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 10/09/2024.
Drawings
Figure 1 should be designated by a legend such as --Prior Art-- because only that which is old is illustrated. See MPEP § 608.02(g). Corrected drawings in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. The replacement sheet(s) should be labeled “Replacement Sheet” in the page header (as per 37 CFR 1.84(c)) so as not to obstruct any portion of the drawing figures. If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Figs. 1, 2, and 4 have illegible text that require correction.
Corrected drawing sheets in compliance with 37 CFR 1.121(d) are required in reply to the Office action to avoid abandonment of the application. Any amended replacement drawing sheet should include all of the figures appearing on the immediate prior version of the sheet, even if only one figure is being amended. The figure or figure number of an amended drawing should not be labeled as “amended.” If a drawing figure is to be canceled, the appropriate figure must be removed from the replacement sheet, and where necessary, the remaining figures must be renumbered and appropriate changes made to the brief description of the several views of the drawings for consistency. Additional replacement sheets may be necessary to show the renumbering of the remaining figures. Each drawing sheet submitted after the filing date of an application must be labeled in the top margin as either “Replacement Sheet” or “New Sheet” pursuant to 37 CFR 1.121(d). If the changes are not accepted by the examiner, the applicant will be notified and informed of any required corrective action in the next Office action. The objection to the drawings will not be held in abeyance.
Specification
The title of the invention is not descriptive. A new title is required that is clearly indicative of the invention to which the claims are directed, i.e. including a regulator circuit configured to regulate charging of a bootstrap capacitor during a time period when a high-side switching device is turned on.
Appropriate correction is required.
Claim Objections
Claims 2 and 9 are objected to because of the following informalities: Regarding claim 2, in line 4, “the pulse duration” appears that it should read as “the variable duration” in order to provide a clear antecedent basis. Regarding claim 9, in line 2-3, “the respective input of the comparator module” appears that it should read as “the input of the comparator module that receives the reference voltage” for clarity, since claim 7 introduces two inputs to the comparator module. Appropriate correction is required.
Claim Rejections - 35 USC § 102
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 the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1, 2, and 16 are rejected under 35 U.S.C. 102 (a)(1) as being anticipated by Chen et al. (US Patent Application Publication US 2014/0217959 A1, hereinafter “Chen”). Regarding claim 1, Chen discloses (see Fig. 2) a regulator circuit (auxiliary bootstrap circuit 224 together with controller 250) for use with circuitry that comprises a switching converter (synchronous switched-mode DC/DC converter 200) comprising at least a high-side switching device (high-side N-type MOSFET 202, also referred to as “Q1”) and a low-side switching device (low-side N-type MOSFET 204, also referred to as “Q2”) coupled in series between an input node (input node 208 receiving Vin) at an input voltage (Vin) and a reference node (ground), and further comprises a bootstrap capacitor (bootstrap capacitor 216, also referred to as “CBOOT”) coupled to the high-side switching device for supplying a drive voltage for operating the high-side switching device (see [0038] "bootstrap capacitor 116 is coupled between a boot node 118 and switch node 106 (i.e., the source of Q1), wherein boot node 118 of bootstrap capacitor 116 is used to bias driver circuit 110"; further see [0041]: equivalent nodes between Fig. 1 and Fig. 2 share like reference numerals, such that bootstrap capacitor 216 of Fig. 2 is correspondingly coupled between boot node 218 and switch node 206),
wherein the regulator circuit is configured to regulate charging of the bootstrap capacitor during a time period when the high-side switching device is turned on (see [0022] "the second operating mode is when the high-side switching MOSFET is ON and the low-side switching MOSFET is OFF"; further see [0047] "auxiliary bootstrap circuit 224 is also activated and used to refresh bootstrap capacitor 216 … the following discussion applies to all of the following scenarios: … (3) converter 200 is not under PWM switching with Q1 ON and Q2 OFF"), so as to compensate for a voltage drop across the bootstrap capacitor resulting from the high-side switching device being turned on (see [0038] "while powering driver circuit 110, bootstrap capacitor 116 discharges and voltage across capacitor 116 drops"; further see [0050] "controller 250 additionally monitors the voltage across bootstrap capacitor 216 … When controller 250 detects that the bootstrap capacitor voltage is less than the predetermined threshold voltage, controller 250 determines that refresh is needed, and subsequently activates auxiliary bootstrap circuit 224").
Regarding claim 2, Chen discloses (see Fig. 2) wherein the regulator circuit is configured to, when the high-side switching device is turned on (see [0047] "converter 200 is not under PWM switching with Q1 ON and Q2 OFF"), generate a control pulse of a variable duration (enable signal EN 236 generated by controller 250, which is asserted when V_CBOOT falls below the threshold and de-asserted when V_CBOOT recovers above the threshold, see [0050] "When controller 250 detects that the bootstrap capacitor voltage is less than the predetermined threshold voltage, controller 250 determines that refresh is needed, and subsequently activates auxiliary bootstrap circuit 224"; further see Fig. 3 (steps 304, 306, 308), where the duration between activation and deactivation of the auxiliary bootstrap circuit varies based on when V_CBOOT crosses the threshold), so as to couple the drive voltage to a supply voltage higher than the input voltage during the pulse duration (see [0048] "bootstrap capacitor 216 is charged up toward Vin+Vs−VD1−VD2"; the supply voltage Vin+Vs is higher than the input voltage Vin).
