Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
This action is in response to the application filed on 12/10/2024.
Claim Objections
Claims 2, 12, and 13 are objected to because of the following informalities: Regarding claim 2, in line 2, “the switching-mode converter” appears that it should read as “the isolated switching-mode converter”;in line 3, “the switching-mode converter” appears that it should read as “the isolated switching-mode converter”.
Regarding claim 12, in line 5, “the secondary-side controller” appears that it should read as “a secondary-side controller”;
in line 7, “the primary-side controller” appears that it should read as “a primary-side controller”,.
in line 13, “a primary transistor switch” appears that it should read as “the primary transistor switch”.
Regarding claim 13, in line 2, “the switching-mode converter” appears that it should read as “the isolated switching-mode converter”;in line 3, “the switching-mode converter” appears that it should read as “the isolated switching-mode converter”.
Appropriate correction is required.
Claim Rejections - 35 USC § 103
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries set forth in Graham v. John Deere Co., 383 U.S. 1, 148 USPQ 459 (1966), that are applied for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1, 3, 5, 6, 8, 9, 10, 11, 12, 14, 16, 17, and 19 are rejected under 35 U.S.C. 103 as being unpatentable over Wang et al. (US Patent Application Publication US 2015/0103567 A1, hereinafter “Wang”) in view of Hara (US Patent Application Publication US 2020/0169179 A1).
Regarding claim 1, Wang discloses (see Fig. 2) a control circuit (the controller comprising the primary logic circuit 201, isolation circuit 202, primary off detection circuit 203, secondary logic circuit 204, first comparison circuit 205, error amplifying circuit 206 and modulation signal generator 207) for controlling an isolated switching-mode converter (isolated switching converter 200), wherein the isolated switching-mode converter comprises a primary-side circuit (the circuit on the primary winding side including the primary switch MP), a secondary-side circuit (the circuit on the secondary winding side including the secondary switch MS) and a transformer (T1) coupled between the primary-side and secondary-side circuits, and wherein the control circuit comprises:
a primary-side controller (primary logic circuit 201) comprising an output terminal (output terminal of 201) that is electrically connected to a control terminal (gate) of a primary transistor switch (MP) in the primary-side circuit and is configured to output a control signal (CTRLP) for the primary transistor switch (see [0030] of Wang “the primary logic circuit 201 generates a primary control signal CTRLP to control the primary switch MP at the output terminal”); and
a secondary-side controller (secondary logic circuit 204) comprising an output terminal (output terminal of 204) that is electrically connected to a control terminal (gate) of a synchronous rectifier transistor (MS) in the secondary-side circuit and is configured to output a control signal (CTRLS) for the synchronous rectifier transistor (see [0028] of Wang “the secondary logic circuit 204 generates a secondary control signal CTRLS to control the secondary switch MS at the output terminal”); and wherein the primary-side controller controls the primary transistor switch (MP) in the primary-side circuit to be turned on after the synchronous rectifier transistor (MS) is turned off (see [0032] of Wang “to ensure the primary switch MP is turned on after the secondary switch is off, a delay circuit is coupled”).
Wang does not disclose wherein the primary-side controller detects, when receiving an inquiry signal from the secondary-side controller, a state of the primary transistor switch and if the primary transistor switch is turned off, the primary-side controller transmits a feedback signal to the secondary-side controller, and wherein the secondary-side controller controls the synchronous rectifier transistor to be turned off based on the feedback signal.
However, Hara teaches (see Fig. 3(b)) wherein the primary-side controller (primary-side control portion 10) detects, when receiving an inquiry signal (reference signal CMD2, sent by the secondary-side control portion 20) from the secondary-side controller (secondary-side control portion 20), a state of the primary transistor switch (switch transistor M1) and if the primary transistor switch is turned off, the primary-side controller transmits a feedback signal (response signal ACK1) to the secondary-side controller (see [0009] of Hara “send a predetermined second signal to the secondary-side control portion through the communication transformer when the switch transistor is turned off”; see [0069] of Hara “The signal S1 in response to the reference signal CMD2 received is specifically referred to as a response signal ACK1”), and wherein the secondary-side controller controls the synchronous rectifier transistor (SR transistor M2) to be turned off based on the feedback signal (see [0009] of Hara “The secondary-side control portion controls turn-on and turn-off of the synchronous rectification transistor according to the predetermined first signal and the predetermined second signal received”).
Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the control circuit of Wang to include the inquiry and feedback signaling, as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 3, Wang does not disclose wherein after controlling the synchronous rectifier transistor to be turned off based on the feedback signal, the secondary-side controller is further configured to transmit a first indication signal to the primary-side controller, thereby prompting the primary-side controller to turn on the primary transistor switch.
However, Hara teaches (see Fig. 3(a)) wherein after controlling the synchronous rectifier transistor (SR transistor M2) to be turned off, the secondary-side controller (secondary-side control portion 20) is further configured to transmit a first indication signal (response signal ACK2) to the primary-side controller (primary-side control portion 10), thereby prompting the primary-side controller to turn on the primary transistor switch (switch transistor M1) (see [0010] of Hara “the secondary-side control portion is configured to send a predetermined first response signal to the primary-side control portion through the communication transformer in response to the predetermined first signal received”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the control circuit of Wang to include transmitting the first indication signal as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 5, Wang does not disclose wherein the primary-side controller is further configured to transmit a second indication signal in case of the primary transistor switch being turned off, thereby prompting the secondary-side controller to control the synchronous rectifier transistor to be turned on.
However, Hara teaches (see Fig. 3(a)) wherein the primary-side controller (primary-side control portion 10) is further configured to transmit a second indication signal (predetermined second signal, S1) in case of the primary transistor switch (switch transistor M1) being turned off, thereby prompting the secondary-side controller (secondary-side control portion 20) to control the synchronous rectifier transistor (SR transistor M2) to be turned on (see [0009] of Hara “send a predetermined second signal to the secondary-side control portion through the communication transformer when the switch transistor is turned off”; see [0009] of Hara “The secondary-side control portion controls turn-on and turn-off of the synchronous rectification transistor according to the predetermined first signal and the predetermined second signal received”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the control circuit of Wang such that the primary-side controller transmits the second indication signal in case of the primary transistor switch being turned off, as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 6, Wang does not disclose wherein the secondary-side controller is further configured to detect a voltage signal from a secondary-side winding in the transformer and to control the synchronous rectifier transistor to be turned on when the voltage signal from the secondary-side winding drops to a predetermined value as a result of the primary transistor switch being turned off.
However, Hara teaches (see Fig. 1) wherein the secondary-side controller (secondary-side control portion 20) is further configured to detect a voltage signal (voltage VA, a divided voltage of the drain voltage VDR of the SR transistor M2 at the secondary-side winding W2) from a secondary-side winding (W2) in the transformer (TR) and to control the synchronous rectifier transistor (SR transistor M2) to be turned on when the voltage signal from the secondary-side winding drops to a predetermined value (the negative turn-on determination voltage) as a result of the primary transistor switch (switch transistor M1) being turned off (see [0049] of Hara “turns on the SR transistor M2 when the voltage VA received becomes lower than a predetermined negative turn-on determination voltage”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the control circuit of Wang such that the secondary-side controller turns on the synchronous rectifier transistor when the secondary-side winding voltage drops to a predetermined value, as taught by Hara, because it can help control the synchronous rectifier transistor while the primary transistor switch and the synchronous rectifier transistor are not simultaneously turned on to prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 8, Wang discloses (see Fig. 2) the secondary-side controller comprising a first logic control module (secondary logic circuit 204), wherein a first output terminal of the first logic control module (output terminal of 204) is electrically connected to the control terminal (gate) of the synchronous rectifier transistor (MS) and is configured to provide the control signal (CTRLS) to the synchronous rectifier transistor (see [0028] of Wang “the secondary logic circuit 204 generates a secondary control signal CTRLS to control the secondary switch MS at the output terminal”).
Wang does not disclose a first transmitter module and a first receiver module, wherein a second output terminal of the first logic control module is electrically connected to the first transmitter module and is configured to transmit a generated signal to the primary-side controller via the first transmitter module, and a first input terminal of the first logic control module is electrically connected to the first receiver module and is configured to receive a signal from the primary-side controller via the first receiver module.
