the secondary-side controller generating a positive voltage control signal in response to the secondary-side controller receiving a third acknowledgement signal from the primary-side controller via the first transformer within a predetermined amount of time after the secondary-side controller generates the negative voltage control signal;

the primary-side controller receiving the positive voltage control signal via the first transformer;

the primary-side controller activating a second primary-side switch (HIGH SIDE CLAMP FET) coupled to the primary winding in response to the primary-side controller receiving the positive voltage control signal via the first transformer;

the secondary-side controller generating another negative voltage control signal when the secondary-side controller does not receive the third acknowledgement signal from the primary-side controller via the first transformer within the predetermined amount of time after the secondary-side controller generates the negative voltage control signal.

8 . The method of claim 1 further comprising:

wherein the primary-side controller activates the first primary-side switch in response to the primary-side controller receiving the first control signal via the first transformer;

wherein the method further comprises:

wherein the primary-side controller deactivates the first primary-side switch in response to the primary-side controller receiving a second control signal via the first transformer;

the primary-side controller measuring a voltage across current terminals of a second primary-side switch;

the primary-side controller comparing the measured voltage to a predefined voltage range;

the secondary-side controller adjusting a duration of time period during which the first primary-side switch is activated in a subsequent cycle in response to the primary controller determining the measured voltage is not in the predefined voltage range.

9 . A Universal Serial Bus Power Delivery (UDB-PD) power converter comprising:

a pulse transformer;

a secondary-side controller in data communication with the pulse transformer;

a primary-side controller in data communication with the pulse transformer;

wherein the secondary-side controller is configured to generate control signals;

wherein the secondary-side controller is configured to receive acknowledgement signals from the primary-side controller via the pulse transformer;

wherein the primary-side controller is configured to generate the acknowledgment signals;

wherein the primary-side controller is configured receive the control signals from the secondary-side controller via the pulse transformer,

wherein the primary-side controller generates an acknowledgement signal in response to generating a first signal for activating or deactivating a first primary-side switch; and wherein the primary-side controller comprises an acknowledgement generator including gate drivers that drive first and second switches connected in series between a supply voltage and a primary-side ground, the acknowledgement generator being configured to produce distinct high-voltage and low-voltage pulse acknowledgements across the pulse transformer by opening and closing the first and second switches.

10 . The USB-PD power converter of claim 9 further comprising:

a flyback transformer comprising a primary winding and a secondary winding;

a first primary-side switch connected to the primary winding and controlled by the primary-side controller based on control signals the primary-side controller receives from the secondary-side controller via the pulse transformer;

a secondary-side switch connected to the secondary winding and controlled by the secondary-side controller based on acknowledgment signals received from the primary-side controller via the pulse transformer.

11 . The USB-PD power converter of claim 10 :

wherein the primary-side controller is configured to receive a first control signal from the secondary-side controller via the pulse transformer;

wherein the primary-side controller is configured to activate or deactivate the first primary-side switch in response to the primary-side controller receiving the first control signal via the pulse transformer;

wherein the primary-side controller is configured to generate a first acknowledgement signal in response to generating a first signal for activating or deactivating the first primary-side switch;

wherein the secondary-side controller is configured to receive the first acknowledgement signal via the pulse transformer.

12 . The USB-PD power converter of claim 11 :

wherein the first control signal comprises a one of a positive voltage pulse signal and a negative voltage pulse signal;

wherein the first acknowledgment signal comprises a one of a positive voltage pulse signal and a negative voltage pulse signal.

13 . The USB-PD power converter of claim 11 :

wherein the primary-side controller is configured to activate the first primary-side switch in response to the primary-side controller receiving the first control signal via the pulse transformer;

wherein the secondary-side controller is configured to generate a second control signal;

wherein the primary-side controller is configured to receive the second control signal via the pulse transformer;

wherein the primary-side controller is configured to deactivate the first primary-side switch in response to the primary-side controller receiving the second control signal via the pulse transformer;

wherein the primary-side controller is configured generate a second acknowledgement signal in response to the primary-side controller receiving the second control signal via the pulse transformer;

wherein the secondary-side controller is configured to receive the second acknowledgement signal via the pulse transformer.

