Abstract: An apparatus for a power supply with brownout protection and the method thereof are proposed. As a brownout condition occurs, the apparatus informs at least one microprocessor to process the shutdown process timely. The apparatus includes a power factor correction (PFC) circuit, and a bus capacitor generating a bus voltage by receiving an input voltage via the PFC circuit, and a PWM circuit generating multiple output voltages for the microprocessor, and a supervisor circuit generating a power-good signal in response to a proportional bus voltage, and a brownout circuit for disabling the boosting operation of the PFC circuit under a brownout condition. When the boosting operation is disabled, the bus voltage starts to fall. As the proportional bus voltage is lower than a threshold voltage, the supervisor circuit generates the power-good signal. Therefore, the microprocessor can process the shutdown procedure timely.

Abstract: A semiconductor resistor and a semiconductor process of making the same are provided. The semiconductor resistor comprises a substrate, a deep well, at least two contact regions, and a doped region. The substrate is doped with a first type of ions. The deep well is doped with a second type of ions, and formed in the substrate. The contact regions are heavily doped with the second type of ions, and formed in the deep well. The doped region is doped with the first type of ions, and is separated from the deep well by a distance. Wherein the first type of ions and the second type of ions are complementary, and the distance between the deep well and the doped region adjusts the breakdown voltage. In addition, the semiconductor process comprises the steps of forming a deep well containing a first type of ions; forming a doped region containing a second type of ions; forming an oxide layer; and forming at least two contact regions containing the first type of ions in the deep well.

Abstract: Voltage-controlled semiconductor structures, voltage-controlled resistors, and manufacturing processes are provided. The semiconductor structure comprises a substrate, a first doped well, and a second doped well. The substrate is doped with a first type of ions. The first doped well is with a second type of ions and is formed in the substrate. The second doped well is with the second type of ions and is formed in the substrate. The first type of ions and the second type of ions are complementary. A resistor is formed between the first doped well and the second doped well. A resistivity of the resistor is controlled by a differential voltage. A resistivity of the resistor relates to a first depth of the first doped well, a second depth of the second doped well, and a distance between the first doped well and the second doped well. The resistivity of the resistor is higher than that of a well resistor formed in a single doped well with the second type of ions.

Abstract: The present invention provides a LED driver for control the brightness of the LED. An inductor and a switch are connected in serial with the LED for control the current of the LED. A control circuit is developed to generate a control signal for switching the switch in response the LED current. A diode is parallel coupled to the inductor for freewheeling the energy of the inductor through the LED.

Abstract: A power converter includes a switch and a controller. The switch switches electrical power in the power converter. The controller generates a switching signal to control the switch in response to a first feedback signal associated with a voltage control loop and a second feedback signal associated with a current control loop. The controller can also allow the switching frequency to hop from frequency to frequency according to a digital pattern.

Abstract: A start-up apparatus for a power supply is presented. A charging path from an input voltage to a holding capacitor is cut off after the power converter starts up. The start-up apparatus includes a transistor having a drain supplied with the input voltage, and a source connected to the holding capacitor and an input of a start-up control unit. An output of the start-up control unit controls a switch and the transistor. The holding capacitor starts to be charged as the transistor is turned on. Once a voltage across the holding capacitor exceeds a start-up voltage, an internal control circuit is powered via the switch. Meanwhile, the transistor is turned off and the charging path is cut off. Furthermore, the start-up apparatus provides a hysteresis threshold voltage range for controlling the power converter.

Abstract: An energy transfer apparatus is developed for reducing a conductivity electromagnetic interference and manufacturing method. The energy transfer apparatus comprises a core, an input winding, an output winding, a supply voltage and a supply winding. The supply winding includes a shielding winding and an auxiliary winding. The input winding receives an input voltage for outputting the output voltage through the core and the output winding. The shielding winding and the auxiliary winding generate the supply voltage through the core. By setting of wire size and winding turns of the shielding winding, the conductivity electromagnetic interference is reduced for stabilizing an electric potential between an input-grounding terminal and an output-grounding terminal of the energy transfer apparatus.