However, Hara teaches (see Fig. 2) a first transmitter module (secondary-side sending portion 35) and a first receiver module (secondary-side receiving portion 36), wherein a second output terminal (output terminal TM27) of the first logic control module (secondary-side control portion 20) is electrically connected to the first transmitter module (35) and is configured to transmit a generated signal (signal S2) to the primary-side controller (primary-side control portion 10) via the first transmitter module (35), and a first input terminal (input terminal TM26) of the first logic control module (20) is electrically connected to the first receiver module (36) and is configured to receive a signal (signal S1) from the primary-side controller (10) via the first receiver module (36) (see [0061] of Hara “the pulse transformer portion 30 includes pulse transformers 31 and 32, a primary-side sending portion 33, a primary-side receiving portion 34, a secondary-side sending portion 35 and a secondary-side receiving portion 36”; see [0054] of Hara “The terminal TM26 is an input terminal for receiving the signal S1 mentioned below, and the terminal TM27 is an output terminal for sending the signal S2”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to provide the secondary-side controller of Wang with the first transmitter module and the first receiver module as taught by Hara, because it can help establish bidirectional communication between the secondary-side controller and the primary-side controller across the isolation barrier, so that the synchronous rectifier transistor and the primary transistor switch are not turned on simultaneously and the system is protected from damage.
Regarding claim 9, Wang discloses (see Fig. 2) the primary-side controller comprising a second logic control module (primary logic circuit 201), wherein a first output terminal of the second logic control module (output terminal of 201) is electrically connected to the control terminal (gate) of the primary transistor switch (MP) and is configured to provide the control signal (CTRLP) to the primary transistor switch (see [0030] of Wang “the primary logic circuit 201 generates a primary control signal CTRLP to control the primary switch MP at the output terminal”).
Wang does not disclose a second receiver module and a second transmitter module, wherein an input terminal of the second logic control module is connected to the second receiver module and is configured to receive a signal from the secondary-side controller via the second receiver module, and a second output terminal of the second logic control module is electrically connected to the second transmitter module and is configured to transmit a generated signal to the secondary-side controller via the second transmitter module.
However, Hara teaches (see Fig. 2) a second receiver module (primary-side receiving portion 34) and a second transmitter module (primary-side sending portion 33), wherein an input terminal (input terminal TM17) of the second logic control module (primary-side control portion 10) is connected to the second receiver module (34) and is configured to receive a signal (signal S2) from the secondary-side controller (secondary-side control portion 20) via the second receiver module (34), and a second output terminal (output terminal TM16) of the second logic control module (10) is electrically connected to the second transmitter module (33) and is configured to transmit a generated signal (signal S1) to the secondary-side controller (20) via the second transmitter module (33) (see [0061] of Hara “the pulse transformer portion 30 includes pulse transformers 31 and 32, a primary-side sending portion 33, a primary-side receiving portion 34, a secondary-side sending portion 35 and a secondary-side receiving portion 36”; see [0053] of Hara “The terminal TM16 is an output terminal for sending a signal S1 mentioned below, and the terminal TM17 is an input terminal for receiving a signal S2”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to provide the primary-side controller of Wang with the second receiver module and the second transmitter module as taught by Hara, because it can help establish bidirectional communication between the secondary-side controller and the primary-side controller across the isolation barrier, so that the synchronous rectifier transistor and the primary transistor switch are not turned on simultaneously and the system is protected from damage.
Regarding claim 10, Wang discloses (see Fig. 2) an isolator (isolation circuit 202) coupled between the primary-side controller (primary logic circuit 201) and the secondary-side controller (secondary logic circuit 204) (see [0029] of Wang “the isolation circuit 202 generates a synchronous signal SYNC electrically isolated from the first comparison signal CMPO1 at the output terminal”).
Wang does not disclose wherein the isolator enables a signal from the secondary-side controller and a signal from the primary-side controller to be transmitted to one another. However, Hara teaches (see Fig. 1) wherein the isolator (pulse transformer portion 30) enables a signal (signal S2) from the secondary-side controller (secondary-side control portion 20) and a signal (signal S1) from the primary-side controller (primary-side control portion 10) to be transmitted to one another (see [0057] of Hara “The pulse transformer portion 30 is a communication transformer for implementing bi-directional communication between the primary-side control portion 10 and the secondary-side control portion 20, and is formed by more than one pulse transformer”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to configure the isolator of Wang to enable signals from the secondary-side controller and the primary-side controller to be transmitted to one another, as taught by Hara, because it can help provide communication in both directions between the primary-side and secondary-side controllers across a single isolation barrier while reducing the number of isolation components required.
