92 results about "Undervoltage-lockout" patented technology

A half bridge gate driving circuit for providing gate driving circuits in a bi-hecto celcius (200 degrees celcius) operating environment having multiple functions including combinations of multiple level logic inputs, noise immunity, fault protection, overlap protection, pulse modulation, high-frequency modulation with transformer based isolation, high-frequency demodulation back to pulse width modulation, deadtime generator, level shifter for high side transistor, overcurrent protection, and undervoltage lockout.

A wide input voltage power supply circuit for a load includes a first stage and a second stage. The first stage includes a linear regulator circuit configured to maintain an output voltage at a predetermined output voltage level. The linear regulator includes an input for shutting the linear regulator off when an input voltage exceeds a predetermined shut off threshold. The second stage includes a high voltage detection circuit coupled to the input of the linear regulator. The high voltage detection circuit is configured to detect the level of the input voltage and to shut the linear regulator off when the input voltage exceeds the predetermined shut off threshold. An under voltage lockout circuit may be included, the under voltage lockout circuit configured to set a minimum turn-on voltage for the load.

Exemplary embodiments of the present invention relate to an under-voltage lockout circuit, and a switching control circuit and a power supply including the same. The under-voltage lockout circuit according to an embodiment of the invention includes a first under-voltage lockout circuit comparing a driving voltage with a first reference voltage and a second under-voltage lockout circuit generating an under-voltage lockout signal based on a result of the comparison between the driving voltage and the second reference voltage. The first under-voltage lockout circuit stops operation of the second under-voltage lockout circuit when the driving voltage is lower than the first reference voltage and operates the second under-voltage lockout circuit when the driving voltage is higher than the first reference voltage. Power consumption of the first under-voltage lockout circuit is limited by a first current that generates the first reference voltage.

The invention discloses an under-voltage lockout circuit of a voltage reference self-produced. The method for forming the voltage reference to compare with a sampling voltage comprises the steps of: providing a basic current supply in a power return circuit; forming a first branch circuit and a second branch circuit which are in parallel, wherein each branch circuit comprises at least one triode which is used to form a current with a positive temperature coefficient; connecting the base electrode of a first triode with the base electrode of a second triode to output the reference voltage; providing an error amplifier for clamping which is connected astride between the first branch circuit and the second branch circuit to obtain a first node and a second node in equal potential; providing a compensation resistance which is used for the reference voltage to enable the basic current with the positive temperature coefficient outputted by the parallel branches produce a voltage drop on the compensation resistance in proportion to the temperature. Due to the temperature compensation on the voltage reference self-produced, the stability of locking a threshold voltage and a lag is ensured.

A control circuit for a DC-DC converter that prevents a deficiency from occurring due to sudden interruption in power supply. The control circuit activates and inactivates a main switching output transistor and a synchronous rectification output transistor to convert the input voltage to an output voltage. The output voltage is smoothed by a smoothing capacitor. When the input voltage decreases, the control circuit activates the synchronous rectification output transistor to readily discharge the smoothing capacitor via the synchronous rectification output transistor.

A switching power supply system controlling switching operations of switching devices by a control circuit to convert an input voltage into a desired output voltage, the system being provided with a under voltage lock out circuit including: an input voltage detection unit detecting an input voltage and producing an input voltage digital signal corresponding to the input voltage Vin; and a voltage level comparison unit carrying out digital comparison of the input voltage digital signal with each of two voltage detection level data and outputting the results of the comparisons as an output signal, in which by changing voltage detection level data stored in two registers, desired voltage detection levels and hysteresis characteristic are easily actualized.

A start-up circuit in a switch-mode power converter that employs a Zener diode to provide a reference voltage to reduce the power consumption and the size of the start-up circuit. The start-up circuit also includes a coarse current source and a coarse reference voltage signal generator for producing current and reference voltage for initial startup operation of a bandgap circuit. The reference signal and current from coarse current source and the reference voltage signal generator are subject to large process, voltage and temperature (PVT) variations or susceptible to noise from the power supply, and hence, these signals are used temporarily during start-up and replaced with signals from higher performance components. After bandgap circuit becomes operational, the start-up receives voltage reference signal from the bandgap circuit to more accurately detect undervoltage lockout conditions.

The invention discloses a gate driving circuit with a protection function for an enhanced GaN power device. The circuit comprises an interface circuit H, an interface circuit L, a dead zone generatingcircuit, a level shifting circuit, a low-end delay matching circuit, a driving circuit H, a driving circuit L, an undervoltage lockout circuit H, an undervoltage lockout circuit L, an overcurrent protection circuit, and an overheat protection circuit. The driving circuit can automatically detect the chip overheating, undervoltage or overcurrent of voltage and power supply, and turns off the GaN power device for protection to ensure that its operating characteristics are in a safe zone.

