Abstract: The present disclosure provides a power transistor driving method, a driving circuit and a switching circuit. When the power transistor is an N-type component, a driving pole of the power transistor is pulled down in a first current, and when a time period recorded by the timer reaches a first time period, a pull-down switch is turned on or the driving pole of the power transistor is pulled down in a second current; the driving pole of the power transistor is pulled down by the pull-down switch; when a timer is started from a moment at which the power transistor is turned off, the first time period is higher than a time period from a moment at which a switching tube is turned off to a moment at which the change rate of the drain-source voltage of the power transistor along with the time is higher than the first slope.

Abstract: The present disclosure provides a power transistor driving method. When a power transistor is turned off, a drain-source voltage of the power transistor is detected, and when the power transistor is an N-type component, and a change rate of the drain-source voltage of the power transistor along with time is lower than a first slope threshold, the power transistor is pulled down in a first current; when the change rate of the drain-source voltage of the power transistor along with the time is higher than the first slope threshold, a driving pole of the power transistor is pulled down in a second current; and when the change rate of the drain-source voltage of the power transistor along with the time is lower than the first slope threshold again, a pull-down switch is turned on or the driving pole of the power transistor is pulled down in a third current.

Abstract: An active clamping flyback circuit is disclosed, comprising a flyback circuit, a clamping circuit and a clamping control circuit, wherein the flyback circuit comprises a transformer, a main transistor, and a freewheeling diode or a synchronous rectifier, an output feedback circuit is coupling to an auxiliary winding of the transformer and outputs a feedback voltage through a divided voltage; the clamping circuit comprises a first capacitor and a first transistor coupling in series, one end of the first capacitor is coupling to a high voltage end, one end of the first transistor is coupling to a common end of the main transistor and a primary winding of the transformer; the clamping control circuit adjusts a turn-off time of next switching cycle of the first transistor so that the first time of the next switching cycle is close to a first threshold.

Abstract: Disclosed a drive method, a drive circuit for a power switch and a power supply system. During the turning-on period of the power switch, which can be roughly divided into three processes, a current limiting module is used to limit the current flowing through the power switch for preventing current overshoot, a logic control module is used for controlling the current limiting module not to operate before the turning-on period and the control terminal of the power switch is turned off; during the turning-on period, a feedback circuit adjusts the gate voltage of the power switch for controlling the current flowing through the power switch to reach a predetermined limited value quickly and then maintain at the limited value until the power switch is fully turned on. The current limiting module can be employed in various embodiments.

Abstract: A circuit and a method for detecting a current zero-crossing point, and a circuit and method for detecting a load voltage are disclosed. The circuit for detecting current zero-crossing point includes: a load power supply circuit, a voltage-dividing resistor, a transistor switch, a zero-crossing detection circuit; the load power supply circuit includes: a load, a diode, and a transformer; one end of a primary winding of the transformer is connected with the operating voltage input terminal, the other end of the primary winding of the transformer is connected with a first end of the transistor switch and a first end of the voltage-dividing resistor, a second end of the voltage-dividing resistor and a second end of the transistor switch are connected with the ground, the load voltage is controlled by the transistor switch.

Abstract: Disclosed a battery balance circuit, a control method for battery balance and a battery system. The battery balance circuit is implemented on basis of a circuit structure having a plurality of cascaded balance modules, in which a judgement of abnormal states of batteries or balance modules is realized together with synchronizations of the detection of battery states and battery balance. When the judgement of abnormal states of batteries (including the abnormal states of battery voltages, battery temperatures and battery currents) is made, the balance modules stop balancing by transferring signals, meanwhile, when the balance modules restore from the abnormal state, they restore balance. The disclosure increases the judgement of abnormal states, and implements detection and alarm at abnormal states.