Abstract: The present invention provides a LED driver for controlling the brightness of the LED. An inductor and a switch are connected in series with the LED for controlling the current of the LED. A diode is coupled in parallel to the inductor for freewheeling the energy of the inductor through the LED. A control circuit is developed to generate a control signal for switching the switch in response a reflected signal of inductor and the LED current. The LED current is further adjusted in response to the reflected signal. The value of the reflected signal is correlated to the LED temperature. Therefore the LED current can be programmed in accordance with the LED temperature.

Abstract: The present invention provides a LED driver for control the brightness of the LED. An energy-transferred element and a switch are connected in series with the LED for controlling the current of the LED. A diode is coupled to the energy-transferred element for freewheeling the energy of the energy-transferred element through the LED. A control circuit is developed to generate a control signal for switching the switch in response to the LED current. The LED current is further adjusted in response to a voltage signal of the LED. The value of the voltage signal is correlated to the LED temperature. Therefore the LED current can be programmed in accordance with the LED temperature.

Abstract: A soft-start apparatus for a power supply outputs a compensation signal to a PWM controller as the power supply starts up. Meanwhile, a pulse width of a switching signal outputted from the PWM controller gradually increases from an initial value to a determined value. The pulse width of the switching signal is then timely modulated in response to the load conditions thereat so as to prevent a power switch from over-voltage and over-current damage as the power supply starts up.

Abstract: An over-power protection apparatus with programmable over-current threshold for a power converter is provided. The over-power protection apparatus further provides an over-temperature threshold for protection purposes. The over-power protection apparatus is able to achieve over-power and over-temperature protection in response to the level of the driving signal of the power converter. In addition, the programmable over-current threshold of the present invention can be adjusted in response to various load conditions.

Abstract: The present invention proposes an over-voltage protection apparatus for a power converter. The over-voltage protection apparatus has an oscillator outputting a clock signal. Simultaneously, by comparing a sense signal with a threshold signal, an over-voltage comparative unit outputs a protection signal to an accumulating trigger unit. Next, the accumulating trigger unit is accumulating and counting the protection signal in response to the clock signal. The accumulating trigger unit further outputs an off signal to a latch unit as a period of the protection signal reaches a predetermined clock count. In response to the off signal, the latch unit outputs a latch signal to a driving output unit for disabling a switching signal to a power switch. Therefore, the power switch is turned off, and the object of the over-voltage protection can be accomplished.

Abstract: FI over-voltage crowbar provides lightning surge and ESD protection. The crowbar has a clamping transistor, which is driven by a mirror-amplifier. When an input surge voltage is higher than the voltage of a Zener diode, the mirror-amplifier will be switched on and generate an amplified voltage. The amplified voltage works together with a speed-up capacitor easily to switch on the clamping transistor. The mirror-amplifier has an n-transistor and two p-transistors, which provide sufficient headroom for the turn-on of a clamping transistor. The over-voltage crowbar of this invention rapidly drives the clamping transistor to low impedance, thereby achieving a higher sustenance rating for lightning surge and ESD in the integrated circuit.

Abstract: A PWM controller having a saw-limiter for power limit without input voltage sensing. The saw-limiter has an adder, a reference voltage, a scaler and a saw-tooth signal that is generated by the PWM oscillator. The saw-limiter produces a saw-limited voltage. The PWM controller will turn off its output when the current-sense input signal of the PWM controller is higher than the saw-limited voltage. The saw-limited voltage is equal to the reference voltage while a PWM switching period starts. After that, the amplitude of the saw-limited voltage will gradually increase until it reaches its maximum voltage. Subsequently, a saw-tooth like waveform is generated for the saw-limited voltage. The slope of the current-sense input signal is proportional to the line voltage. Therefore, a higher line voltage creates a sharp slope for the current-sense input signal, which will be restricted by a lower saw-limited voltage and produces a shorter PWM signal.