A safety circuit for a rechargeable cell is employed as a simple, low cost, fuel gauging circuit. The safety circuit includes an undervoltage circuit having a reference voltage. The input of the safety circuit is selectively coupled between the voltage of a rechargeable cell and a scaled down voltage of the rechargeable cell. The scaled down voltage corresponds to a predetermined capacity threshold. A user or electronic device actuates a switch that couples the scaled down voltage to the safety circuit. The safety circuit compares this scaled down voltage to the reference voltage of it's under voltage circuit. If the scaled down voltage is above the reference voltage, the safety circuit causes a transistor coupled serially with the cell to be on, or in a conductive state, so as to allow current to flow through a capacity indicator like a LED. If the scaled down voltage is below the reference voltage the safety circuit causes the transistor to enter a high impedance state, thereby turning the indicator off. The state of the indicator provides the user with an approximation of the cell's remaining capacity. In a battery pack, two or more safety circuits with different reference voltages may be employed for increased resolution.

Examples of the disclosure are directed to methods of managing power of various modules of an electronic device to prevent the voltage of the battery from falling to an undervoltage lockout (UVLO) threshold. In some examples, software operating on the electronic device or an associated electronic device (e.g., a paired electronic device) may assign power budgets to one or more modules, thereby preventing each module from drawing its maximum current capacity and causing the battery's voltage level to fall to the UVLO threshold. In some examples, a pre-UVLO threshold (i.e., a threshold higher than the UVLO threshold) may be used to modify the states of one or more modules to save power as the voltage of the battery approaches the UVLO threshold, but before the device must be fully powered off.

The invention discloses a secondary startup control circuit and a switching power supply. The secondary startup control circuit comprises an under-voltage lock, a startup state register, an electrified restorer, an oscillator, a delay counter and a logic and gate. The circuit can reduce AC input power when secondary output of the switching power supply is in short circuit, enhance safety and reliability of the switching power supply, and save energy.

A switching power supply device includes a power factor correction (PFC) circuit, a DC-DC converter, and a control IC incorporating functions of controlling these components. At power up, a capacitor connected to a terminal VCC is charged with a current whose voltage has been adjusted by a starting circuit. When a voltage across the capacitor reaches a UVLO cancelation voltage, an under-voltage lockout (UVLO) circuit outputs a first enable signal, thereby driving a PFC control circuit. When the PFC control circuit outputs a PFC switching signal, a PFC switching detection circuit outputs a second enable signal, thereby driving an LLC control circuit. Since the time between the start of the PFC switching operation and the start of the operation of the LLC control circuit is shortest, there is no need to supplement the starting power and arrange an auxiliary winding for an inductor.

A voltage comparison unit compares a battery voltage with a predetermined threshold voltage, and outputs a comparison signal. A sequence circuit receives the comparison signal and a start-up signal instructing start-up of equipment mounted with a UVLO circuit, and executes a predetermined sequence when start-up is instructed by the start-up signal in a state the battery voltage is higher than the threshold voltage. A voltage control unit switches the threshold voltage based on the comparison signal and the start-up signal.

The UVLO (undervoltage lockout) circuit provides a very low quiescent current that is independent of supply voltage. The circuit includes a low voltage IPTAT (current proportional to absolute temperature) generator coupled to a comparator 24 wherein a first input of the comparator 24 is coupled to the IPTAT generator in a way that forms a bandgap voltage with respect to ground and a second input of the comparator 24 is coupled to the IPTAT generator in a way that forms a bandgap voltage with respect to a supply node. This makes the quiescent current independent of the supply voltage because there is no voltage divider between the supply node and ground.

A sleep circuit for use in a resonant inverter is disclosed. The sleep circuit activates a “sleep mode” (non-continuous operation) when the inverter output has no connected load, or a connected load is non-operative (e.g., fails). The “sleep mode” utilizes hysteresis control via the under voltage lockout protection feature of a control IC of the inverter. A primary DC source permanently connects to the Vcc pin of the control IC for startup (on) and burst (non-continuous) operation modes. An auxiliary DC source connects to the Vcc pin via a switch for continuous operation mode. A load current sensor controls the switch. When a sensed output current is above a threshold level, the switch connects the auxiliary DC source, and the control IC (and the inverter) operates continuously. When the sensed output current falls below the threshold, the auxiliary DC source is not provided and the inverter operates in “sleep mode”.

