137 results about "Low-voltage detect" patented technology

An LED driving circuit driving an LED array includes: n constant-current driving elements having a vertical structure, each of which is connected to each of LED strings in series and drives the LED string with a constant current; n constant-current control circuits controlling on voltages of the constant-current driving elements so that currents flowing to the LED strings become constant currents; a lowest-voltage detecting circuit to which terminal voltages of the constant-current driving elements on an LED string side are inputted, the lowest-voltage detecting circuit selecting a lowest voltage from among the terminal voltages and outputting a command signal based on difference between the lowest voltage and a predetermined set voltage; and a power-supply control circuit controlling a voltage applied to the LED array to a voltage lower than an initial set voltage based on the command signal.

In a load drive circuit, a charge pump circuit inputs a battery voltage of a power line, and outputs a raising voltage proportional to the battery voltage. A low voltage detecting circuit detects a low voltage state in which a detecting voltage obtained by dividing the raising voltage is lower than a reference voltage. Thus, it is possible to indirectly detect a low voltage state in which the battery voltage is lower than a predetermined threshold value. When the low voltage state is detected, a drive circuit turns off a MOSFET. At this time, the battery voltage is temporarily varied, but the charge pump circuit has a filter action and a delay action, whereby temporary variation does not easily appear in the raising voltage (detecting voltage), and an error in operation of the MOSFET can be prevented.

A low voltage detect circuit is provided herein for detecting when an external voltage (Vext) drops below a predetermined minimum voltage. In general, the low voltage detect circuit described herein may be configured to detect a low voltage condition based on a threshold voltage difference between a non-zero threshold transistor having a substantially non-zero threshold voltage, and a zero threshold transistor having a threshold voltage relatively close to zero. According to a particularly advantageous aspect of the invention, the low voltage detect circuit described herein comprises substantially no resistors or reference voltage generation circuits, and therefore, provides significant savings in both current and die area consumption without sacrificing accuracy. The low voltage detect circuit of the present invention is particularly useful in power regulators, such as those used in memory systems or devices.

The object of the present invention is to provide a bi-directional DC-DC converter having a simplified circuit configuration. Each output of high voltage detection circuit (12) and low voltage detection circuit (15) is inputted to high-voltage side error amplifier circuit (50) and low-voltage side error amplifier circuit (51) independently disposed, which are configured so as to be inverse in polarity, and the output of high-voltage side error amplifier circuit (50) or the output of low-voltage side error amplifier circuit (51) is selected by converting direction switching circuit (22), and the output is inputted to control circuit (25) from PWM comparison circuit (21) being in common with respect to voltage step-up and decreasing operations, thereby driving the first switching element (5) and the second switching element (10). Thus, a inverting circuit conventionally used is not needed, and in addition, only one 3-terminal switch usually complicated in structure is used, and it possible to realize a bi-directional DC-DC converter having a simple configuration as a whole.

The present invention discloses a circuit and a method of adjusting system clock in low voltage detection, and a low voltage reset circuit. The circuit of adjusting system clock in low voltage detection comprises: a clock generator for supplying a clock to at least one circuit in a system; and a low voltage reset circuit for generating an adjustment signal according to a detected voltage level, so that the clock generator adjusts or stops the clock supplied to the at least one circuit in the system.

The invention discloses data power down protection technology based on non-volatile storage portable set. The portable set is set capacitance and low voltage detecting module to do low voltage detecting before data read-in and erasing for the non-volatile storage structure; if the voltage is abnormal, any operation doesn't be executed; if the portable set is power down while data read-in and erasing, capacitance discharges to supply required voltage to make the system finish oncoming operation. The invention can avoid bad data when the non-volatile storage is suddenly power down, can save firmware program development time and firmware code storage space, has higher data stored reliability and security compared with the existing method.