Regarding claim 11, Wang does not disclose a first isolator and a second isolator, each coupled between the primary-side controller and the secondary-side controller, wherein the first isolator is configured to couple a signal from the secondary-side controller to the primary-side controller, and wherein the second isolator is configured to couple a signal from the primary-side controller to the secondary-side controller.
However, Hara teaches (see Fig. 2) a first isolator (pulse transformer 32) and a second isolator (pulse transformer 31), each coupled between the primary-side controller (primary-side control portion 10) and the secondary-side controller (secondary-side control portion 20), wherein the first isolator (32) is configured to couple a signal (signal S2) from the secondary-side controller to the primary-side controller (via the secondary-side sending portion 35 and the primary-side receiving portion 34), and wherein the second isolator (31) is configured to couple a signal (signal S1) from the primary-side controller to the secondary-side controller (via the primary-side sending portion 33 and the secondary-side receiving portion 36) (see [0061] of Hara “the pulse transformer portion 30 includes pulse transformers 31 and 32, a primary-side sending portion 33, a primary-side receiving portion 34, a secondary-side sending portion 35 and a secondary-side receiving portion 36”; see [0063] of Hara “the secondary-side sending portion 35 generates a pulse signal based on the signal S2b from the secondary-side control portion 20, and the pulse signal generated is applied to the secondary-side winding of the pulse transformer 32”; see [0062] of Hara “the primary-side sending portion 33 generates a pulse signal based on the signal S1a from the primary-side control portion 10, and applies the pulse signal generated to the primary-side winding of the pulse transformer 31”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to provide the control circuit of Wang with the first isolator and the second isolator as taught by Hara, because it can help provide a dedicated communication path for each direction between the primary-side and secondary-side controllers, thereby improving the reliability of the bidirectional communication across the isolation barrier.
Regarding claim 12, Wang discloses (see Fig. 2) a control method for an isolated switching-mode converter (isolated switching converter 200), wherein the isolated switching-mode converter comprises a primary-side circuit (the circuit including the primary switch MP), a secondary-side circuit (the circuit including the secondary switch MS) and a transformer (T1) coupled between the primary-side and secondary-side circuits, and wherein the control method comprises: at the primary-side controller (primary logic circuit 201), providing a turn-on signal (CTRLP) to a primary transistor switch (MP) in the primary-side circuit after the synchronous rectifier transistor (MS) is turned off, thereby controlling the primary transistor switch to be turned on (see [0030] of Wang “the primary logic circuit 201 generates a primary control signal CTRLP to control the primary switch MP at the output terminal”; see [0032] of Wang “to ensure the primary switch MP is turned on after the secondary switch is off, a delay circuit is coupled”); and at the secondary-side controller (secondary logic circuit 204), providing a turn-off signal (CTRLS) to a synchronous rectifier transistor (MS) in the secondary-side circuit, thereby controlling the synchronous rectifier transistor to be turned off (see [0028] of Wang “the secondary logic circuit 204 generates a secondary control signal CTRLS to control the secondary switch MS at the output terminal”).
Wang does not disclose: at the secondary-side controller, transmitting an inquiry signal to the primary-side controller; at the primary-side controller, receiving the inquiry signal and then detecting a state of a primary transistor switch, wherein in case of the primary transistor switch being turned off, transmitting a feedback signal to the secondary-side controller; and at the secondary-side controller, receiving the feedback signal and providing a turn-off signal to a synchronous rectifier transistor in the secondary-side circuit.
