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Patent Issued for Voltage Regulator Having Soft Starting Function and Method of Controlling the Same

September 10, 2014



By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent by the inventor Zhu, Haigang (Suzhou, CN), filed on October 25, 2011, was published online on August 26, 2014, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 8816655 is assigned to Samsung Electronics Co., Ltd. (Suwon-Si, Gyeonggi-Do, KR).

The following quote was obtained by the news editors from the background information supplied by the inventors: "The present disclosure relates to a voltage regulator, and more particularly, to a voltage regulator including a soft start circuit.

"Most electronic devices such as computer, televisions, portable devices, and the like, include voltage regulators to supply a stable direct current. In particular, as semiconductor devices become smaller, low voltage regulators that supply low voltages from several volts to several tens of volts have been used. Low dropout (LDO) voltage regulators have been used to supply regulated voltages from power sources. Such LDO voltage regulators can operate with a very small input-output differential voltage and can provide a lower minimum operating voltage, higher efficiency operation and lower heat dissipation. However, a need exists for voltage regulators that can prevent damage to a power source resulting from inrush current."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventor's summary information for this patent: "In accordance with an exemplary embodiment of the inventive concept a voltage regulator configured to perform a soft starting operation without an additional current consumption is provided.

"Exemplary embodiment of the inventive concept also provide voltage regulator circuits configured to restrict an excessive flow of an inrush current.

"According to an exemplary embodiment, a voltage regulator apparatus includes a first power transistor and a second power transistor connected in parallel to each other between a first power source and an output terminal, and a control unit configured to turn on the first power transistor and the second power transistor. An aspect ratio of the first power transistor is smaller than an aspect ratio of the second power transistor. The control unit is configured to turn on the second power transistor in a predetermined period of time after the first power transistor is turned on.

"The aspect ratio of the first power transistor may be determined such that a maximum current flowing through the first power transistor is smaller than a rated current of the first power source.

"The aspect ratio of the first power transistor and an aspect ratio of the second power transistor may be determined such that a maximum value of a current sum flowing through the first power transistor and the second power transistor is equal to the rated current of the first power source.

"The voltage regulator apparatus may further include an amplifier connected to the first power transistor and to the second power transistor and configured to control the first power transistor and the second power transistor based upon a comparison between a feedback voltage corresponding to a voltage of an output terminal and a reference voltage. The first power transistor and the second power transistor may be controlled by the amplifier and output voltages of predetermined levels at the output terminal.

"The predetermined period of time may be longer than or equal to a time when a voltage of the output terminal of the voltage regulator apparatus is the same as a predetermined output voltage.

"The enable signal may be supplied from the first power source.

"The voltage regulator apparatus may further include a first switching unit configured to turn on the first power transistor in response to the enable signal and a second switching unit configured to turn off the second power transistor simultaneously with the first switching unit in response to a delayed enable signal.

"According to an exemplary embodiment, a voltage regulator circuit includes a first power transistor comprising a first electrode connected to a first power source and a second electrode connected to an output terminal, a second power transistor comprising a third electrode connected to the first power source and a fourth electrode connected to the output terminal, and a controller. An aspect ratio of the first power transistor is smaller than an aspect ratio of the second power transistor. The controller is connected to a control electrode of the first power transistor and a control electrode of the second power transistor. The controller is configured to sequentially turn on the first power transistor and the second power transistor in response to a received enable signal. If the enable signal is received, the controller is configured to turn on the first power transistor such that the first power source supplies power to the output terminal through the first power transistor. After a predetermined period of time after the first power transistor is turned on, the controller is configured to turn on the second power transistor such that the first power source supplies the power to the output terminal through the first power transistor and the second power transistor.

"The aspect ratio of the first power transistor may be determined such that a maximum current flowing through the first power transistor is smaller than a rated current of the first power source.

"The aspect ratio of the first power transistor and an aspect ratio of the second power transistor may be determined such that a maximum value of a current sum flowing through the first power transistor and the second power transistor is equal to the rated current of the first power source.

"The voltage regulator circuit may further include an error amplifier comprising a non-inversion input terminal, an inversion input terminal, and a signal output terminal, a feedback resistance network connected to the output terminal and the second power source, a reference voltage source configured to supply a reference voltage to the inversion input terminal of the error amplifier, a first driving buffer connected between the signal output terminal of the error amplifier and the control electrode of the first power transistor, and a second driving buffer connected between the signal output terminal of the error amplifier and the control electrode of the second power transistor. The feedback resistance network is configured to generate a feedback signal corresponding to an output voltage of the voltage regulator circuit, and to supply the feedback signal to the non-inversion input terminal of the error amplifier. The error amplifier is configured to control the first power transistor and the second power transistor based upon a comparison between a voltage level of the feedback signal and a level of the reference voltage such that the voltage regulator circuit outputs a predetermined voltage determined by the reference voltage and the feedback resistance network.

"The controller may include a start trigger. If the controller receives the enable signal, the controller may be configured to supply the enable signal to the error amplifier, to the reference voltage source, and to the first driving buffer to operate the error amplifier, the reference voltage source, and the first driving buffer. If the start trigger receives the enable signal, the start trigger may delay the enable signal during the predetermined period of time and may supply the delayed enable signal to the second driving buffer to operate the second driving buffer.

"The voltage regulator circuit may further include a first switching unit comprising a control electrode connected to the controller, a first electrode connected to the first power source, and a second electrode connected to the control electrode of the first power transistor; and a second switching unit comprising the control electrode connected to the controller, the first electrode connected to the first power source, and a second electrode connected to the control electrode of the second power transistor. The first switching unit may be configured to turn on in response to a signal supplied from the controller and turns off the first power transistor. The second switching unit may be configured to turn on in response to a signal supplied from the controller and to turn off the second power transistor simultaneously with the first power transistor.

"According to an exemplary embodiment a voltage regulator includes a control circuit configured to provide an enable signal and a delayed enable signal, and a switching circuit coupled to the control circuit and configured to generate a first driving current from a power source through a first power transistor to an output terminal in response to the enable signal and to generate a second driving current from the power source through a second power transistor to the output terminal in response to the delayed enable signal.

"The control circuit may be configured to turn on the second power transistor after a predetermined time from when the first power transistor is turned on such that a desired intensity of power from the power source is supplied to an external circuit connected to the output terminal through both the first power transistor and the second power transistor.

"The first power transistor and the second power transistor may p-type metal oxide semiconductor transistors and may be connected in parallel to each other between the power source and the output terminal.

"An aspect ratio of the first power transistor may be configured to limit an intensity of the first driving current such that the power source is not damaged by an inrush current.

"The second power transistor may have an aspect ratio higher than the aspect ratio of the first power transistor."

URL and more information on this patent, see: Zhu, Haigang. Voltage Regulator Having Soft Starting Function and Method of Controlling the Same. U.S. Patent Number 8816655, filed October 25, 2011, and published online on August 26, 2014. Patent URL: http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=8816655.PN.&OS=PN/8816655RS=PN/8816655

Keywords for this news article include: Electronics, Samsung Electronics Co., Samsung Electronics Co. Ltd., Semiconductor.

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Source: Electronics Newsweekly


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