US Pat. No. 9,730,283

DRIVERS AND DRIVING METHODS FOR A LED STRING, CAPABLE OF PROVIDING LED SHORT PROTECTION OR AVOIDING LED FLICKERING

LEADTREND TECHNOLOGY CORP...

1. A driver for driving a LED string consisting of LEDs, the driver comprising:
a current switch connected in series with the LED string between a power line and a ground line; and
a switched mode power supply, for powering the power line to regulate a signal representing a current passing through the
LED string, wherein the switched mode power supply comprises an enable node and a clamping circuit;

wherein an enable signal at the enable node is capable of switching the current switch; and
when a predetermined event occurs the clamping circuit clamps the enable signal to have a predetermined logic value, the current
switch thereby being kept either open or short.

US Pat. No. 9,337,739

POWER CONTROLLER WITH OVER POWER PROTECTION

LEADTREND TECHNOLOGY CORP...

1. A power controller with over power protection, capable of providing a pulse-width-modulation signal to control a power
switch, the power controller comprising:
a pulse width modulator for generating the pulse-width-modulation signal;
a first oscillator, coupled to the pulse width modulator, for determining a cycle time of the pulse-width-modulation signal;
a second oscillator, independent from the first oscillator, for determining a maximum over power duration when the cycle time
is determined by the first oscillator; and

an over power detector for detecting an occurrence of an over power event;
wherein when the over power event lasts for the maximum over power duration, the pulse-width-modulation signal switches OFF
the power switch constantly;

wherein the first oscillator is controlled by a compensation voltage in association with an output power of a power supply;
wherein when the compensation voltage is about a preset over-power voltage, the first oscillator provides a first constant
frequency;

when the compensation voltage exceeds the preset over-power voltage, the first oscillator provides a second constant frequency
higher than the first constant frequency; and

the occurrence of the over power event is determined by comparing the preset over-power voltage and the compensation voltage.

US Pat. No. 9,077,250

CONSTANT CURRENT CONTROL UNITS AND CONTROL METHODS THEREOF FOR PRIMARY SIDE CONTROL

LEADTREND TECHNOLOGY CORP...

1. A constant current control unit, for a switched mode power supply with primary side control, wherein the switched mode
power supply has a power switch and an inductive device, the constant current control unit comprising:
a voltage-waveform detector, comprising a comparator with two inputs receiving a feedback voltage signal and a delayed signal
respectively to determine a discharge time of the inductive device when the power switch is OFF by comparing the feedback
voltage signal with the delayed signal, wherein the feedback voltage signal is provided from a reflective voltage of the inductive
device and the delayed signal is generated by delaying the feedback voltage signal; and

a constant current controller for generating an integral result according to the discharge time and a current-sense signal,
wherein the current-sense signal is provided based on a current flowing through the inductive device;

wherein the integral result is used for controlling the power switch to stabilize a maximum average output current of the
switched mode power supply; and

wherein the voltage-waveform detector comprises a low-pass filter, for low passing the feedback voltage signal to generate
the delayed signal, and the low-pass filter is connected between the two inputs.

US Pat. No. 9,059,638

CONTROL METHODS AND APPARATUSES FOR SWITCHING MODE POWER SUPPLIES

LEADTREND TECHNOLOGY CORP...

18. A controller for driving a power switch, comprising:
a driver comprising:
a high-side driver for turning ON the power switch by providing to a control node of the power switch a driving current to
raise a voltage at the control node; and

a low-side driver for turning OFF the power switch by providing to the control node another driving current to lower the voltage;
a control logic for controlling the driver; and
a condition decider coupled to the control logic, for terminating a dead time according to a conduction current passing through
the power switch;

wherein during the dead time, both the high-side and low-side drivers are disabled, not driving the control node of the power
switch.

