An electronic circuit includes a noise source and an analog circuit and a logic circuit that may be adversely affected by noise. At least a portion of the analog circuit and the logic circuit is formed on a buried impurity layer whose conductivity is different from that of a substrate, and at least a portion of the periphery of that portion is surrounded by an impurity layer that is different from the substrate. Thus, propagation of the noise from the noise source is prevented.

An overvoltage protection apparatus and method. The overvoltage protection apparatus includes: a determining unit, having an input end connected to an input end of the apparatus and an output end connected to an input end of a soft-start unit, and configured to determine whether an input voltage at the input end of the apparatus exceeds a preset protection voltage; and the soft-start unit, having an input end connected to the input end of the apparatus and an output end connected to an output end of the apparatus, where if the determining unit determines that the input voltage does not exceed the preset protection voltage and remains stable in a preset delay time, the soft-start unit delivers the input voltage to the output end of the apparatus; and otherwise, the soft-start unit does not deliver a voltage signal to the output end of the apparatus.

A power supply device includes an output circuit configured to be supplied with electric power from a power supply, and to output a current, a driving circuit configured to control an output operation of the output circuit to output a current, an overcurrent detection circuit configured to output a detection signal to a first node when detecting an overcurrent in the output circuit, an off-state fixing circuit configured to output an off-state fixing signal to the driving circuit for performing a forcible suspension of the output operation of the output circuit based on a detection signal inputted to the first node, regardless of whether a control signal is outputted, and a control unit configured to receive the detection signal and to output the control signal for controlling the output operation to the driving circuit in order to cause the driving circuit to control the output operation.

An overvoltage protection apparatus and method. The overvoltage protection apparatus includes: a determining unit, having an input end connected to an input end of the apparatus and an output end connected to an input end of a soft-start unit, and configured to determine whether an input voltage at the input end of the apparatus exceeds a preset protection voltage; and the soft-start unit, having an input end connected to the input end of the apparatus and an output end connected to an output end of the apparatus, where if the determining unit determines that the input voltage does not exceed the preset protection voltage and remains stable in a preset delay time, the soft-start unit delivers the input voltage to the output end of the apparatus; and otherwise, the soft-start unit does not deliver a voltage signal to the output end of the apparatus.

In accordance with an embodiment, a method of controlling a switch driver includes energizing a first inductor in a first direction with a first energy; transferring the first energy from the first inductor to a second inductor, wherein the second inductor is coupled between a second switch-driving terminal of the switch driver and a second internal node, and the second inductor is magnetically coupled to the first inductor; asserting a first turn-on signal at the second switch-driving terminal using the transferred first energy; energizing the first inductor in a second direction opposite the first direction with a second energy after asserting the first turn-on signal at the second switch-driving terminal; transferring the second energy from the first inductor to the second inductor; and asserting a first turn-off signal at the second switch-driving terminal using the transferred second energy.

A power supply device includes an output circuit configured to be supplied with electric power from a power supply, and to output a current, a driving circuit configured to control an output operation of the output circuit to output a current, an overcurrent detection circuit configured to output a detection signal to a first node when detecting an overcurrent in the output circuit, an off-state fixing circuit configured to output an off-state fixing signal to the driving circuit for performing a forcible suspension of the output operation of the output circuit based on a detection signal inputted to the first node, regardless of whether a control signal is outputted, and a control unit configured to receive the detection signal and to output the control signal for controlling the output operation to the driving circuit in order to cause the driving circuit to control the output operation.

A power conversion device includes a first switch and a second switch connected in series between a positive electrode and a negative electrode of a first power supply. A first node is between the first and second switches. The first node can be connected to a load. A first diode has an anode connected to the first node and a cathode connected to the positive electrode of the first power supply. A third switch is connected between a positive electrode of a second power supply and the positive electrode of the first power supply. A first timer is connected to a gate electrode of the third switch. A first comparator has a first input that is connected to a gate electrode of the first switch, a second input at which a reference voltage can be received, and an output that is connected to the first timer.

A lens driver or lens driver circuitry for an ophthalmic apparatus comprising an electronic system which actuates a variable-focus optic is disclosed herein. The lens driver is part of an electronic system incorporated into the ophthalmic apparatus. The electronic system includes one or more batteries or other power sources, power management circuitry, one or more sensors, clock generation circuitry, control algorithms and circuitry, and lens driver circuitry. The lens driver circuitry includes one or more power sources, one or more high voltage generators and one or more switching circuits. Specifically, the lens driver comprises an H-bridge/H-bridge controller for providing the proper voltage, including polarity, to drive the electronic included in the ophthalmic apparatus.

Disclosed is an electronic circuit for controlling a half H bridge, the half split H bridge including first and second MOSFET transistors of different respective types, with sources connected respectively to a supply line and to an electric mass, and with respective drains connected to a load. Moreover, the control circuit includes first and second bipolar transistors of different respective types, with collectors connected to the supply line and to the electric mass, respectively, and with respective bases connected to a control module for controlling the MOSFET transistors, as well as first and second arms mounted parallel relative to one another between the gates of the MOSFET transistors, connected to the emitter of the first bipolar transistor and of the second bipolar transistor, respectively, the first arm including a first diode and a first resistor, and the second arm including a second diode and a second resistor.

A high side transistor is coupled between a high potential side power source node and an intermediate node, and a recirculation diode is coupled between a low potential side power source node and the intermediate node, thereby forming a recirculation path when the high side transistor is OFF. A power source supply line couples the high potential side power source node with one end of the high side transistor. A surge recirculation device causes a current to flow in one direction, and a surge recirculation line couples the one end of the high side transistor to the high potential side power source node through the surge recirculation device, and causes a surge generated at the one end of the high side transistor to recirculate toward the high potential side power source node.