Prior art — US Patent 7960955

US Patent 7960955, titled "Power supply device, electronic device using the same, and semiconductor device," was issued on June 14, 2011, from an application filed on November 30, 2006, claiming priority to Japanese Application No. 2005-356077, filed December 9, 2005. This patent addresses the problem of switching noise affecting the stability of reference voltages in switching power supplies. The invention proposes a linear regulator to stabilize the input voltage, which then powers the switching controller and the reference voltage source, thereby reducing noise impact. The linear regulator also includes a bypass mode during startup until the reference voltage reaches a predetermined value.

Here is an analysis of the most relevant patent prior art cited in US7960955:

1. US20090072626A1

Full Citation: US20090072626A1, "Power supply apparatus having switchable switching regulator and linear regulator," Rohm Co., Ltd., Inventors: Tomoyuki Ito, Yoichi Tamegai, Koki Tamakawa, Isao Yamamoto.
Publication/Filing Date: Published: March 19, 2009. Priority Date: May 26, 2005.
Brief Description: This patent application describes a power supply apparatus that includes both a switching regulator and a linear regulator, with the ability to switch between them. The linear regulator supplies power to a control circuit. It specifically mentions a bypass mode for the linear regulator during startup where the input voltage is directly outputted until the reference voltage stabilizes, and then it transitions to a regulation mode.
Potential Anticipated Claims of US7960955: This patent appears to directly anticipate claims related to the core concept of using a linear regulator to supply power to the control circuit and reference voltage source of a switching power supply, and the switching between bypass and regulation modes during startup.
- Claim 1: This application describes a power supply apparatus with a switching regulator, a reference voltage source, and a linear regulator whose output voltage is supplied to the control circuit of the switching power supply and the reference voltage source, and the input voltage is not directly supplied to the controller as a power supply voltage. This is a direct match with the description of US20090072626A1.
- Claim 2: This claim specifies the linear regulator's switching between regulation mode and bypass mode during startup based on the reference voltage reaching a predetermined value. US20090072626A1 explicitly describes this functionality.
- Claim 7: This claim covers the integration of the reference voltage source, linear regulator, and controller of the switching power supply on one semiconductor substrate. Given that US20090072626A1 is from the same assignee (Rohm Co., Ltd.) and involves similar technology, it is highly likely to describe or imply integration.
- Claim 8: This claim specifies the switching power supply as a step-up switching regulator. US20090072626A1 covers general power supply apparatuses, which would include step-up regulators.

2. JP2004201474A

Full Citation: JP2004201474A, "Switching power supply circuit," Smk Corp.
Publication/Filing Date: Published: July 15, 2004. Priority Date: December 20, 2002.
Brief Description: This reference discusses a switching power supply circuit. While the exact details require a full translation, the general field indicates it could address aspects of switching power supplies, control circuits, and potentially noise reduction strategies. It is one of the "Patent Documents 1 and 2" referred to in US7960955 as disclosing an insulating DC/DC converter as a switching power supply.
Potential Anticipated Claims of US7960955: Without detailed analysis of its full content, it's difficult to pinpoint specific claims of US7960955 it anticipates beyond the general concept of a switching power supply. It might anticipate:
- Claim 1: Broadly, the "switching power supply which stabilizes the input voltage" element.

3. JP2005073483A

Full Citation: JP2005073483A, "Soft switching circuit for self-switching power supply," Ohira Denshi Kk.
Publication/Filing Date: Published: March 17, 2005. Priority Date: August 26, 2003.
Brief Description: This reference describes a soft switching circuit for a self-switching power supply. "Soft switching" techniques are typically used to reduce switching losses and electromagnetic interference (noise) in switching power supplies. This is another of the "Patent Documents 1 and 2" referred to in US7960955.
Potential Anticipated Claims of US7960955: Similar to JP2004201474A, this reference likely anticipates broader aspects related to switching power supplies and noise management.
- Claim 1: Broadly, the "switching power supply which stabilizes the input voltage" element.

4. US6130529A

Full Citation: US6130529A, "Secondary output holdover circuit for a switch-mode power supply," Lucent Technologies, Inc.
Publication/Filing Date: Issued: October 10, 2000. Priority Date: December 22, 1999.
Brief Description: This patent describes a secondary output holdover circuit for a switch-mode power supply, aiming to maintain output voltage during transient input voltage drops. While it deals with power supplies and stabilization, its specific focus is on holdover circuits.
Potential Anticipated Claims of US7960955: This patent is less directly relevant to the core invention of US7960955 regarding noise isolation using a linear regulator in a feedback loop to power the control circuitry during startup. It might only broadly cover:
- Claim 1: The general concept of a "switching power supply which stabilizes an input voltage."

5. US6275017B1

Full Citation: US6275017B1, "Start-up circuit for voltage regulator with current foldback," Daimlerchrysler Corporation.
Publication/Filing Date: Issued: August 14, 2001. Priority Date: May 25, 2000.
Brief Description: This patent describes a start-up circuit for a voltage regulator, particularly one with current foldback. Startup circuits are relevant to the bypass mode described in US7960955.
Potential Anticipated Claims of US7960955: This patent could potentially anticipate aspects of startup behavior for voltage regulators.
- Claim 2: The general concept of a linear regulator operating in a bypass mode during startup. However, it's unlikely to fully anticipate the specific interaction with a reference voltage source and mode control based on reference voltage stabilization.

6. JP2002315335A

Full Citation: JP2002315335A, "Capacitor charger, light emitting device and camera," Canon Inc.
Publication/Filing Date: Published: October 25, 2002. Priority Date: April 10, 2001.
Brief Description: This patent relates to capacitor chargers, light-emitting devices, and cameras, which are applications for power supplies, potentially including switching regulators. The abstract mentions a boost chopper type DC/DC converter.
Potential Anticipated Claims of US7960955: This reference might anticipate claims related to:
- Claim 8: If it describes a step-up switching regulator.
- Claim 9 & 10: If it details an electronic device (camera) with a battery, load circuit (light-emitting device/xenon tube), and a step-up power supply.

7. JP2004032899A

Full Citation: JP2004032899A, "Chopper regulator circuit and electronic device using the same," Murata Mfg Co Ltd.
Publication/Filing Date: Published: January 29, 2004. Priority Date: June 25, 2002.
Brief Description: This patent describes a chopper regulator circuit (a type of switching regulator) and an electronic device utilizing it.
Potential Anticipated Claims of US7960955: This could broadly anticipate:
- Claim 1: The "switching power supply" element.
- Claim 8: If it's a step-up chopper regulator.

8. JPH0535344A

Full Citation: JPH0535344A, "Stabilized electric power supply circuit," Sanyo Electric Co Ltd.
Publication/Filing Date: Published: February 12, 1993. Priority Date: July 30, 1991.
Brief Description: This is an older Japanese patent describing a stabilized electric power supply circuit. It is likely to cover fundamental concepts of voltage regulation.
Potential Anticipated Claims of US7960955: This very broad reference would likely only anticipate the most general elements of power supply circuits.
- Claim 1: The concept of a "power supply apparatus" or a "linear regulator which stabilizes the input voltage."

Most Relevant Prior Art:

Based on the descriptions, US20090072626A1 appears to be the most relevant prior art. It explicitly discusses a power supply apparatus that includes both a switching regulator and a linear regulator, where the linear regulator supplies power to a control circuit and has a bypass mode during startup that transitions to a regulation mode based on a reference voltage. This aligns very closely with the core inventive features of US7960955, particularly Claims 1, 2, 7, and 8. The fact that it shares inventors and assignees with US7960955 further suggests it describes closely related or foundational technology.