US Pat. No. 9,301,364

DRIVERS AND DRIVING METHODS FOR A LED STRING, CAPABLE OF PROVIDING LED SHORT PROTECTION OR AVOIDING LED FLICKERING

LEADTREND TECHNOLOGY CORP...

1. A driver for driving a LED string consisting of LEDs, the driver comprising:
a current switch connected in series with the LED string between a power line and a ground line; and
a switched mode power supply, for powering the power line to regulate a signal representing a current passing through the
LED string, wherein the switched mode power supply comprises an enable node and a clamping circuit;

wherein an enable signal at the enable node is capable of switching the current switch; and
when a predetermined event occurs the clamping circuit clamps the enable signal to have a predetermined logic value, the current
switch thereby being kept either open or short;

wherein the predetermined event is the signal exceeding a predetermined value, and when the predetermined event occurs the
clamping circuit clamps the enable signal to be deasserted and to make the current switch open, thereby providing LED short
protection.

US Pat. No. 9,215,773

CONTROL METHODS AND BACKLIGHT CONTROLLERS FOR LIGHT DIMMING

LEADTREND TECHNOLOGY CORP...

1. A control method for light dimming, comprising:
providing a dimming condition signal, wherein a first logic value of the dimming condition signal represents a light emitting
device is expected to be emitting light, and a second logic value of the dimming condition signal represents the light emitting
device is expected not to be emitting light, wherein the duration when the dimming condition signal is at the first logic
value is a dimming-ON time;

providing, in the dimming-ON time, a close loop to make a power converter convert electric energy to the light emitting device
such that the light emitting device is capable of emitting light, wherein a power-ON time is the duration when the power converter
converts electric energy to the light emitting device; and

continuing, when the dimming condition signal is switched to be at the second logic value and the dimming-ON time is less
than a minimum power-ON time, the power converter converting the electric energy to the light emitting device so as to keep
the power-ON time not less than the minimum power-ON time.

US Pat. No. 9,621,027

POWER SUPPLIES AND CONTROL METHODS CAPABLE OF IMPROVING POWER FACTOR DURING LIGHT LOAD

LEADTREND TECHNOLOGY CORP...

1. An apparatus capable of improving power factor of a power supply powered by a high power line and a ground power line,
wherein the power supply comprises a power switch, the apparatus comprising:
a line voltage detector, for providing a scaled voltage to represent a line voltage of the high power line; and
an ON time controller, comprising:
a valley voltage detector, for providing, in response to the scaled voltage, a valley representative representing a valley
voltage of the line voltage;

wherein the ON time controller controls an ON time of the power switch in response to the valley representative; and
wherein when the valley voltage increases the valley representative makes the ON time increase.

US Pat. No. 9,673,720

SYNCHRONOUS RECTIFICATION CONTROLLER AND RELATIVE DEAD-TIME CONTROL METHOD

LEADTREND TECHNOLOGY CORP...

1. A synchronous rectification control method, suitable for a switching mode power supply with a synchronous rectifier, comprising:
providing a synchronous rectification controller with a first pin;
sampling a pin voltage at the first pin to generate a sampled voltage;
after the sampling, providing a detection current flowing out of the synchronous rectification controller from the first pin;
generating digital dead-time control signals in response to a difference between the pin voltage and the sampled voltage;
controlling the synchronous rectifier based upon the digital dead-time control signals to determine a dead time of the synchronous
rectifier;

comparing the sampled voltage with the pin voltage to generate an analog gap signal;
converting the analog gap signal into digital signals; and
latching the digital signals to provide the digital dead-time control signals.

US Pat. No. 9,800,135

RIPPLE SUPPRESSOR

LEADTREND TECHNOLOGY CORP...

