Abstract: A voltage regulator for use in controllable bus terminators providing a source and a sink to a regulated output without clamping circuitry is disclosed. The regulator maintains a voltage at a node by sourcing current into the node when a cable line sinks current from the node and sinking current from the node when a cable line sources current into the node. By avoiding the use of clamping circuitry, a voltage deadband between the regulator output voltage and the clamp circuit voltage is avoided.

Abstract: A floating current mirror circuit is disclosed which achieves high open loop gain without additional voltage gain stages leading to frequency compensation and increased power dissipation. The output of the circuit has only a first pole and is designed to be coupled to a second current source, a base coupled to the first terminal of the diode, and an emitter coupled to the floating node. A second bipolar transistor has a base coupled to the collector of the first transistor, and emitter coupled to the floating node.

Abstract: An improved low voltage dropout regulation circuit is provided. The internal compensating capacitance coupled to the regulated output port is coupled to a virtual ground and the virtual ground is current buffered for coupling to the control electrode of the path element. For additional frequency compensation, particularly when the path element has a large capacitance, an additional internal compensating capacitance is coupled between the input of the dropout circuit and an output of a transconductance amplifier, which is responsive to the voltage at the regulated output port.

Abstract: An improved low voltage dropout regulation circuit is provided. The internal compensating capacitance coupled to the regulated output port is coupled to a virtual ground and the virtual ground is current buffered for coupling to the control electrode of the path element.

Abstract: A bi-mode circuit for driving an output load selectively couples the output load to a supply voltage source or to a low discharge voltage source such as ground using switches which are controlled by an input buffer in response to an input signal. A high input signal closes a first switch to provide a biasing current to first and second current amplifiers to turn on a first output transistor which couples the output load to the low reference voltage to discharge the output load. Conversely, a low input signal closes a second switch to provide the biasing current to a third current amplifier to turn on a second output transistor which couples the output load to the supply voltage source. When the input signal becomes high, rapid pulldown of a capacitive output load is achieved using a high internal pre-drive current provided by the first and second current amplifiers, in a first mode of operation.

Abstract: An improved output stage for a CMOS circuit is disclosed. In particular, the circuit drives both output transistors of a push-pull output in class AB operation for efficient power usage with low noise and distortion with a minimal number of components.

Abstract: A pulse detection and conditioning circuit senses and conditions commutation pulses produced by a DC permanent magnet motor to determine motor position. The pulses are sensed using a resistor coupled in series with the motor, so that motor current and the included pulses are continuously sensed, even during motor braking. The serially coupled resistor also provides for sensing and conditioning of pulses of both polarities produced by bi-directional operation of the motor. The pulse detecting and conditioning is performed by circuitry which performs amplitude qualification as well as frequency filtering to effectively detect valid commutation pulses to the exclusion of noise and other unwanted signals. Capacitors coupled to the motor and internal capacitors provide the frequency filtering, while the amplitude qualification is provided by a balanced differential gain stage coupled through an adjustable differential gain stage with adjustable gain to a unity gain comparator.

Abstract: A power supply controller includes a comparator for providing a regulated voltage when an input voltage exceeds a reference voltage, so that a reference voltage is provided to drive a load discharge circuit. When the input voltage is less than the reference voltage, such as during a startup or sleep mode of operation of the controller, the load discharge circuit is driven by an output pulldown circuit so as to maintain minimum functions within the integrated circuit of the controller including turnoff of an external MOSFET. The output pulldown circuit senses the resulting absence of the regulated voltage using a first transistor coupled to be biased into nonconduction when the regulated voltage is not provided. This biases a second transistor into conduction to maintain a transistor within the load discharge circuit conductive. In this manner, the output powers its own operation, including the pulldown thereof.

Abstract: A voltage reference circuit includes a band-gap reference circuit for providing a reference voltage and having breakpoint compensation to adjust the temperature coefficient of the reference voltage as a function of temperature. A thermal limit transistor biased by a voltage having a positive temperature coefficient begins conducting when the operating temperature reaches a predetermined value to provide a compensation current. The compensation current is added to the collector current flowing into one of a pair of transistors within the band-gap reference circuit, and a current controlled current source responds to an increase in collector current in the other one of the pair of transistors by making the collector currents flowing into both transistors equal. This increases the voltage drop across a pair of resistors to increase a band-gap voltage across a portion of an output divider network, to in turn increase the reference voltage provided across the entire divider network.