The power switch device, including a controller, an undervoltage lockout circuit (UVLO) and an input voltage detection circuit, is configured to appropriately switch either a battery power or a public electricity to a portable electrical product. The power switch device further includes a thermal sense circuit, a current detection circuit and an output voltage detection circuit to provide over-high or over-low voltage protection, over-high current protection and over-high temperature protection.

The invention discloses a controller. The controller comprises a switch tube, a first hysteresis comparator, a second hysteresis comparator, a pulse width modulation (PWM) comparator, a control signal (CS) comparator, an or gate and a logic controller, wherein the switch tube controls work of a transformer; the first hysteresis comparator compares a comparator (COMP) signal with load threshold value Vref1 and outputs a burst signal; the second hysteresis comparator compares a source voltage VCC with a power threshold value Vref2 and outputs a hold signal; a control end of the PWM comparator is connected with the burst signal, and an output end is connected with the logic controller; an output end of the CS comparator is connected with the logic controller; two input ends of the or gate are connected with the hold signal and the burst signal respectively and output a control signal (control) to the logic controller; the logic controller controls the switch tube; and when COMP is less than Vref1 and VCC is less than Vref2, the controller works in a holdup mode, the PWM comparator is shielded, the comparison level of the CS comparator is low level, and the switch tube has output and keeps the power voltage VCC over under-voltage locking voltage. The invention also discloses an adjustment and control method for the controller. The adjustment and control method has a good power-saving effect.

A synchronous rectifier control circuit improves energy conversion efficiency and uses a signal produced by a secondary winding of a transformer in a rectifier circuit to control a low-impedance and a low power consuming current switch such as a JFET and a MOSFET in a synchronous rectifier circuit to substitute a high power consuming diode rectification and appropriately rectify and extend the ON time of the current switch to prevent the positive and negative phases of the current switch to be turned on simultaneously, which will cause a large current to burn the current switch. The invention includes a protection circuit having an under voltage lock out circuit for an interrupt output function, so that if an insufficient instant power voltage occurs, the power is turned on or off to interrupt all outputs and force the current switch of the rectifier circuit to turn off, and prevent the output of an unstable working voltage of the rectifier control circuit or the abnormal operation of the current switch.

The invention provides an alternating current(AC) / direct current (DC) voltage converting circuit with low stand-by power consumption, which comprises a safety capacitor, a common mode filter inductor, a rectifier bridge, a filter and a switching power supply circuit which are connected in parallel in sequence, wherein the safety capacitor receives input power, and the input power is processed by the common mode filter inductor, the rectifier bridge and the filter and then input to the switching power supply circuit; the switching power supply circuit comprises a power stage circuit, a control circuit and a phantom load, and the control circuit is used for detecting whether the input power works normally and controls the power stage circuit to perform voltage conversion on the input power; when the input power is in a normal working state, the phantom load is removed; and when the input power is in an under-voltage locking working state, the phantom load is loaded to perform discharging on the safety capacitor. The AC / DC voltage converting circuit solves the problem of power consumption caused by the direct addition of discharge resistance in the prior art, reduces the cost of a switching tube and is favorable for circuit integration.

A system and a method are disclosed for providing a temperature compensated under-voltage-lockout circuit that has a trip point voltage that is not sensitive to temperature variation. The under-voltage-lockout circuit of the invention comprises (1) an inverter circuit that is coupled to a supply voltage and (2) a temperature compensation circuit that is coupled to the supply voltage and to the inverter circuit. The temperature compensation circuit and the inverter circuit temperature compensate a trip point voltage of the inverter circuit by driving an input of the inverter circuit with a voltage that has a same temperature coefficient as the trip point voltage of the inverter circuit.

An UVLO circuit according to an aspect of the present invention includes: a power-on reset (POR) circuit generating an output based on a first current that flows according to an increase of a power supply voltage and not operating in a normal state of the power supply voltage; and a logic operation unit generating a reset signal according to an output of the POR circuit and an output based on a result of comparison between a sense voltage that corresponds to the power supply voltage and a predetermined reference voltage.

An under voltage lockout circuit configured to set a minimum turn-on voltage for a load is provided. The circuit includes an input terminal configured to receive an input voltage. The circuit includes a first transistor configured to become conductive to supply the input voltage to the load when an input voltage to the under voltage lockout circuit exceeds a threshold, and a second transistor coupled to the first transistor, the second transistor configured to become conductive to supply the input voltage to a first resistor and not to the load when an input voltage to the under voltage lockout circuit falls below the threshold.