14 . The USB-PD power converter of claim 13 :

wherein the first and second control signals are positive and negative voltage pulse signals, respectively;

wherein the first and second acknowledgement signals are positive and negative voltage pulse signals, respectively.

15 . The USB-PD power converter of claim 13 :

wherein the secondary-side controller is configured to activate a secondary-side switch coupled to a secondary winding of the flyback transformer in response to the secondary-side controller receiving the second acknowledgement signal via the pulse transformer;

wherein the primary-side controller is configured to activate the first primary-side switch while the secondary-side switch is activated;

wherein the primary-side controller is configured to generate a third acknowledgement signal in response to the primary-side controller activating the first primary-side switch while the secondary-side switch is activated;

wherein the secondary-side controller is configured to receive the third acknowledgment signal via the pulse transformer while the secondary-side switch is activated;

wherein the secondary-side controller is configured to deactivate the secondary-side switch in response to the secondary-side controller receiving the third acknowledgment signal via the pulse transformer.

16 . The USB-PD power converter of claim 11 :

wherein the secondary-side controller is configured to generate a second control signal;

wherein the secondary-side controller is configured to generate a third control signal in response to the secondary-side controller not receiving an acknowledgement signal within a predetermined amount of time after the secondary-side controller generates the second control signal.

17 . The USB-PD power converter of claim 14 further comprising:

wherein the secondary-side controller is configured to generate a negative voltage control signal;

wherein the primary-side controller is configured to receive the negative voltage control signal via the pulse transformer;

wherein the secondary-side controller is configured to generate a positive voltage control signal in response to the secondary-side controller receiving a third acknowledgement signal from the primary-side controller via the pulse transformer within a predetermined amount of time after the secondary-side controller generates the negative voltage control signal;

wherein the primary-side controller is configured to receive the positive voltage control signal via the pulse transformer;

wherein the primary-side controller is configured to activate a second primary-side switch coupled to the primary winding in response to the primary-side controller receiving the positive voltage control signal via the pulse transformer;

wherein the secondary-side controller is configured to generate another negative voltage control signal when the secondary-side controller does not receive the third acknowledgement signal from the primary-side controller via the pulse transformer within the predetermined amount of time after the secondary-side controller generates the negative voltage control signal.

18 . The USB-PD power converter of claim 11 :

wherein the primary-side controller is configured to activate the first primary-side switch in response to the primary-side controller receiving the first control signal via the pulse transformer;

wherein the primary-side controller is configured to deactivate the first primary-side switch in response to the primary-side controller receiving a second control signal via the pulse transformer;

wherein the primary-side controller is configured to measure a voltage across current terminals of a second primary-side switch;

wherein the primary-side controller is configured to compare the measured voltage to a predefined voltage range;

wherein the secondary-side controller is configured to adjust a duration of time period during which the first primary-side switch is activated in a subsequent cycle in response to the primary controller determining the measured voltage is not in the predefined voltage range.

19 . A Universal Serial Bus Power Delivery (USB-PD) power adapter comprising:

a USB-C port;

a flyback transformer coupled to the USB-C port;

a pulse transformer;

a primary-side controller coupled to the pulse transformer and configured to control operation of the flyback transformer; and

a secondary-side controller coupled to the USB-C port and to the pulse transformer, the secondary-side controller configured for data communication with the primary-side controller in the USB-PD power adapter via the pulse transformer;

wherein the secondary-side controller is configured to generate control signals for indirectly controlling switches connected to a primary winding of the flyback transformer;

wherein the secondary-side controller is configured to receive acknowledgement signals from the primary-side controller via the pulse transformer;

wherein the secondary-side controller is configured to control a secondary-side switch connected to a secondary winding of the flyback transformer based on acknowledgment signals received from the primary-side controller via the pulse transformer

wherein the primary-side controller generates an acknowledgement signal in response to generating a first signal for activating or deactivating a first primary-side switch; and wherein the primary-side controller comprises an acknowledgement generator including gate drivers that drive first and second switches connected in series between a supply voltage and a primary-side ground, the acknowledgement generator being configured to produce distinct high-voltage and low-voltage pulse acknowledgements across the pulse transformer by opening and closing the first and second switches.