14. A ripple suppressor, comprising:
a voltage-controlled current source with a control node, a first channel node and a second channel node, wherein a control
voltage at the control node controls a channel current through a path connecting the first and second channel nodes, and the
voltage-controlled current source receives a current-setting signal to generate the control voltage, so as to stabilize the
channel current in response to the current-setting signal;

a stabilizer coupled to the first channel node for generating the current-setting signal, wherein the stabilizer at least
provides low-pass filtering to substantially stabilize the current-setting signal in response to a first channel voltage at
the first channel node; and

an auto-calibration circuit for controlling the stabilizer in response to the control voltage, so as to make the control voltage
in compliance with a first predetermined condition;

wherein the first predetermined condition is that the control voltage is substantially limited under a predetermined top limit,
or that the control voltage has an average substantially equal to a predetermined value.

US Pat. No. 9,608,531

TIMING CONTROL METHOD AND APPARATUS FOR SYNCHRONOUS RECTIFIER USING ESTIMATED DURATION SIGNAL

LEADTREND TECHNOLOGY CORP...

1. A timing control method, suitable for a switching mode power supply with a synchronous rectifier, comprising:
generating a present duration signal at a first capacitor, wherein the present duration signal corresponds to a discharge
time when the synchronous rectifier is operated in a first condition;

providing an estimated duration signal at a second capacitor;
controlling the synchronous rectifier based on the estimated duration signal;
during a period of time when the synchronous rectifier is operated in a second condition different from the first condition,
updating the estimated duration signal by charge sharing between the first and second capacitors;

providing a current source to generate a charge current charging the first capacitor;
connecting a resistor between the current source and the first capacitor; and
comparing a voltage at a joint node between the resistor and the current source with the estimated duration signal to control
the synchronous rectifier.

US Pat. No. 9,723,664

CONTROL METHODS AND POWER CONVERTERS SUITABLE FOR TRIAC DIMMING

LEADTREND TECHNOLOGY CORP...

1. A power converter suitable for converting an input power source into an output power source, the power converter comprising:
a power controller powered by an operation power source with an operation voltage, comprising:
a high-voltage pin coupled to the input power source;
a high-voltage device capable of draining a conduction current from the input power source via the high-voltage pin;
a high-voltage startup control circuit, for detecting the operation voltage;
a cutoff-time detection circuit for detecting an input voltage of the input power source to provide a detected voltage; and
a demultiplexer coupled to the high-voltage device, the high-voltage startup control circuit and the cutoff-time detection
circuit, for forwarding the conduction current to the operation power source during a startup procedure and to a ground line
when the detected voltage is below a setting voltage;

wherein the conduction current charges the operation power source during the startup procedure; and
the conduction current goes through the high-voltage device and does not charge the operation power source when the detected
voltage is below the setting voltage.

US Pat. No. 9,774,267

POWER SUPPLIES AND CONTROL METHODS SUITABLE FOR SEQUENTIALLY TRANSMITTING COMMAND BITS FROM SECONDARY SIDE TO PRIMARY SIDE

LEADTREND TECHNOLOGY CORP...

1. A control circuit suitable for a power supply with a primary side and a secondary side galvanically isolated from each
other, wherein the power supply comprises a transformer with a primary winding and a secondary winding magnetically coupled
to each other, the primary winding and the secondary winding are located in the primary side and the secondary side respectively,
and the transformer is configured to transfer electric energy from the primary side to the secondary side and to build an
output power source in the secondary side, the control circuit comprising:
a primary-side controller in the primary side, configured to control a current through the primary winding; and
a secondary-side controller in the secondary side, powered by the output power source, configured to provide a command code
with several command bits sequentially transmitted to the primary-side controller so as to set an operation mode that the
primary-side controller operates in;

wherein the primary-side controller determines a voltage rating of the output power source based upon the command code with
the command bits.

US Pat. No. 9,825,534

DUMMY LOAD CONTROLLERS AND CONTROL METHODS FOR POWER SUPPLIES CAPABLE OF QUICKLY LOWERING OUTPUT VOLTAGE AT OUTPUT NODE

LEADTREND TECHNOLOGY CORP...