However, Hara teaches (see Fig. 3(b)): at the secondary-side controller (secondary-side control portion 20), transmitting an inquiry signal (reference signal CMD2) to the primary-side controller (primary-side control portion 10); at the primary-side controller, receiving the inquiry signal and then detecting a state of a primary transistor switch (switch transistor M1), wherein in case of the primary transistor switch being turned off, transmitting a feedback signal (response signal ACK1) to the secondary-side controller (see [0069] of Hara “The signal S1 in response to the reference signal CMD2 received is specifically referred to as a response signal ACK1”; see [0009] of Hara “send a predetermined second signal to the secondary-side control portion through the communication transformer when the switch transistor is turned off”); and at the secondary-side controller, receiving the feedback signal and providing a turn-off signal to a synchronous rectifier transistor (SR transistor M2) in the secondary-side circuit (see [0009] of Hara “The secondary-side control portion controls turn-on and turn-off of the synchronous rectification transistor according to the predetermined first signal and the predetermined second signal received”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang to include the inquiry and feedback signaling, as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 14, Wang does not disclose wherein the secondary-side controller further transmits, after controlling the synchronous rectifier transistor to be turned off based on the feedback signal, a first indication signal to the primary-side controller, wherein the primary-side controller controls the primary transistor switch to be turned on based on the first indication signal.
However, Hara teaches (see Fig. 3(a)) wherein the secondary-side controller (secondary-side control portion 20) further transmits, after controlling the synchronous rectifier transistor (SR transistor M2) to be turned off, a first indication signal (response signal ACK2) to the primary-side controller (primary-side control portion 10), wherein the primary-side controller controls the primary transistor switch (switch transistor M1) to be turned on based on the first indication signal (see [0010] of Hara “the secondary-side control portion is configured to send a predetermined first response signal to the primary-side control portion through the communication transformer in response to the predetermined first signal received”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang to include transmitting the first indication signal as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 16, Wang does not disclose wherein the primary-side controller further transmits a second indication signal when the primary transistor switch is turned off, and wherein the secondary-side controller provides, based on the second indication signal, the turn-on signal to the synchronous rectifier transistor, thereby controlling the synchronous rectifier transistor to be turned on.
However, Hara teaches (see Fig. 3(a)) wherein the primary-side controller (primary-side control portion 10) further transmits a second indication signal (predetermined second signal, S1) when the primary transistor switch (switch transistor M1) is turned off, and wherein the secondary-side controller (secondary-side control portion 20) provides, based on the second indication signal, the turn-on signal to the synchronous rectifier transistor (SR transistor M2) (see [0009] of Hara “send a predetermined second signal to the secondary-side control portion through the communication transformer when the switch transistor is turned off”; see [0009] of Hara “The secondary-side control portion controls turn-on and turn-off of the synchronous rectification transistor according to the predetermined first signal and the predetermined second signal received”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang such that the primary-side controller transmits the second indication signal when the primary transistor switch is turned off, as taught by Hara, because it can help reliably prevent the primary transistor switch and the synchronous rectifier transistor from being turned on simultaneously which helps prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 17, Wang does not disclose wherein the secondary-side controller detects a voltage signal from a secondary-side winding in the transformer and provides the turn-on signal to the synchronous rectifier transistor when the voltage signal from the secondary-side winding drops to a predetermined value as a result of the primary transistor switch being turned off.
However, Hara teaches (see Fig. 1) wherein the secondary-side controller (secondary-side control portion 20) detects a voltage signal (voltage VA, a divided voltage of the drain voltage VDR of the SR transistor M2 at the secondary-side winding W2) from a secondary-side winding (W2) in the transformer (TR) and provides the turn-on signal to the synchronous rectifier transistor (SR transistor M2) when the voltage signal from the secondary-side winding drops to a predetermined value (the negative turn-on determination voltage) as a result of the primary transistor switch (switch transistor M1) being turned off (see [0049] of Hara “turns on the SR transistor M2 when the voltage VA received becomes lower than a predetermined negative turn-on determination voltage”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang to turn on the synchronous rectifier transistor when the secondary-side winding voltage drops to a predetermined value, as taught by Hara, because it can help control the synchronous rectifier transistor while the primary transistor switch and the synchronous rectifier transistor are not simultaneously turned on to help prevent system damage (see [0005] of Hara “The switch transistor of the primary side and the synchronous rectification transistor of the secondary-side should be prevented from being turned on simultaneously, so as to prevent system damage”).
Regarding claim 19, Wang discloses (see Fig. 2) an isolated switching-mode converter (isolated switching converter 200) comprising the control circuit (the controller comprising 201-207) (see [0025] of Wang “The isolated switching converter 200 comprises a transformer T1, a primary switch MP, a secondary switch MS and a controller”). The isolated switching-mode converter comprising the control circuit of claim 1 is rejected under 35 U.S.C. 103 for the same reasons set forth in the rejection of claim 1 above.