A low voltage detector (100) includes a power supply voltage monitor circuit (110) that produces a voltage VSP related to a first a power supply voltage, and a voltage generator (105), which includes a plurality of self-cascode MOSFET (SCM) structures (101-103) in a cascade configuration, that generates a reference voltage Vxm. A voltage comparator (140) outputs an output signal in response to a differential between Vxm and VSP, wherein Vxm and VSP have proportional to absolute temperature behavior (PTAT) over temperature with respect to a second power supply voltage. The output signal changes state when the first power supply voltage equals a trip point of the comparator. Each SCM structure is sized to provide a rate of change with temperature of the PTAT behavior of Vxm that matches a rate of change with temperature of the PTAT behavior of VSP.

Provided is a microcontroller including: a first low-voltage detection circuit to detect that a power supply voltage is equal to or lower than a first voltage value; a second low-voltage detection circuit to detect that the power supply voltage is equal to or lower than a second voltage value, the second voltage value being lower than the first voltage value; a CPU to stop operating when the first low-voltage detection circuit detects that the power supply voltage is equal to or lower than the first voltage value; and a real-time clock to continue operating unless the second low-voltage detection circuit detects that the power supply voltage is equal to or lower than the second voltage value, in which the first low-voltage detection circuit, the second low-voltage detection circuit, the CPU, and the real-time clock are formed on a single chip.

The invention relates to a phase-lack and low-voltage detection circuit for three-phase alternating current, and belongs to the technical field of power electronic products. The phase-lack and low-voltage detection circuit comprises three groups of phase detection circuits and a comparison output circuit, wherein the three groups of phase detection circuits are connected in parallel; the input end of each group of phase detection circuits is respectively connected with a phase alternating current input end of the three-phase alternating current in a power grid to be detected for respectively detecting phase-lack and low-voltage of the phase alternating current input; output ends of the three groups of phase detection circuits are connected with the input end of the comparison output circuit after being connected mutually, and a detection result is output by the comparison output circuit; each group of phase detection circuits comprises a rectifying circuit, a current-limiting circuit, an amplitude-limiting circuit, an opto-coupling isolating circuit, a charging and discharging circuit and an isolating circuit which are connected in sequence, wherein the input end of the rectifying circuit and the other input end of the opto-coupling isolating circuit are respectively connected with both ends of each phase alternating current. The phase-lack and low-voltage detection circuit has the characteristics that a two-in-one function of phase-lack detection and input low-voltage detection is realized, the circuits are simple, power consumption is very little, SMT (Surface Mounted Technology) can be realized and embedded in equipment, and the like.

The invention discloses an alternating current excitation insulation detection circuit which comprises anode insulation resistance Rz and cathode insulation resistance Rf from a total positive end and a total negative end of a power supply battery set to an electrocar body, and further comprises an alternating current signal source, a sampling module and a data processing module which are used for detecting the insulation resistance value between the electrocar body and the power supply battery set so as to determine the insulation state of the electrocar. Compared with the prior art, the alternating current excitation insulation detection circuit has the advantages that low-voltage detection is adopted, signals cannot be disturbed easily, accuracy of detection of the insulation resistance value is improved, and the circuit is relatively simple and easy to produce and use.

An Ultra-low power voltage detection circuit is implemented in a digital integrated circuit to device to provide a basic timer, programmable timer and programmable low voltage detection (PLVD) using a single connection of the digital integrated circuit device and a passive component(s) external to the digital integrated circuit device. An internal low current source may be enabled so as to discharge an external timing capacitor connected to the output connection, thus eliminating the need for an external resistor. However, timing accuracy may be improved by adding an external discharging resistor and / or charging resistor. The output connection may be configured as a tri-state output and may be driven high to charge and low to discharge the timing capacitor. A voltage reference may be used in determining a voltage trip point for timing and low voltage detection purposes. Temperature may be determined from either a trip voltage compared to a known voltage determined at a known temperature, or a current value of the current source compared to a known current value determined at a known temperature, times a constant.

A circuit for adaptively adjusting the drive strength of output power transistors in a class D amplifier is provided. The circuit includes a driver circuit and a low-voltage detect circuit. The low-voltage detect circuit is arranged to assert a low-voltage detect signal if a low supply voltage condition is detected. The driver circuit is arranged to increase the drive strength if the low-voltage detect signal is asserted. The driver circuit includes a first driver and a second driver. The second driver is enabled if the low-voltage detect signal is asserted, and disabled if the low-voltage detect signal is unasserted.