11. A dummy-load control unit, suitable for a power supply with a primary winding and a secondary winding isolated from each
other, wherein the secondary winding is configured to de-energize and to build an output voltage at an output node for powering
a load, the dummy-load control unit comprising:
a detection node coupled to the secondary winding;
a first comparator with a first input coupled to the detection node, a second input coupled to a reference voltage and an
output providing a comparison result;

a debounce circuit coupled to the first comparator for turning on a timeout signal when the comparison result has stayed in
a first predetermined value for a predetermined reference time;

a second comparator for comparing the output voltage with a predetermined voltage; and
a logic coupled to the debounce circuit and the second comparator;
wherein when the output voltage exceeds the predetermined voltage and the timeout signal is turned on, the logic provides
a discharge path for discharging the output node to lower the output voltage.

US Pat. No. 9,974,124

LED CONTROLLERS FOR DIMMING AT LEAST ONE LED STRING

LEADTREND TECHNOLOGY CORP...

1. A control circuit capable of controlling the light dimming of a light emitting device, the control circuit comprising:a current driver, in response to a dimming signal, for selectively causing a driving current flowing through the light emitting device, wherein the dimming signal is capable of defining a dimming ON period and a dimming OFF period;
a pulse-width modulator for generating a PWM signal to control a power switch, in order to build up a driving voltage at a power node of the light emitting device, wherein the PWM signal is generated in response to a compensation signal;
a feedback circuit, based upon a feedback voltage from the light emitting device, for driving a compensation capacitor to generate the compensation signal; and
a decoupling circuit, for defining a decoupling period at the start of the dimming ON period and causing the feedback circuit to not drive the compensation capacitor during the decoupling period;
wherein the feedback circuit comprises a transconductor whose output is in high impedance during the decoupling period and the dimming OFF period.

US Pat. No. 10,075,082

SWITCHING MODE POWER SUPPLIES WITH FAST LOAD-TRANSIENT RESPONSE

LEADTREND TECHNOLOGY CORP...

1. A power supply with a primary side and a secondary side isolated from each other, the power supply comprising:a primary-side control circuit on the primary side, for controlling a power switch to convert an input power source on the primary side into an output power source on the secondary side, wherein the output power source has an output voltage; and
a secondary-side control circuit on the secondary side, for detecting a falling rate of the output voltage and sending information to the primary-side control circuit when the falling rate exceeds a predetermined rate;
wherein, in response to the information, the primary-side control circuit starts a new switching cycle of the power switch; and
wherein the secondary-side control circuit comprises:
a voltage-to-current converter for converting the output voltage into a corresponding current;
a track-and-hold circuit for holding a sample current during a hold time, where the sample current equals to the corresponding current at the beginning of the hold time; and
a decider for determining whether the sample current exceeds a summation of the corresponding current and a reference current during the hold time, so as to determine whether the falling rate exceeds the predetermined rate.

US Pat. No. 9,917,523

CONTROL METHODS AND SWITCHING MODE POWER SUPPLIES WITH IMPROVED DYNAMIC RESPONSE AND REDUCED SWITCHING LOSS

LEADTREND TECHNOLOGY CORP...

1. A control method for a switching mode power supply with a transformer and a power switch, comprising:
providing a PWM signal to control the power switch, wherein the PWM signal has a switching frequency;
detecting a cross voltage of the transformer to provide a de-magnetization time;
controlling the switching frequency in response to a compensation voltage and a sleep signal, wherein the compensation voltage
is generated based on an output voltage of the switching mode power supply;

providing the sleep signal in response to the de-magnetization time and a current sense signal, wherein the current sense
signal is a representative of a winding current of the transformer;

making the switching frequency not less than a first minimum value if the sleep signal is deasserted; and
making the switching frequency not less than a second minimum value if the sleep signal is asserted,
wherein the second minimum value is less than the first minimum value.

