National Semiconductor Corporation

Luan Minh Vu

Tuong Hai Hoang

Bruno Kranzen

Thomas Y Tse

Jonathan Robert Knight

Elroy M Lucero

Alexander Burinskiy

Gary A Brown

Neal L Horovitz

Larry Bradley

Siew Siong Teo

A battery temperature monitoring circuit, which has a cold comparator and a hot comparator, achieves high accuracy in a small cell size by utilizing a cold current optimized for the cold comparator and a cold reference voltage, and a hot current optimized for the hot comparator and a hot reference voltage, along with switching circuitry that provides the cold current to the cold comparator as the battery temperature approaches the cold trip temperature, and the hot current to the hot comparator as the battery temperature approaches the hot trip temperature.

Small highly accurate battery temperature monitoring circuit

Bandgap voltage reference circuitry capable of operating at very low power supply voltages. The current source for driving the core bandgap voltage reference is implemented with insulated gate field effect transistors having low threshold voltages. Voltage clamp circuitry protects the transistors from power supply voltage variations rising above a predetermined clamp voltage. An output amplifier with output biasing circuitry having a circuit structure similar to that of the core bandgap voltage reference ensures that the bandgap reaches the intended steady state of operation.

Bandgap in CMOS DGO process

A voltage regulation and battery charging system is provided. The system can simultaneously provide a regulated output voltage and charge a battery. The system includes a battery charger circuit, a voltage regulator circuit, and a voltage tracking circuit. A voltage divider is used to provide the voltage regulator circuit with a feedback voltage from the output voltage. Further, the voltage tracking circuit is operable to draw current from the voltage divider such that the regulated output voltage tracks the battery voltage if the battery voltage is above a threshold voltage. The voltage tracking circuit includes an op amp, a current mirror, and a resistor that is coupled between the inverting input of the op amp and the battery. The noninverting input of the op amp receives the threshold voltage. Additionally, the output of the op amp is coupled to the gates of the transistors in the current mirror.

Apparatus and method for control supply output voltage techniques to track battery voltage

A voltage regulation and battery charging system is provided. The system may include a switching regulator selection control circuit, two switching regulator controller circuits, two power transistors, a common synchronous transistor, a common LC circuit, and a battery charger circuit. The two switching regulator controller circuits may synchronously switch the two power transistors and the one common synchronous transistor. One of the switching regulator controller circuits may receive voltage from an AC adapter and the other may receive voltage from the battery. The first switching regulator controller circuit is employed to provide system power when the AC adapter is connected. When the battery is used to provide the system power, the second switching regulator controller circuit is used to down-convert the battery voltage to provide the system power.

Apparatus and method for magnetic charger IC for batteries with recycling of the LC filter for re-use as a battery step-down converter

A voltage regulation and battery charging system is provided. The system may include a switching regulator selection control circuit, two switching regulator controller circuits, two power transistors, a common synchronous transistor, and a common LC circuit. The two switching regulator controller circuits may synchronously switch the two power transistors and the one common synchronous transistor. One of the switching regulator controller circuits may receive a voltage from an AC adapter and the other may receive a voltage from a USB port. Further, the switching regulation selection control circuit selects which of the two switching regulator controller circuits controls the regulation of the system output voltage employing the common LC filter.

Apparatus and method for dual source, single inductor magnetic battery charger

Circuitry for powering a load and charging of a battery from a power source by a smart power supply is provided. The smart power supply controls the maximum current for battery charging based in part upon variables such as the maximum rate of charge of the battery and maximum source current. The smart power supply is thus capable of providing the power requested by the load, and use the remaining power for battery charging.

Battery charger that employs current sharing to simultaneously power an application and charge a battery

A circuit for regulating a sensed current in a power transistor is provided. The circuit is configured to sense if the drain current of the power transistor has reached a limit current I. A sense transistor is arranged in an m:1 current mirror relationship with the power transistor. Additionally, a current sink that is coupled to the drain of the sense current is also configured to sink a current approximately equal to I/m. Further, a comparison circuit is configured to compare the drain voltages of the power and sense transistors. Also, if the drain current of the power transistor is less than I, a current sink pulls down the drain of the sense transistor, so that the drain voltage of the sense transistor is less than the drain voltage of the power transistor. However, if the level of the drain current of the power transistor reaches I, then Vds of the sense transistor would reach Vds of the power transistor, and the comparator would trip. Additionally, two switches are arranged to be open when switching currents flowing through the power transistor and sense transistors are each substantially zero. By opening the switches when these switching currents are each substantially zero, a false output (trip) of the comparison circuit can be prevented.

Apparatus and method for sensing current in a power transistor

A polysilicon fuse trim read cell utilizes a fuse structure in a single bit memory cell. When the fuse structure is blown, the memory cell can be read and its stored value retained as a digital output. The cell uses no power in the steady state.

Polyfuse trim read cell

Cascoded transistors can be used to allow circuits to operate at higher operating voltages than the voltages at which individual transistors (formed by a given process) can function. However, common techniques for cascading transistors result in circuits being unable to operate at lower operating voltages. The present invention dynamically biases cascoded transistors in response to the level of the operating voltage, which can vary. Providing separate dynamic bias voltages for N-type and P-type CMOS devices allows circuits using this technique to achieve a wider operating voltage. The wider operating range makes circuits using this technique readily adaptable to a range of power supplies (e.g., different battery configurations) and applications (e.g., driving displays).

Dynamic biasing for cascoded transistors to double operating supply voltage

A band-gap filter circuit is disclosed for use in a voltage regulator. A capacitor charger (or &ldquo;cap charger&rdquo;) circuit quickly charges a filter capacitor when power is applied to the voltage regulator circuit. At start-up, the cap charger begins charging the filter capacitor. Once an output node equals or nearly equals the voltage at the input node, the cap charger shuts off. The circuit provides a very fast turn-on time, reaching 95% of its steady state value within 200 microseconds, thus overcoming the long turn-on times associated with other designs. The present invention may be utilized in power sensitive applications, such as cellular telephones, that wish to shut off the voltage regulator in order to conserve power.

Growing community of inventors

San Jose, CA, United States of America

Luan Minh Vu