Abstract: A flyback switching power supply, comprising a main power switch, a transformer and a rectifier is described. The transformer comprises a primary winding and a secondary winding, the main power switch is connected with the primary winding, the rectifier is connected with the secondary winding. When the output voltage of the flyback switching power supply is lower than a first threshold value, the rectifier is controlled to be turned on for a transient period; by detecting the negative current flowing through the main power switch, performing integral operation on the voltage across the auxiliary winding, and sampling the peak voltage of the drain-to-source voltage of the main power switch for several times, whether the rectifier is turned on can be determined if the output voltage at the secondary side is lower than the threshold voltage, and the main power switch is controlled to be turned on accordingly.

Abstract: The present invention provides a synchronous rectification control circuit, a method and a flyback switching circuit. A drive circuit outputs a drive signal to control the turn-on and turn-off of a synchronous rectification transistor; a threshold comparison circuit controls the drive circuit to output a pull-up drive signal to turn on the synchronous rectification transistor when a drain-source voltage is lower than a preset low threshold voltage and controls the drive circuit to output a pull-down drive signal to turn off the synchronous rectification transistor when the drain-source voltage is higher than or equal to a preset high threshold voltage; a voltage regulation control circuit controls the drive circuit to output a drive signal for pulling up a voltage of the drive signal to a preset pull-up voltage high value when the drain-source voltage is lower than a preset voltage regulation reference value.

Abstract: A protection circuit and an illumination driving circuit are described herein. The protection circuit comprises a detection circuit, detecting a current flowing through a first switch to obtain a current detection signal and determining whether there is leakage at an input terminal according to the current detection signal; a control circuit, controlling the first switch to switch on intermittently, detecting the current flowing through the first switch by the detection circuit during a switch-on period of the first switch, and keeping the load at a disconnection state if the detection circuit determines there is leakage; and the first switch, connected to the input terminal, and a control terminal of the first switch being connected to the control circuit, and the first switch being controlled by the control circuit to be switched on intermittently. The present invention has the protection function and enhances safety during load removing and installation processes.

Abstract: A circuit and a method for detecting a current zero-crossing point, and a circuit and method for detecting a load voltage are disclosed. The circuit for detecting current zero-crossing point includes: a load power supply circuit, a voltage-dividing resistor, a transistor switch, a zero-crossing detection circuit; the load power supply circuit includes: a load, a diode, and a transformer; one end of a primary winding of the transformer is connected with the operating voltage input terminal, the other end of the primary winding of the transformer is connected with a first end of the transistor switch and a first end of the voltage-dividing resistor, a second end of the voltage-dividing resistor and a second end of the transistor switch are connected with the ground, the load voltage is controlled by the transistor switch.

Abstract: A flyback switching power supply, comprising a main power switch, a transformer and a rectifier is described. The transformer comprises a primary winding and a secondary winding, the main power switch is connected with the primary winding, the rectifier is connected with the secondary winding. When the output voltage of the flyback switching power supply is lower than a first threshold value, the rectifier is controlled to be turned on for a transient period; by detecting the negative current flowing through the main power switch, performing integral operation on the voltage across the auxiliary winding, and sampling the peak voltage of the drain-to-source voltage of the main power switch for several times, whether the rectifier is turned on can be determined if the output voltage at the secondary side is lower than the threshold voltage, and the main power switch is controlled to be turned on accordingly.

Abstract: This invention provides an active-clamp flyback circuit and a control method thereof. A voltage at the common end of the main power switch tube and the primary-side winding in active-clamp flyback circuit is a node voltage. After the first switch tube is turned off, when the node voltage reaches an input voltage for the first time, start timing. If the node voltage drops to a low threshold before the timing reaches a first time, a turn-off moment of the first switch tube in a next circle is advanced; and if the node voltage is greater than the low threshold when the timing reaches the first time, the turn-off moment of the first switch in the next circle is delayed. This invention can realize zero voltage switching for different input voltages and output voltages, which reduces an energy loss in the circuit.

Abstract: The present invention discloses an isolated switch-mode power supply, a control circuit and a control method thereof. The main power transistor and the synchronous rectifier transistor are connected respectively to the primary-side winding and secondary-side winding of the isolated switch-mode power supply. The voltage of the control terminal of the main power transistor starts to increase, the main power transistor is turned on gradually, the current flowing through the main power transistor starts to increase until reaches the predetermined current-limiting value; the current of the main power transistor is maintained at the current-limiting value by controlling the voltage of the control terminal of the main power transistor; the secondary-side synchronous rectifier transistor is turned off, the current of the main power transistor decreases from the current-limiting value to the normal operation value, and the main power transistor is completely in an ON condition.