US Pat. No. 9,882,494

SWITCHING-MODE POWER SUPPLIES CAPABLE OF OPERATING AT VALLEY SWITCHING, AND RELEVANT CONTROL METHODS

LEADTREND TECHNOLOGY CORP...

9. A power controller suitable for use in a power supply with an inductive device and a power switch, wherein when the power
switch is OFF the inductive device is capable of providing an oscillation signal with at least one signal valley, the power
controller comprising:
a valley detector coupled to the inductive device, for detecting the signal valley to provide a valley signal; and
a valley selector receiving the valley signal, for counting an occurrence number of the signal valley, comparing the occurrence
number with a lock number, and when the occurrence number and the lock number fit a predetermined condition, providing a pass
signal that allows the valley signal to make the power switch turned ON so a cycle time starts at a start moment;

wherein the valley selector checks if the start moment falls within an expectation window, and changes the lock number if
the start moment falls outside of the expectation window.

US Pat. No. 9,985,529

POWER CONTROL METHOD AND RELATED APPARATUS CAPABLE OF PROVIDING COMPENSATION TO INDUCTANCE VARIATION

LEADTREND TECHNOLOGY CORP...

9. A control circuit suitable for use in a power supply converting an input voltage into an output voltage, wherein the power supply includes a power controller controlling a power switch connected to an inductive device, and the control circuit is in the power controller and for compensating inductance variation of the inductive device, the control circuit comprising:a comparator with first and second inputs;
a first capacitor connected to the first input, wherein the comparator is configured to provide a sampling time having a length substantially independent from an ON time of the power switch, the input voltage and an inductance of the inductive device;
a sample-and-hold circuit for holding a sample voltage after the sampling time by sampling during the ON time a current-sense signal, a representative of a winding current through the inductive device; and
an output rating control unit for controlling the power switch in response to the sample voltage, so as to make the output voltage comply with an output rating.

US Pat. No. 10,193,456

PULSE WIDTH MODULATION CONTROLLER AND RELEVANT CONTROL METHOD HAVING MINIMUM ON TIME IN RESPONSE TO VOLTAGE PEAK OF LINE VOLTAGE

LEADTREND TECHNOLOGY CORP...

1. A PWM controller for providing to a power switch a PWM signal determining an ON time and an OFF time of the power switch, the PWM controller comprising:a peak detector for detecting a voltage peak of a line voltage generated by rectifying an alternating-current input voltage;
an OFF-time control unit for controlling the PWM signal and determining the OFF time in response to a compensation voltage, wherein the compensation voltage is in response to an output voltage of a power supply comprising the power switch and the PWM controller; and
an ON-time control unit for controlling the PWM signal and determining the ON time in response to the compensation voltage and the voltage peak, wherein the ON-time control unit is configured to make the ON time not less than a minimum ON time, and the minimum ON time is determined in response to the voltage peak;
wherein the ON-time control unit comprises a ramp signal generator for providing a ramp signal compared with the compensation voltage to determine the ON time; and
the ramp signal generator provides a charging current in response to the voltage peak to charge a capacitor and generate the ramp signal.

US Pat. No. 10,230,297

HIGH-VOLTAGE STARTUP CIRCUITS AND CONTROL METHODS THEREOF

LEADTREND TECHNOLOGY CORP...

11. A control method for high-voltage charging, in use of a high-voltage startup circuit comprising a ultra-high voltage transistor and a main NMOS transistor, wherein the main NMOS transistor has a first gate, the ultra-high voltage transistor is capable of sustaining an input voltage higher than 400V, and the ultra-high voltage transistor is connected in series with the main NMOS transistor via a joint node between a high-voltage pin and an operating voltage pin, the control method comprising:coupling the joint node to the first gate to turn ON the main NMOS transistor, so as to make a charging current flow through the high-voltage pin, the ultra-high voltage transistor, the main NMOS transistor and the operating voltage pin to increase an operating voltage at the operating voltage pin; and
decoupling the joint node from the first gate and pulling down a first gate voltage of the first gate, so as to turn OFF the main NMOS transistor and stop the charging current.

