A voltage regulator with dynamic voltage and frequency tracking is shown. The voltage regulator has power switches converting an input voltage into an output voltage, a control loop, a voltage comparator, and a target voltage generator. The control loop is coupled to the power switches to control the power switches to perform voltage regulation. The voltage comparator compares the output voltage to the target voltage to generate a first control signal to control the control loop. The target voltage generator generates the target voltage for the voltage comparator based on the frequency difference between the target frequency and the critical-path-related frequency, wherein the critical-path-related frequency depends on the output voltage. The power efficiency and response time are improved.

A period from when switching elements S1, S4 at first diagonal positions in a full-bridge inverter are turned off at the same time to when switching elements S2, S3 at second diagonal positions are turned on at the same time, is defined as T1, and a period from when the switching elements S2, S3 at the second diagonal positions are turned off at the same time to when the switching elements S1, S4 at the first diagonal positions are turned on at the same time, is defined as T2. With a total length of T1 and T2 set to be constant, the lengths of T1 and T2 are controlled to be changed every switching cycle.

A secondary side controller for a flyback converter includes an integrated circuit (IC), which in turn includes: a synchronous rectifier (SR) sense pin coupled to a drain of an SR transistor on a secondary side of the flyback converter; a capacitor having a first side coupled to the SR sense pin, the capacitor to charge or discharge responsive to a voltage sensed at the SR sense pin; a diode-connected transistor coupled between a second side of the capacitor and ground; a first current mirror coupled to the diode-connected transistor and configured to receive, as input current, a reference current from a variable current source; and a peak detect transistor coupled to the diode-connected transistor and to an output of the first current mirror. The peak detect transistor is to output a peak detection signal in response to detecting current from the capacitor drop below the reference current.

A failure detection circuit for a power switch transistor in a power switching converter is provided that compares a drive voltage for driving a gate of the power switch transistor to a plurality of thresholds. Based upon when the drive voltage crosses each threshold in the plurality of thresholds, a logic circuit determines whether a fault condition exists for the power switch transistor.

A bridge converter converts an input voltage into an output voltage, and includes a switching circuit, a transformer, a rectifying circuit, and a control module. The switching circuit includes a first switch and a second switch. The control module sets a first time period and a second time period. The control module provides a first control signal and a second control signal to control the switching circuit based on the output voltage. The control module fixes an operation frequency of the first control signal and the second control signal at the maximum frequency based on that the control module is set in a standby mode, and provides the first control signal and the second control signal in the first time period, and shields the first control signal and the second control signal in the second time period.

A secondary controller applied to a secondary side of a power converter includes a control signal generation circuit and a gate control signal generation circuit. The gate control signal generation circuit generates a gate control signal, and generates an injection signal according to the gate control signal. When a superposition voltage is less than a reference voltage, the control signal generation circuit generates a gate pulse control signal, wherein the gate pulse control signal corresponds to an output voltage of the power converter and the injection signal, the gate control signal generation circuit is further used for generating a gate pulse signal according to the gate pulse control signal, and the gate pulse signal is used for making a primary side of the power converter turned on.

A control unit (4) generates a control signal. A switching device (2) performs switching according to the control signal and generates a primary side input voltage from a supply voltage. A transformer (1) converts the primary side input voltage to a secondary side output voltage. A drive circuit (7) drives a power device (8) according to the secondary side output voltage. The control unit (4) includes a table listing a correspondence relationship between supply voltages and set values of control signals for obtaining a desired secondary side output voltage, refers to the table and generates the control signal having a set value corresponding to the supply voltage.

An electronic apparatus includes: an operator; and a power circuit configured to supply power to the operator, wherein the power circuit includes a first voltage converter configured to output a first voltage based on input power, and a power factor corrector (PFC) configured to output a second voltage by performing power factor correction for the first voltage, and supplies power based on the first voltage or the second voltage to the operator, wherein the power circuit stops an operation of the PFC, lowers the first voltage to have a level corresponding to the second voltage, and supplies power based on the lowered first voltage to the operator, based on power consumption of the operator lower than or equal to a predetermined value.

A control method of a switching circuit, a control circuit of the switching circuit, and the switching circuit are provided. The switching circuit includes an inductor or a transformer. An operational amplification is performed on an output feedback voltage and a first reference voltage of the switching circuit to obtain a compensation voltage. The compensation voltage controls an on-time of a main switch of the switching circuit. When the current of the inductor or the transformer drops to a threshold, after a time, the main switch is switched from off to on, and the output feedback voltage controls the time. When the output feedback voltage is higher than a first threshold voltage, the compensation voltage is pulled down. When the output feedback voltage is lower than a second threshold voltage, the compensation voltage is pulled up.

A switching control circuit for controlling switching of a transistor in a power supply circuit, such that the power supply circuit generates an output voltage at a target level. The switching control circuit includes an overload detection circuit detecting that a load of the power supply circuit is in an overload condition, when a voltage according to the output voltage reaches a predetermined level, an overcurrent detection circuit detecting that a load current is an overcurrent, when a current according to the load current reaches a predetermined value, an adjustment circuit decreasing the predetermined value, when a first time period has elapsed since the load becomes in the overload condition, a drive circuit driving the transistor such that the output voltage reaches the target level, and a control circuit causing the drive circuit to stop driving the transistor, after the load becomes in the overload condition or the load current becomes the overcurrent.