A frequency measurement apparatus includes: a measurement period setting circuit that sets a measurement period based on a reference clock signal; a first counter circuit that counts the number of pulses of the reference clock signal in a period based on an input signal during the measurement period; a second counter circuit that counts the number of pulses of the input signal during the measurement period; a first frequency calculation circuit that calculates a first frequency; a second frequency calculation circuit that calculates a second frequency; and a frequency selection circuit that selects the first frequency or the second frequency as a frequency of the input signal.

A frequency measurement apparatus includes: a measurement period setting circuit that sets a measurement period based on a reference clock signal; a first counter circuit that counts the number of pulses of the reference clock signal in a period based on an input signal during the measurement period; a second counter circuit that counts the number of pulses of the input signal during the measurement period; a first frequency calculation circuit that calculates a first frequency; a second frequency calculation circuit that calculates a second frequency; and a frequency selection circuit that selects the first frequency or the second frequency as a frequency of the input signal.

A method for performing divided-clock phase synchronization in a multi-divided-clock system, an associated synchronization control circuit, an associated synchronization control sub-circuit and an associated electronic device are provided. The method may include: performing frequency division operations according to a source clock to generate a first divided clock and a second divided clock; performing phase relationship detection on the first divided clock according to the second divided clock to generate a phase relationship detection result signal; performing a logic operation on a first phase selection result output signal and the phase relationship detection result signal to generate a second phase selection result output signal; and outputting one of the second divided clock and an inverted signal of the second divided clock according to the second phase selection result output signal, for further use in a physical layer circuit.

A circuit includes a clock generator, a frequency divider, and a first biasing circuit. The clock generator generates a clock signal of a first frequency. The frequency divider includes a first pair of cross coupled transistors. The frequency divider produces the clock signal of a second frequency. The first biasing circuit is coupled with the first pair of cross coupled transistors of the frequency divider. The first biasing circuit is adapted to enable a change in a transconductance of the first pair of cross coupled transistors to stabilize a phase angle between the clock signal at the first frequency and the clock signal at the second frequency.

According to one aspect of embodiments, a driver circuit having an overcurrent protection function includes a control signal generating circuit that outputs a Pulse Width Modulation (PWM) control signal for controlling turning ON and OFF of the output transistor that supplies output current to a load; and a control circuit that generates a signal indicating an overcurrent state when a count value of an overcurrent detecting signal exceeds a predetermined number, which indicates that a value of an output current of the output transistor within the predetermined time interval exceeds a predetermined threshold value.

According to one aspect of embodiments, a driver circuit having an overcurrent protection function includes a control signal generating circuit that outputs a Pulse Width Modulation (PWM) control signal for controlling turning ON and OFF of the output transistor that supplies output current to a load; and a control circuit that generates a signal indicating an overcurrent state when a count value of an overcurrent detecting signal exceeds a predetermined number, which indicates that a value of an output current of the output transistor within the predetermined time interval exceeds a predetermined threshold value.

A method and system are provided for controlling transfer switch operations in a power distribution system. The method and system involve monitoring an electrical parameter of an electrical signal from a first power source associated with supplying power to a load; determining whether the electrical parameter satisfies a parameter threshold; selecting to increment or decrement a count value in accordance with the determination; and responsive to determining that the count value satisfies a first count threshold, initiating a start signal to start operation of a second power source to supply power to the load. The electrical parameter can be voltage or frequency, or other parameter(s) from which a power quality of the electrical signal may be evaluated. The electrical signal can be a single or polyphase electrical signal.

A method and system are provided for controlling transfer switch operations in a power distribution system. The method and system involve monitoring an electrical parameter of an electrical signal from a first power source associated with supplying power to a load; determining whether the electrical parameter satisfies a parameter threshold; selecting to increment or decrement a count value in accordance with the determination; and responsive to determining that the count value satisfies a first count threshold, initiating a start signal to start operation of a second power source to supply power to the load. The electrical parameter can be voltage or frequency, or other parameter(s) from which a power quality of the electrical signal may be evaluated. The electrical signal can be a single or polyphase electrical signal.

The present invention provides a fractional frequency divider, wherein the fractional frequency divider includes a plurality of registers, a control signal generator and a clock gating circuit. Regarding the plurality of registers, at least a portion of the registers are set to have values. The control signal generator is configured to generate a control signal based on an input clock signal and values in the at least a portion of the registers, wherein the control generator sequentially generates the control signal during each cycle of the input clock signal. The clock gating circuit is configured to refer to the control signal to mask or not mask the input clock signal to generate an output clock signal.

At least one embodiment of the present disclosure provides a frequency divider, an electronic device and a frequency dividing method. The frequency divider includes a duty cycle correction circuit and a frequency divider circuit. The duty cycle correction circuit is configured to receive a first clock signal, and perform a first processing on the first clock signal to generate a first processed signal. The frequency dividing circuit is configured to receive the first processed signal, and perform a second processing on the first processed signal to generate a second processed signal. The duty cycle correction circuit is further configured to receive the second processed signal, and perform a third processing on the second processed signal to generate a third processed signal. The frequency divider can correct the duty cycle of the output clock signal while dividing the frequency.