US Pat. No. 10,397,997

DIMMING CONTROLLERS AND DIMMING METHODS CAPABLE OF RECEIVING PWM DIMMING SIGNAL AND DC DIMMING SIGNAL

LEADTREND TECHNOLOGY CORP...

1. A dimming controller for dimming a light-emitting device, comprising:an input node for receiving a dimming signal;
a type identifier connected to the input node, for identifying whether the dimming signal is of a first type or a second type;
a signal converter connected to the input node, for generating a first signal in response to the dimming signal, wherein the first signal is of the first type; and
a multiplexer controlled by the type identifier, having two inputs receiving the first signal and the dimming signal respectively, wherein the type identifier makes the multiplexer forward the first signal to a driver driving the light-emitting device if the dimming signal is identified as the second type, and the dimming signal to the drive if the dimming signal is identified as the first type.

US Pat. No. 10,319,713

SEMICONDUCTOR DEVICES WITH ELECTROSTATIC DISCHARGE ROBUSTNESS

LEADTREND TECHNOLOGY CORP...

1. A semiconductor device with electrostatic discharge robustness, comprising:a semiconductor substrate of a first type;
a switch device, comprising:
a drain region formed on the semiconductor substrate, wherein the drain region is of a second type opposite to the first type;
a source region of the second type, formed on the semiconductor substrate and with a first arch portion facing inwardly toward a first direction, wherein the first arch portion at least partially surrounds the drain region; and
a control gate, structured to control electric connection between the drain region and the source region; and
an ESD protection device, comprising:
a first region of the first type formed on the semiconductor substrate; and
a second region of the first type formed on the semiconductor substrate and with a second arch portion facing inwardly toward a second direction, wherein the second arch portion at least partially surrounds the first region;
wherein the first direction is opposite to the second direction, and the switch device is a depletion-mode junction effect transistor.

US Pat. No. 10,348,208

POWER CONTROLLERS AND CONTROL METHODS THEREOF FOR SWITCHING MODE POWER SUPPLIES

LEADTREND TECHNOLOGY CORP...

1. A control method suitable for a switching mode power supply, the control method comprising:controlling a power switch according to a clock signal, to transfer electrical energy from an input power source to an output power source;
providing a feedback signal in response to an output voltage of the output power source; and
generating the clock signal in response to the feedback signal and an input voltage of the input power source, wherein the clock signal has a clock frequency determining a switching frequency of the power switch;
wherein when the feedback signal exceeds a first predetermined level, the clock frequency increases in response to decrease to the input voltage; and
when the feedback signal is under a second predetermined level lower than the first predetermined level, the clock frequency is independent from the input voltage.

US Pat. No. 10,347,756

HIGH-VOLTAGE METAL-OXIDE-SEMICONDUCTOR TRANSISTOR CAPABLE OF PREVENTING OCCURRENCE OF EXCEEDINGLY-LARGE REVERSE CURRENT

LEADTREND TECHNOLOGY CORP...

1. A high-voltage semiconductor device with a Schottky diode, comprising:a semiconductor substrate having an upper surface;
a body region of a first type, formed directly on the upper surface of the semiconductor substrate;
a drift region of a second type, formed directly on the upper surface of the semiconductor substrate, wherein the second type is opposite to the first type, and the drift region adjoins the body region to form a first junction therebetween;
a first metal electrode, positioned on the drift region to form a Schottky contact as the Schottky diode;
a first heavily-doped region of the second type, formed in the body region;
a second metal electrode, positioned on the first heavily-doped region to form an ohmic contact; and
a control gate structure comprising a gate electrode capable of controlling electric connection between the drift region and the first heavily-doped region;
wherein the semiconductor substrate contacts and shorts substantially to the body region; and
in view of second-type impurity dosage concentration, the first heavily-doped region is heavier than the drift region.