A low voltage detector and method of detecting low voltage of a nonvolatile memory chip is disclosed wherein a memory cell does not operate in a low voltage and definitly discriminate activation and deactivation voltage area of the chip by synchronizing operation start and stop points of a FeRAM cell to a chip enable signal according to variation of system power for safely operating the chip in threshold voltage region. In this way, because the chip safely operates even the threshold voltage region such as the on / off states of power voltage, the chip can be protected even at the on / off states of power voltage and the layout area of the chip becomes efficient without having additional circuits.

The invention discloses a low-voltage reset method used in a microcontroller. A low-voltage reset circuit of the low-voltage reset method comprises a low-voltage detection circuit which is controlled by a sleep signal of a system, and also comprises an anti-interference management circuit which utilizes a clock signal in a microcontroller circuit for filtering and generates a reset signal, wherein an output signal of the low-voltage detection circuit and the clock signal are input signals of the anti-interference management circuit together. The low-voltage reset method guarantees that the reset circuit has the characteristics of low power consumption, high precision, anti-interference and so on, so that the microcontroller product can be operated in a situation with low power consumption and realize good electrifying property.

An intelligent fuel gas oven controlled by computer cosists of a fuel gas oven, pot support frame on the oven, ignition device set at front end of pot support frame near the oven, control panel board set at front end of face panel for the oven with its surface to be set with control keyboard, indicator and remote control of receiving inductor and its internal to be set with computer control system, also temperature sensing probe and gas leakage inductor to be set on the face panel of the oven. The principle circuit of intelligent fuel gas oven uses single chip computer of IC1 as a core controller together to connect with the following functional parts of keyboard circuit, temperature measuring, voice, gas leakage detecting, low voltage detection for ignition, infrared remote control receiving, output control, indication, no pot detection, infrared emission part to be extended, serial interface and power supply.

A circuit for prevention of unintentional writing to a memory prevents unintentional writing to a nonvolatile memory, after a recovery from a transitory power failure. The circuit includes a low-voltage detection circuit for detecting a power supply voltage drop depending on the state of a control signal for the detection circuit. A writing operation to the memory is prohibited depending on the control signal as well as upon an output signal of the low-voltage detection circuit.

In a pressure sensor with double measuring scale: a monolithic body of semiconductor material has a first main surface, a bulk region and a sensitive portion upon which pressure acts; a cavity is formed in the monolithic body and is separated from the first main surface by a membrane, which is flexible and deformable as a function of the pressure, and is arranged inside the sensitive portion and is surrounded by the bulk region; a low-pressure detecting element of the piezoresistive type, sensitive to first values of pressure, is integrated in the membrane and has a variable resistance as a function of the deformation of the membrane; in addition, a high-pressure detecting element, also of a piezoresistive type, is formed in the bulk region inside the sensitive portion and has a variable resistance as a function of the pressure. The high-pressure detecting element is sensitive to second values of pressure.

A low-voltage detection circuit that is small in size and accurate in detecting a reduction in a power supply voltage is offered. The low-voltage detection circuit of an embodiment of this invention detects a low voltage using a voltage follower type operational amplifier and an A / D converter instead of a conventional low-voltage detection circuit. That is, a reference voltage Vref is applied from a reference voltage generating circuit to the A / D converter through the voltage follower type operational amplifier. The voltage follower type operational amplifier is used to reduce output impedance. The power supply voltage Vdd can be detected by a converted value (a digital value) from the A / D converter since the reference voltage Vref is independent of the power supply voltage Vdd and the converted value varies depending on the power supply voltage Vdd. The converted value (the digital value) from the A / D converter is set in a register and statuses of a microcomputer are set as in the conventional art, using the converted value as a flag.

A low-voltage detection reset circuit that suppresses a current consumption in a stand-by mode and is reduced in a size is offered. The low-voltage detection reset circuit is provided with a power-on reset circuit that operates only at power-on and outputs a reset pulse and is configured to set a detection level of a detection level setting circuit at a default value using the reset pulse and to activate a programmable low-voltage detection circuit. After the programmable low-voltage detection circuit is activated, a detection level of the programmable low-voltage detection circuit can be modified from the default value by a register.

