Abstract: A charger for a portable device includes a USB detector connected to a data pin to detect the effective resistance on the data pin before a USB transceiver is enabled, to identify USB or adapter plug in and control a charging current for a battery accordingly.

Abstract: A charger for a portable device includes a USB detector connected to a data pin to detect the effective resistance on the data pin before a USB transceiver is enabled, to identify USB or adapter plug in and control a charging current for a battery accordingly.

Abstract: The present invention discloses a buck-boost switching regulator, and a control circuit and a method therefor, to convert an input voltage to an output voltage. The control method comprises: obtaining a feedback signal relating to the output voltage; comparing the feedback signal with a reference voltage to generate an error amplified signal; when the error amplified signal is between a first voltage (V1) and a second voltage (V2), causing the switching regulator to operate in a buck conversion mode; when the error amplified signal is between a third voltage (V3) and a fourth voltage (V4), causing the switching regulator to operate in a boost conversion mode; and when the error amplified signal is between the second voltage and the third voltage, causing the switching regulator to operate in a buck-boost conversion mode in which each power switch operates according to a respective predetermined pulse width, wherein V1<V2<V3<V4.

Abstract: A fast start-up low-voltage bandgap reference voltage generator uses two current generators to provide a first current having a positive temperature coefficient and a second current having a negative temperature coefficient, respectively, and a resistor to generate a temperature independent output voltage according to the sum of the first and second currents. The current generator for providing the first current has a self-bias circuit which uses a single MOSFET to establish the first current, and thereby avoids error caused by mismatched MOSFETs.

Abstract: A hybrid battery charger includes a control circuit and a power stage. The control circuit includes an error amplifier to generate a first error signal and a second error signal according to an output voltage and an output current of the hybrid battery charger, a linear controller to generate a first control signal according to the first error signal, a PWM controller to generate a second control signal and a third control signal according to the second error signal, and according to a mode signal, a multiplexer to select the first control signal for the power stage to operate the hybrid battery charger in a linear mode, or the second and third control signals for the power stage to operate the hybrid battery charger in a switching mode.

Abstract: In an NMOSFET-base linear charger, a pair of common gate charging NMOSFET and sensing NMOSFET have their sources coupled together or virtually shorted to each other, so that these two NMOSFETs have a same gate-source voltage and thereby the sensing NMOSFET reflects the drain-source current of the charging NMOSFET on its drain-source current. From the drain-source current of the sensing NMOSFET, a current sensing signal is generated to control the gate voltage of the charging NMOSFET. By implementing the current source with NMOSFETs, the linear charger has smaller die area and less power loss.

Abstract: A power safety system includes a first MOS, a second MOS, a switch and a body controller. The first MOS is connected between a power input and a power output. The second MOSFET is connected between the power output and a charging output. The switch has an end connected to the body of the first MOS, and the opposite end switched between the source and the drain of the first MOS. A body controller controls the switch according to the voltage at the power input and the voltage at the power output, to connect the body of the first MOS to the source or the drain of the first MOS. By switching the switch, the first MOS will have a parasitic diode effective to prevent a reverse current from the power output to the power input.

Abstract: A current regulator includes a first current source to provide a reference current varying with a dimming step, and a second current source to generate a drive current for a white LED according to the reference current. The reference current and the dimming step have a relationship identical to or approximating a relationship between luminance and lightness perceived by human eyes. Thus, the white LED is controlled to have a linear variation of the luminance perceived by human eyes when the dimming step is changed.

Abstract: A light emitting diode (LED) driving apparatus is provided, and which includes a first operational amplifier (OPA) having a positive input terminal receiving a predetermined voltage related to a current flowing through an LED string; a first resistor having a first end coupled to a negative input terminal of the first OPA and a second end coupled to a ground; a power transistor having a gate coupled to an output of the first OPA, a drain coupled to a cathode of the LED string and a source coupled to the first end of the first resistor; an error amplifier having a first input terminal coupled to the gate of the power transistor, a second input terminal receiving a reference voltage and an output terminal outputting a control voltage; and a power conversion stage providing a DC voltage to an anode of the LED string according to the outputted control voltage.

Abstract: A LED driver is disclosed for providing a current for LED lighting. The LED driver includes an inductor and a controller having a power switch, and the inductor, the power switch and a LED to be driven are configured to be an asynchronous boost converter. Because the driven LED serves as a rectifier diode of the asynchronous boost converter, the controller may have fewer components and requires smaller die area.

Abstract: The phase node voltage or the PWM signal in an asynchronous boost converter is monitored to detect a phase node voltage ringing. When a phase node voltage ringing is detected, a detection signal is asserted to establish a bypass path to bypass the inductor of the converter. A charge bypass circuit is shunt to the inductor, and controlled by the detection signal to establish the bypass path. Due to the bypass path, the phase node voltage is maintained at a constant, and the phase node voltage radiation and input/output noise are eliminated.