The invention discloses a high-power and long-distance standard POE separator comprising a POE separator components, which specifically comprise a power supply and signal separation circuit, an identification and classification circuit, a power management circuit and an LTE network extension circuit, the power supply and signal separation circuit is electrically connected with the identification and classification circuit, the identification and classification circuit is connected with the power management circuit, and the power supply and signal separation circuit is connected with the LTE network extension circuit. The product has the advantages of flexible and adjustable classification, flexible and adjustable undervoltage lockout threshold, long-distance transmission supporting, flexible and efficient power management, adjustable output voltage and power, low circuit cost and small volume and the like beside being compatible with the standard and non-standard PSE products on the market.

The invention provides an under-voltage protection device and a system of a converter control system; the device comprises a first energy accumulating unit, a second energy accumulating unit and an under-voltage protection unit; when the first energy accumulating unit is charged by an input power supply, and discharges and supplies power to a converter control unit; the second energy accumulating unit is charged by the input power supply, and discharges and supplies power to a switch tube driver; the under-voltage protection unit samples the voltage of the input power supply; and if the sampled voltage is less than first reference voltage, an under-voltage locking signal is sent to the converter control unit. We can know that when the first energy accumulating unit and the second energy accumulating unit discharge, the first energy accumulating unit supplies power to the converter control unit and the second energy accumulating unit supplies power to the switch tube driver, so that the converter control unit sends a correct blocking instruction and the switch tube driver correctly cuts off and protects an IGBT (insulated gate bipolar transistor) when the input power supply is under-voltage or loses power, and a converter safely exits a running state.

The invention relates to the field of integrated circuit design. In order to achieve the goals of monitoring power supply voltage of a PFC (power factor controller) chip and simultaneously realizing internal low-voltage source and reference circuit which are not related to temperature, the invention adopts the technical scheme that a turn-threshold-adjustable under voltage lockout (UVLO) and reference voltage circuit comprises a UVLO module and a VDD Reg module; the UVLO module outputs voltage to the VDD Reg module; when the input voltage VCC of the UVLO module is increased to VCC (on), the UVLO module outputs high-level voltage, the VDD Reg module outputs non-temperature-related internal low-voltage power VDD, reference voltage Vref, vddgd and under voltage lockout signals vddgd_b, and the under voltage lockout signals vddgd_b are low-level voltage; and when the VCC is decreased to VCC (off), the UVLO module outputs low-level voltage. The turn-threshold-adjustable UVLO and reference voltage circuit is mainly applied to integrated circuit design.

A voltage comparison unit compares a battery voltage with a predetermined threshold voltage, and outputs a comparison signal. A sequence circuit receives the comparison signal and a start-up signal instructing start-up of equipment mounted with a UVLO circuit, and executes a predetermined sequence when start-up is instructed by the start-up signal in a state the battery voltage is higher than the threshold voltage. A voltage control unit switches the threshold voltage based on the comparison signal and the start-up signal.

The invention discloses a power supplying apparatus and a display apparatus including the same. The power supplying apparatus is disclosed, in which an under voltage lock out function is not performed for instantaneous voltage dip even in case that a reference under voltage detection voltage is set at high level. The power supplying apparatus comprises an under voltage detector generating an under voltage lock out signal by detecting voltage dip of an input power and performing an under voltage protection function, wherein the under voltage detector delays the input power for a delay time, which is set, to generate the under voltage lock out signal.

The invention generally relates to a lighting technology, in particular to a control chip for LED (Light-Emitting Diode) driving. The chip comprises an error amplification module, a pulse width modulation module, a leading edge blanking module, an over-temperature protection module, and an under voltage lockout module, wherein the error amplification module enables a difference between a reference voltage of an in-phase inputting terminal and a feedback voltage of an inverting inputting terminal in the chip to be amplified; the pulse width modulation module enables the chip to achieve PWM (Pulse Width Modulation) logic control and enables a circuit to output a gate-driving signal of a power switch; the leading edge blanking module enables the chip circuit to eliminate a pulse peak current generated at the moment that the switch is conducted; the over-temperature protection module enables the chip to achieve a hysteresis function when a temperature is risen to an excessively high temperature; and the under voltage lockout module detects whether a voltage of a built-in analog voltage drain drain AVDD of the chip circuit reaches a threshold and outputs a response detection signal UVLO (under voltage lockout). Compared with the prior art, the control chip has the advantages that constant-voltage constant-current loop control is adopted; a loop can be stabilized in a primary side feedback mode; the control chip is simple in structure and small in volume; and an integral system can have high stability without secondary feedback or loop compensation.