Abstract: The present disclosure relates to a circuit and a method for overcurrent control and a power supply system including the same. When the system operates normally, a reference voltage has a constant value. When a short circuit or an overcurrent occurs at an output of the system, the reference voltage will be pulled down,. When the system is recovered from the short circuit or the overcurrent state, the reference voltage increases slowly up to a steady value. A feedback signal of an output voltage follows the reference voltage and increases slowly. Thus, an overshoot of the output voltage can be effectively eliminated to avoid damages to the system.

Abstract: A circuit and a method for detecting a current zero-crossing point, and a circuit and method for detecting a load voltage are disclosed.

Abstract: A power supply protection circuit and a method is described herein. The power supply protection circuit comprises a current control unit, a voltage feedback unit, and a current pull-up unit. The voltage feedback unit is connected to the current control unit, the voltage feedback unit obtains a feedback voltage of an output voltage and feeds back the feedback voltage to the current control unit, and the current control unit uses the feedback voltage to control the current control unit to regulate an output current. The current pull-up unit is connected to a feedback terminal of the voltage feedback unit, and the current pull-up unit provides the voltage feedback unit with a pull-up current to determine whether the feedback terminal of the voltage feedback unit is short-circuited.

Abstract: The present invention provides a control circuit and a control method for a switch circuit and a switching-mode power supply circuit. The control method comprises following steps: detecting an output voltage or an output current, and adjusting an upper limit value and a lower limit value of an inductor current according to a result of comparing the output voltage or the output current with the corresponding reference; and sampling the inductor current, and controlling a main switch transistor in the circuit to be switched off when a sampling current rises to the upper limit value, and controlling the main switch transistor to be switched on when the sampling current drops to the lower limit value. In the present invention, the inductor current is fast in response without overshoot, the output voltage drops very little, there is no overshoot in a process of voltage recovery, and circuit transient response is fast.

Abstract: There is provided a dimming circuit, a dimming method and a LED driving circuit. On the basis of the dimming of a dimmer, the circuit according to the disclosure generates a plurality of current reference signals corresponding to a plurality of loads in accordance with a dimming signal, to change a ratio of load currents of the plurality of loads, so that, the adjustment of color temperature is implemented, wherein the dimming signal represents the changes of switching operation or dimming speed of the dimmer, and the ratio of current load currents of the plurality of loads is latched or a predetermined ratio of load currents is latched. According to the disclosure, the dimmer can be used for directly adjusting color temperature, without the need for a MCU, so that, the system compatibility is improved and the cost is decreased.

Abstract: A control method, a control circuit and a device for a switching circuit are disclosed, for fixing a frequency of the switching circuit when the switching circuit is operated under CCM. The present disclosure is suitable to various switching circuits, and an application scope of the control method of the switching circuit can be extended. The control method comprises: starting measuring time at a rising edge of a turn-on signal of the first switch; reducing a turn-on time or a turn-off time of the first switch when a first measured time is reached, and the rising edge in a next cycle of the turn-on signal has not arrived; increasing the turn-on time or the turn-off time of the first switch when the rising edge in the next cycle of the turn-on signal arrives but the first measured time is not reached.

Abstract: A switching power supply using a power switch, and a drive circuit therefor are disclosed. This circuit includes a power supplying capacitor with distal end connected with control terminal of the power switch and proximal end to receive a voltage regulation signal generated by a first control signal and a pulse signal. The power switch may be turned on or off, depending on whether the first control signal is placed in a first state during which the voltage regulation signal is in pulse state with the voltage at said distal end made effective, or in a second state during which the voltage regulation signal is in low-level state with the voltage at said distal end made ineffective. A continuous drive and power supplying for the switching power supply is realized, and the capacitance of said capacitor is small, thereby facilitating circuit integration.