A low voltage detector (100) includes a voltage and current reference circuit (102); a power supply voltage monitor circuit (104), coupled to the voltage and current reference circuit and to a power supply; and a voltage comparator (106), coupled to the voltage and current reference circuit and to the power supply voltage monitor circuit. The voltage and current reference circuit includes a self-cascode MOSFET structure (SCM) (110) that produces a reference voltage. The power supply voltage monitoring circuit includes another SCM (140) that produces a monitor voltage, related to the power supply voltage. The reference voltage and the monitor voltage have a same behavior with changes in temperature, thereby allowing the trip point of the low voltage detector to minimally vary with temperature. The low voltage detector is disposed on an integrated circuit (101), and the transistors of the low voltage detector consist of only CMOS transistors.

The invention discloses a battery car low-voltage detection and alarm circuit. The battery car low-voltage detection and alarm circuit comprises a storage battery voltage output end, a detection circuit and an alarm circuit. When the detection circuit detects that a storage battery voltage decreases to an alarm value and the negative input end of a comparator is lower than a triode threshold voltage, the comparator outputs high level, a MOS tube is conducted, an LED lamp emits light and brightens, and power amplifier alarm is realized, then it can be acknowledged that the storage battery voltage is at a low voltage state such that the purpose of the invention is realized. The invention relates to the battery car low-voltage detection and alarm circuit, the detection method is simple, and people can be prompted to charge a battery car during use so as to reduce unnecessary trouble.

The invention relates to a magnetic brake controller, which comprises a current limiting circuit (1), a low voltage checking circuit (2), a starting circuit (3), a full-wave rectification circuit (4), a subsequent flow attenuation circuit (5), a high voltage checking circuit (6) and a power supply on-off fast reaction circuit (7). The invention uses a capacitor to limit current so that the consumption and the fault rate are almost zero. A fast attenuation induction subsequent flow link is set so that the demagnetization of an electromagnet is quick and the brake of a brake is fast. The invention has no electromagnetic interference, does not cause higher harmonics pollution on a power supply and can work when UPS is used for supplying power.

The invention discloses a reset circuit based on a low-voltage detection function. The reset circuit with simple structure and low power consumption comprises a voltage detection module, a reset output module, a voltage amplification module, a voltage shaping A module, and a voltage shaping B module, wherein the voltage detection module is used for forming a threshold voltage value which is needed by the reset circuit to generate a reset signal, and determining the working state of the reset circuit in the voltage electrifying or power down process of a VDD (Virtual Device Driver) power supply according to the threshold voltage value; the reset output module is used for outputting a low level to serve as a reset signal when the reset circuit is in an unnormal work state, and outputting a high level when the reset circuit is in a normal work state; the voltage amplification module is used for outputting a low level to serve as a memorizer lock enable signal when the reset circuit is inan unnormal work state, and outputting a high level to serve as a memorizer enable signal when the reset circuit is in a normal work state; the voltage shaping A module is used for shaping the outputvoltage of the reset output module; and the voltage shaping B module is used for shaping the output voltage of the voltage amplification module.

The present invention relates to a low-voltage tripping mechanism of a low-voltage breaker. The tripping mechanism comprises an electromagnetic mechanism housed in front portion of a chamber of a case and an electronic module housed in rear portion of the case; the electromagnetic mechanism comprises an armature, a front yoke, a working coil, a baffle and a rear yoke, characterized in that a permanent magnet is disposed between the rear yoke and the baffle, a closed coil is disposed between the working coil and the baffle, a power storage spring is mounted in the chamber behind the armature with the spring counteracting against the baffle, the circuits of said electronic module comprises a low-voltage detecting circuit, a synthetic signal controlling circuit, a main controlling circuit and a D.C. power supply. It's advantages include such as small volume simple structure, constant holding force, the coil being not overheated in high voltage, the contacts being closed reliably in low voltage, actuating voltage being accurate, power-saving and low noise.