Abstract: An adaptive off-time modulator of a PWM controller is provided for power saving in the light-load and no-load conditions. The maximum on-time is kept as a constant and a bias current of the oscillator in the PWM controller is moderated to achieve the off-time modulation. Reduction of the bias current increases the off-time of the switching period. The bias current is a function of the supply voltage and the feedback voltage, which is derived from a voltage feedback loop. A threshold voltage defines the level of the light load. A limit voltage defines the low level of the supply voltage. A bias current synthesizer generates the bias current. Once the feedback voltage is decreased lower than the threshold voltage, the bias current is reduced linearly and the off-time of the switching period is increased gradually. When the supply voltage is lower than the limit voltage, the bias current increases and determines a maximum off-time of the switching period.

Abstract: A PWM controller has a line voltage input that allows using an input resistor for both start-up and power-limit compensation, thus saving the power consumption, easing the PCB layout, and shrinking the power supply size. In the integrated circuit, a mirrored-resistor used for the power limit compensation is composed of a mirror MOSFET, which is associated with an op amplifier, a constant voltage and a constant current to provide a precise resistance. Thus, by properly selecting the value of the input resistor, an identical output power limit for low line and high line voltage input can be achieved.

Abstract: A protection circuit for a boost power converter provides input under-voltage protection and output over-voltage and over-current protection. The protection circuit includes a control power MOSFET connected in series between the ground of the boost power converter and the ground of the load. The arrangement of the circuit makes it easy to drive the gate of an N-channel power MOSFET and is ideal for current-limiting control, which utilizes the Rds-on of the MOSFET as a current sensing element. Neither a specific gate-driver nor a current sensing resistor is required, and thus high efficiency can be achieved. Furthermore, the slow slew-rate at the gate of the MOSFET provides a soft-start to the load. The protection circuit includes a temperature compensation circuitry to offset the variation of the Rds-on. A time delay circuit prevents the switching elements and protection elements from overload damage.

Abstract: An interface apparatus for fan monitoring and control includes a current source amplifier that generates a programmable current in response to its input voltages. Associated with an output capacitor, which is able to reduce noise, the programmable current drives the fan at a desired speed. The rotating fan induces a ripple signal in the output capacitor, which is fed to a band-pass amplifier to produce a tachometer pulse. Through a buffer amplifier, an input control signal combined with a thermal sensor signal has direct control over the current source amplifier. Alternatively, a PWM circuit having a comparator, a ramp oscillator and the output of the buffer amplifier drives the current source amplifier in switching mode. Since the ramp oscillator can be synchronized by the input, both analog and pulse signals can function as the input control signals.

Abstract: A circuit of an adaptive slope compensator prevents instability in the current mode converter operating under a continuous mode. A timing capacitor, charged by a programmable current source, is used to generate a slope signal. The timing capacitor is discharged by a switching signal via a switching diode connection. The programmable current source is implemented by a transistor and three bias resistors. A voltage feedback signal of the converter is taken as an input to the programmable current source to control the slew rate and magnitude of the slope signal in response to the variations of the input voltage and the output power of the converter. The slope signal is added to a sensed current loop of the converter through an output diode and a resistor in series for providing necessary slope compensation.

Abstract: The present invention discloses a programmable pulse generator comprising a digital information processing system generating first and second program-controlled signals; a first digital-to-analog converter coupled to the digital information processing system, generating a first current signal in response to the first program-controlled signal; a second digital-to-analog converter coupled to the digital information processing system, generating a second current signal in response to the second program-controlled signal; and a differential amplifier having a feedback resistor, coupled to the first and second digital-to-analog converters respectively, and generating a pusle signal in response to the first and second current signals wherein the voltage and pulse width of the pulse signal are responsive to the first current signal, and the slew rate of the pulse is responsive to the second current signal.