Claims 2, 4, 13, and 15 are rejected under 35 U.S.C. 103 as being unpatentable over Wang in view of Hara and Guo et al. (US Patent Application Publication US 2022/0200466 A1, hereinafter “Guo”).
Regarding claim 2, Wang does not disclose wherein the secondary-side controller is configured to receive an output voltage of the switching-mode converter and to transmit the inquiry signal when the output voltage of the switching-mode converter is below a predetermined voltage.
However, Guo teaches (see Fig. 4) wherein the secondary-side controller is configured to receive an output voltage of the switching-mode converter (the feedback signal VFB of the output voltage VOUT) and to transmit the inquiry signal (the primary-side original turn-on signal PSO) when the output voltage of the switching-mode converter is below a predetermined voltage (the first reference Vref1) (see [0015] of Guo “if the feedback signal of the output voltage of the isolated power supply drops to the reference, generate the primary-side original turn-on instant signal”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to configure the secondary-side controller of Wang to transmit the inquiry signal when the output voltage is below a predetermined voltage, as taught by Guo, because it can help initiate a switching cycle to regulate the output voltage of the converter.
Regarding claim 4, Wang does not disclose wherein the primary-side controller is configured to control the primary transistor switch to be turned on after a predefined period of time following the transmission of the feedback signal, and wherein the predefined period of time ends later than a time when the synchronous rectifier transistor has been turned off.
However, Guo teaches (see Fig. 5A) wherein the primary-side controller (primary-side control signal generator 103) is configured to control the primary transistor switch to be turned on after a predefined period of time (the dead time Tdead set by the first delay circuit) following the transmission of the feedback signal, and wherein the predefined period of time ends later than a time when the synchronous rectifier transistor has been turned off (the turn-on instant of the primary-side transistor switch being the later of the supposed turn-on instant K1 or the synchronous-rectifier turn-off instant K2) (see [0033] of Guo “a first delay circuit configured to delay the turn-off instant of the secondary-side transistor switch and thereby reduce a dead time from the secondary-side transistor switch being turned off to the primary-side transistor switch being turned on”; see [0010] of Guo “the turn-on instant for the primary-side transistor switch from the second turn-on instant or the first turn-on instant whichever is later”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to control the primary transistor switch of Wang to be turned on after a predefined period of time ending later than the synchronous-rectifier turn-off, as taught by Guo, because it can help reliably avoid cross-conduction of the primary transistor switch and the synchronous rectifier transistor.
Regarding claim 13, Wang does not disclose wherein the secondary-side controller receives an output voltage of the switching-mode converter and transmits the inquiry signal when the output voltage of the switching-mode converter is below a predetermined voltage.
However, Guo teaches (see Fig. 4) wherein the secondary-side controller receives an output voltage of the switching-mode converter (the feedback signal VFB of the output voltage VOUT) and transmits the inquiry signal (the primary-side original turn-on signal PSO) when the output voltage of the switching-mode converter is below a predetermined voltage (the first reference Vref1) (see [0015] of Guo “if the feedback signal of the output voltage of the isolated power supply drops to the reference, generate the primary-side original turn-on instant signal”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang such that the secondary-side controller transmits the inquiry signal when the output voltage is below a predetermined voltage, as taught by Guo, because it can help initiate a switching cycle to regulate the output voltage of the converter.
Regarding claim 15, Wang does not disclose wherein the primary-side controller provides the turn-on signal to the primary transistor switch after a predefined period of time following transmission of the feedback signal, thereby turning on the primary transistor switch, wherein the predefined period of time ends later than a time when the synchronous rectifier transistor has been turned off.
However, Guo teaches (see Fig. 5A) wherein the primary-side controller (primary-side control signal generator 103) provides the turn-on signal to the primary transistor switch after a predefined period of time (the dead time Tdead set by the first delay circuit) following transmission of the feedback signal, wherein the predefined period of time ends later than a time when the synchronous rectifier transistor has been turned off (the turn-on instant being the later of the supposed turn-on instant K1 or the synchronous-rectifier turn-off instant K2) (see [0033] of Guo “a first delay circuit configured to delay the turn-off instant of the secondary-side transistor switch and thereby reduce a dead time from the secondary-side transistor switch being turned off to the primary-side transistor switch being turned on”; see [0010] of Guo “the turn-on instant for the primary-side transistor switch from the second turn-on instant or the first turn-on instant whichever is later”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang to provide the turn-on signal after a predefined period of time ending later than the synchronous-rectifier turn-off, as taught by Guo, because it can help reliably avoid cross-conduction of the primary transistor switch and the synchronous rectifier transistor.