Regarding claim 16, Chen discloses (see Fig. 2 and Fig. 3) a method of operating a regulator circuit (auxiliary bootstrap circuit 224 together with controller 250) for use with a circuitry, wherein the circuitry comprises a switching converter (converter 200) comprising at least a high-side switching device (high-side N-type MOSFET 202) and a low-side switching device (low-side N-type MOSFET 204) coupled in series between an input node (input node 208) at an input voltage (Vin) and a reference node (ground), and further comprises a bootstrap capacitor (bootstrap capacitor 216) coupled to the high-side switching device for supplying a drive voltage for operating the high-side switching device, wherein the method comprises: regulating charging of the bootstrap capacitor during a time period when the high-side switching device is turned on (see [0022] "the second operating mode is when the high-side switching MOSFET is ON and the low-side switching MOSFET is OFF"; further see Fig. 3 step 304: “activate auxiliary bootstrap circuit”), so as to compensate for a voltage drop across the bootstrap capacitor resulting from the high-side switching device being turned on (see [0038] "while powering driver circuit 110, bootstrap capacitor 116 discharges and voltage across capacitor 116 drops").
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.
Claim 7 is rejected under 35 U.S.C. 103 as being unpatentable over Chen in view of Fowler et al. (US Patent Application Publication US 2005/0057239 A1, hereinafter “Fowler”).
Regarding claim 7, Chen discloses (see Fig. 2) that the regulator circuit comprises a controller (controller 250) configured to monitor a voltage across the bootstrap capacitor and compare it with a predetermined threshold voltage to determine whether to activate the auxiliary bootstrap circuit (see [0050] "controller 250 additionally monitors the voltage across bootstrap capacitor 216 … When controller 250 detects that the bootstrap capacitor voltage is less than the predetermined threshold voltage, controller 250 determines that refresh is needed").
Chen does not disclose that the regulator circuit comprises a comparator module configured to take a voltage across the bootstrap capacitor and a reference voltage as inputs and generate a comparator output.
However, Fowler teaches (see Fig. 1) wherein a regulator circuit comprises a comparator module (comparator 18) configured to take a voltage across the bootstrap capacitor (Cboot) and a reference voltage (Vref) as inputs and generate a comparator output (output signal on line 20) (see [0011] "comparator 18 is coupled to and senses the voltage across the bootstrap capacitor, identified as Cboot. Comparator 18 compares this voltage across the bootstrap capacitor to a voltage reference provided thereto, and provides an output signal on line 20 which is indicative of whether the voltage of the Cboot capacitor has fallen below the voltage reference").
Therefore, it would have been obvious to one having ordinary skill in the art before the effective filing date of the claimed invention to modify the regulator circuit of Chen to comprise a comparator module configured to take a voltage across the bootstrap capacitor and a reference voltage as inputs and generate a comparator output, as taught by Fowler, because it can help provide a simple analog implementation of the bootstrap voltage threshold detection function (see [0050] of Chen "controller 250 additionally monitors the voltage across bootstrap capacitor 216"), thereby ensuring effective recharge of the bootstrap capacitor when its voltage falls below the reference (see [0005] of Fowler "a controller circuit including the comparator responsively enables a low side device to facilitate the recharging of the bootstrap capacitor when it is determined the voltage across the bootstrap capacitor is dropping or is becoming insufficient for suitable operation".
Allowable Subject Matter
Claims 3-6, 8-15 are objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. The following is a statement of reasons for the indication of allowable subject matter: Regarding claim 3, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit comprises a further switching device coupled between the supply voltage and the bootstrap capacitor; and the further switching device is controlled to be turned on or off based on the generated control pulse”. Regarding claim 4, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit is configured to adjust the pulse duration based on a reference voltage”. Regarding claim 5, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit is configured to adjust the pulse duration based on a voltage across the bootstrap capacitor when the high-side switching device is turned on”. Regarding claim 6, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit is configured to adjust the pulse duration to further compensate for process and/or temperature variations”. Regarding claim 8, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit further comprises a latch module configured to latch the comparator output when the low-side switching device is turned off”. Regarding claim 9, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit further comprises an offset compensating module coupled between the reference voltage and the respective input of the comparator module, the offset compensating module being configured to compensate for a voltage drop across the low-side switching device when the low-side switching device is turned on”.
Regarding claim 10, none of the cited prior art alone or in combination disclose or teach the claimed invention in which “the regulator circuit further comprises a bidirectional synchronous counter module configured to count up or down in accordance with the comparator output”.
Claims 11-15 are objected to due to their dependency on claim 10.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure. US 7741901 B2 discloses a charging circuit for a bootstrap capacitor. US 6201717 B1 discloses a charge-pump charging circuit for a bootstrap capacitor.
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/JYE-JUNE LEE/Examiner, Art Unit 2838
/JEFFREY A GBLENDE/Primary Examiner, Art Unit 2838
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