Abstract: For output current detection of a voltage regulator, the currents in a high-side transistor and a low-side transistor of the voltage regulator are sensed and summarized to a summed current to flow through a setting resistor. The voltage variation on the setting resistor is monitored to provide a feedback signal for feedback control in the voltage regulator. This detection scheme removes the current sensing resistor from the charging current path of the voltage regulator to prevent efficiency loss on it, and is much less sensitive to noise interference because greater voltage variation is available by using a greater setting resistor.

Abstract: The present invention discloses an overvoltage protection (OVP) circuit for use in a charger circuit system, comprising: a power transistor electrically connected between a voltage supply and a battery; an OVP circuit which turns off the transistor when a voltage supply exceeds a threshold value; and a multiplexing circuit electrically connected between an output of the OVP circuit and the gate of the transistor. The present invention also discloses a charger circuit with an OVP function, comprising: a single power transistor electrically connected between a voltage supply and a battery; an OVP control circuit which turns off the power transistor when a voltage supply exceeds a threshold value; and a charger control circuit which controls the gate of the power transistor to determine a charge current to the battery when the voltage supply does not reach the threshold value.

Abstract: The present invention discloses a single wire transmission interface comprising: a signal detection circuit detecting level switchings of a transmission signal from a single wire, and generating an enable signal and a decoded signal corresponding to the transmission signal, the level switchings including first switchings from a first level to a second level and second switchings from the second level to the first level, wherein the enable signal starts according to one first switching of the transmission signal, and stops when no first switching occur in a predetermined period after one second switching of the transmission signal, and wherein rising edges (or falling edges) of the decoded signal correspond to the first switchings of the transmission signal; a counter, under enablement by the enable signal, counting a number of the rising edges (or the rising edges) of the decoded signal or the first switchings of the transmission signal, and generating a count; a single short pulse generator generating a shor

Abstract: For output current detection of a voltage regulator, the currents in a high-side transistor and a low-side transistor of the voltage regulator are sensed and summarized to a summed current to flow through a setting resistor. The voltage variation on the setting resistor is monitored to provide a feedback signal for feedback control in the voltage regulator. This detection scheme removes the current sensing resistor from the charging current path of the voltage regulator to prevent efficiency loss on it, and is much less sensitive to noise interference because greater voltage variation is available by using a greater setting resistor.

Abstract: The present invention discloses a dual power switch and a voltage regulator using the dual power switch. The dual power switch comprises a PMOS power switch and an NMOS power switch connected in parallel and operating according to corresponding predetermined conditions, respectively.

Abstract: The present invention discloses a universal serial bus (USB) charging circuit, comprising: a charging path for charging a battery from a USB host; a charging switch located on the charging path; a current sensing circuit for sensing current information on the charging path; a maximum available current detection circuit for detecting the maximum available current from the USB host; and a loop controller circuit for controlling the charging switch so that the charging current on the charging path is substantially equal to the maximum available current detected by the maximum available current detection circuit, wherein the maximum available current detection circuit detects the maximum available current during circuit initialization and stores it.

Abstract: The present invention discloses a boost driver circuit which converts an input voltage to an output voltage and supplies it to a load, the boost driver circuit comprising: a power transistor electrically connected with a node between the input voltage and the output voltage; a pulse width modulation driver circuit for controlling the operation of the power transistor; an output node electrically connected with the output voltage; a feedback node electrically connected with the load; a low voltage transistor electrically connected with the feedback node; and a clamp and fast discharge circuit electrically connected with the feedback node for discharging the feedback node when the voltage at the feedback node is higher than a predetermined voltage.

Abstract: A fast start-up low-voltage bandgap reference voltage generator uses two current generators to provide a first current having a positive temperature coefficient and a second current having a negative temperature coefficient, respectively, and a resistor to generate a temperature independent output voltage according to the sum of the first and second currents. The current generator for providing the first current has a self-bias circuit which uses a single MOSFET to establish the first current, and thereby avoids error caused by mismatched MOSFETs.

Abstract: A switching regulator includes a low-side switch having a body diode. During the low-side switch is on, a zero-current sense circuit monitors the inductor current of the switching regulator and triggers a signal to turn off the low-side switch when the inductor current falls down to a zero-current threshold, to prevent reverse inductor current from the output terminal of the switching regulator. A body-diode turn-on time controller monitors the turn-on time of the body diode and adjusts the zero-current threshold according thereto, and the turn-on time of the body diode can be reduced to an optimal interval subsequently. The self-adjustable zero-current threshold is adaptive according to the application conditions, such as the inductor size, input voltage and output voltage of the switching regulator.