Claims 7 and 18 are rejected under 35 U.S.C. 103 as being unpatentable over Wang in view of Hara and NCP43080 (“NCP43080 Synchronous Rectifier Controller,” Publication Order Number NCP43080/D, Rev. 0, ON Semiconductor, February 2017, hereinafter “NCP43080”).
Regarding claim 7, Wang does not disclose wherein the secondary-side controller is further configured to detect a secondary-side current in the secondary-side circuit and to control the synchronous rectifier transistor to be turned off when detecting that the secondary-side current drops to a first preset current during a turn-on period of the synchronous rectifier transistor.
However, NCP43080 teaches (see Fig. 39) wherein the secondary-side controller (the NCP43080 controller) is further configured to detect a secondary-side current (the secondary current sensed at the current-sense CS pin) in the secondary-side circuit and to control the synchronous rectifier transistor (SR MOSFET M1) to be turned off when detecting that the secondary-side current drops to a first preset current (the turn-off current threshold corresponding to VTH_CS_OFF) during a turn-on period of the synchronous rectifier transistor (see page 15 of NCP43080 “The SR MOSFET is turned-off as soon as the voltage on the CS pin is higher than VTH_CS_OFF”; see page 15 of NCP43080 “the turn-off current depends on MOSFET RDSON”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the control circuit of Wang such that the secondary-side controller turns off the synchronous rectifier transistor when the secondary-side current drops to a first preset current, as taught by NCP43080, because it can help allow the maximum synchronous rectification conduction time while preventing reverse current through the synchronous rectifier transistor.
Regarding claim 18, Wang does not disclose wherein the secondary-side controller further detects a secondary-side current in the secondary-side circuit and provides the turn-off signal to the synchronous rectifier transistor in the secondary-side circuit when detecting that the secondary-side current drops to a first preset current during a turn-on period of the synchronous rectifier transistor.
However, NCP43080 teaches (see Fig. 39) wherein the secondary-side controller (the NCP43080 controller) further detects a secondary-side current (the secondary current sensed at the current-sense CS pin) in the secondary-side circuit and provides the turn-off signal to the synchronous rectifier transistor (SR MOSFET M1) when detecting that the secondary-side current drops to a first preset current (the turn-off current threshold corresponding to VTH_CS_OFF) during a turn-on period of the synchronous rectifier transistor (see page 15 of NCP43080 “The SR MOSFET is turned-off as soon as the voltage on the CS pin is higher than VTH_CS_OFF”; see page 15 of NCP43080 “the turn-off current depends on MOSFET RDSON”). Therefore, it would have been obvious to a person having ordinary skill in the art before the effective filing date of the claimed invention to modify the method of Wang to turn off the synchronous rectifier transistor when the secondary-side current drops to a first preset current, as taught by NCP43080, because it can help allow the maximum synchronous rectification conduction time while preventing reverse current through the synchronous rectifier transistor.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure: US 2025/0007418 A1 discloses an isolated power supply control circuit with shoot-through prevention. US 2025/0192687 A1 discloses an isolated switching-mode converter control circuit with information exchange between the primary-side controller and the secondary-side controller.
US 2019/0245449 A1 discloses a secondary-side controller transmitting a wake-up request to a primary-side controller of a switching power converter.
US 2020/0412231 A1 discloses bidirectional communication between a primary-side controller and a secondary-side controller across a galvanic isolation barrier in a secondary-controlled flyback converter.
US 2014/0133186 A1 discloses primary-side and secondary-side controllers communicating bidirectionally through a magnetically coupled communication link, each controller coupled to a transmit circuit and a receive circuit.
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/MONICA LEWIS/ Supervisory Patent Examiner, Art Unit 2838
/JYE-JUNE LEE/Examiner, Art Unit 2838
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