Abstract: An integrated circuit is disclosed that integrates a low current, high speed optical receiver with the primary side control functions of the power supply. This is further combined with an optical emitter to create a single component for feedback and control, providing improved performance and manufacturing. A method of providing feedback for the power supply using such an integrated optically coupled control circuit is also disclosed.

Abstract: A circuit and method for controlling a switching regulator utilize a combination of variable off-time control (or frequency control) and variable peak current control to achieve high efficiency at a wide range of load conditions. A non-linear control circuit receives an error voltage and generates a first control signal for controlling a frequency control circuit and a second control signal for controlling a peak current control circuit. The frequency control circuit and the peak current control circuit operate in conjunction over the entire range of load conditions with the frequency control dominates at light load (or low power) conditions and the variable peak current control dominates at moderate to heavy load (or high power) conditions. The switching regulator transitions smoothly between frequency control and peak current control with continous loop gain throughout the transition region.

Abstract: A switching power supply is disclosed for improving the no-load power drain of low-power mains operated supplies. The power converter utilizes a cascoded switch arrangement with a conventional high voltage power MOSFET and a low voltage, low gate charge MOSFET. Driving only the small low voltage device reduces the power required for gate drive. The disclosed configuration is also capable of generating a non-isolated auxiliary rail for powering its control circuitry utilizing the parasitic capacitance of the high voltage power devices as an element in a charge pump. The resulting power supply requires significantly fewer components.

Abstract: A low cost, low EMI air core inductor fabricated on printed circuit board for power conversion circuits is described. The inductive element combines the advantages of high efficiency and minimum board height requirements. It allows high frequency switching without adding undesired magnetic losses and minimizing the electro-magnetic interferences in form of radiated energy. The absence of any magnetic layer adds to the simplicity of the manufacturing process resulting in lower cost. This inductive element allows operation for the conventional and higher frequency step-up and step-down switching voltage converters minimizing the size and cost of output capacitors and reducing the output voltage ripple.

Abstract: Several methods to obtain process insensitive base-emitter forward voltage of a transistor are described. The main concept is to recognize that the transistor current gain is the parameter that affects this voltage the most with normal process variations. The use of transistor driven with known base current removes this error. In alternative, a method for compensating the base-emitter forward voltage variations is described. This is applicable to analog integrated circuits that utilize the base-emitter forward voltage of a transistor and in particular in applications that make use of either accurate voltage references, thermal sensing elements, solid state thermostats and very common thermal shutdown protection circuits.

Abstract: A Hard Disk Drive VCM positioning servo loop comprises an oversampling bitstream Digital to Analog converter. The oversampling DAC is a sigma-delta converter which yields higher resolution and lower noise than Nyquist-rate DACs. This allows driving the VCM with finer level of current control for higher track density. This approach can be implemented in the VCM driver chip (“combo chip”) or in the microprocessor device either in hardware or in software, reducing significantly the development and manufacturing cost. Furthermore this approach can be utilized in combination with a VCM actuation method known as “voltage mode drive” wherein the output of the sigma-delta converter represents the voltage to be applied directly to the VCM actuator. Furthermore this approach can be utilized for optical data storage motor positioning servo loops or any other motor positioning servo loops where high dynamic and resolution is needed.

Abstract: A linear low dropout voltage regulator is described that makes use of a depletion mode NMOS pass transistor and of a PMOS transistor in series to the NMOS transistor and connected to its drain. The depletion NMOS transistor assures low dropout operations, while the series PMOS transistor allows the current regulation even under the condition of shorted load. The same PMOS transistor may be used to disable the current in the load without generating a negative voltage at the gate of the depletion pass transistor. This regulator is inherently stable without the need for an output capacitor in parallel to the load.

Abstract: A Hard Disk Drive VCM positioning servo loop comprises an oversampling bitstream Digital to Analog converter. The oversampling DAC is a sigma-delta converter which yields higher resolution and lower noise than Nyquist-rate DACs. This allows driving the VCM with finer level of current control for higher track density. This approach can be implemented in the VCM driver chip (“combo chip”) or in the microprocessor device either in hardware or in software, reducing significantly the development and manufacturing cost. Furthermore this approach can be utilized in combination with a VCM actuation method known as “voltage mode drive” wherein the output of the sigma-delta converter represents the voltage to be applied directly to the VCM actuator. Furthermore this approach can be utilized for optical data storage motor positioning servo loops or any other motor positioning servo loops where high dynamic and resolution is needed.

Abstract: A linear low dropout voltage regulator is described that makes use of a depletion mode NMOS pass transistor and of a PMOS transistor in series to the NMOS transistor and connected to its drain. The depletion NMOS transistor assures low dropout operations, while the series PMOS transistor allows the current regulation even under the condition of shorted load. The same PMOS transistor may be used to disable the current in the load without generating a negative voltage at the gate of the depletion pass transistor. This regulator is inherently stable without the need for an output capacitor in parallel to the load.

Abstract: A clock changeover device comprising a first input port for accepting a first external clock signal, a second input port for accepting a second external clock signal, and an output port for outputting a selected one of the clock signals. The clock changeover device also comprises a circuit for generating a control signal as a function of one of the external clock signals. The control signal has a first state and a second state, the control signal being at the second state when the second external clock signal is coupled to the second input port, the control signal being at the first state when the second external clock signal is not coupled to the second input port. The clock changeover device further comprises an output circuit responsive to the control signal for coupling the first input port to the output port when the control signal is in the first state and for coupling the second input port to the output port when the control signal is in the second state.

Abstract: An adjustable power converter which allows the output voltage of the power converter to be controlled linearly by a programming resistor or a programming voltage is provided. The adjustable power converter includes a linear programming circuit which generates a current as a linear function of the programming voltage or the resistance of the programming resistor. The current is connected to the feedback loop of a conventional power converter such that the output voltage of the power converter is a linear function of the current. As a result, the output voltage of the power converter can be linearly adjusted by adjusting the programming voltage or the programming resistor.

Abstract: A programmable temperature detector for simple detection applications is described. The programmable temperature detector has three terminals and a plurality of temperature-transitions points from which to choose. A first terminal receives power from a supply, a second terminal receives a ground reference, and a third terminal provides an indication of an object's temperature crossing a selected temperature-transition point. The desired temperature transition point is specified by a single non-precision resistor coupled in series with the power terminal of the detector. The non-precision resistor and a power supply set a program signal, in the form of a current, into the power terminal of the detector. The programmable temperature detector comprises circuitry for quantizing the program signal into a discrete signal level and for selecting a temperature transition point in response.