Delco Electronics Corporation

Delphi Technologies, Inc.

Brian K Good

Mark Russell Keyse

Seyed R Zarabadi

Mark Wendell Gose

Gregory J Manlove

Mark Billings Kearney

Edward H Honnigford

John Robert Shreve

William P Whitlock

Gregg Nelson Francisco

Rebecca A Christenson

An oscillator circuit includes an oscillation circuit producing a RAMP signal and at least two control signals STATE and STATE and a comparator comparing an externally produced error signal ERR with the RAMP signal. When the ERR signal is between minimum and maximum levels of the RAMP signal, the duty cycle of a PWMOUT signal of the oscillator circuit varies as a function of the difference between the ERR and RAMP signals, and preferably accounts for approximately 85% of the total period. When the ERR signal is less than or equal to the minimum level of the RAMP signal, the duty cycle of the PWMOUT signal is fixed at a first value which is preferably approximately 5% of the total duty cycle. When the ERR signal is greater than or equal to the maximum level of the RAMP signal, the duty cycle of the PWMOUT signal is fixed at a second value which is preferably approximately 90% of the total period. The three foregoing states of operation are established by the oscillation circuit as a function of the ratios of three capacitors relative to each other.

Variable duty cycle oscillator circuit with fixed minimum and maximum duty cycles

Rotatable tube scrubber

A conversion circuit is provided for converting a differential voltage to a single-ended voltage. The conversion circuit has an input circuit including first and second input lines for receiving a differential voltage that is produced by a magnetic sensor in response to rotation of a wheel. First and second buffers are coupled to the first and second input lines, respectively, of the input circuit and each provide a buffered output. The conversion circuit further includes a difference amplifier having a positive input coupled to the output of the first buffer and a negative input coupled to the output of the second buffer. The amplifier provides as an output the voltage difference between the first and second inputs as a single-ended voltage output. The output circuit further converts the single-ended voltage output into a series of voltage pulses which provide rotational speed information about the wheel.

Differential to single-ended conversion circuit for a magnetic wheel

In accordance with the teachings of the present invention, a fault detection circuit is provided which detects short circuits on differential leads associated with a magnetic sensor and modifies said differential voltage to avoid possible errors associated with a short circuit. The circuit includes a first and second input coupled to first and second signal lines for receiving a differential voltage. A first voltage comparator compares voltage potentials at the first and second signal lines so as to detect equal voltage crossings and provide an output in response thereto. A rectifier is coupled to the first and second signal lines in the output of the first comparator and has first and second outputs for producing positive half-wave voltage cycles with a voltage potential at each of the first and second lead lines. A second comparator is provided for comparing the half-wave voltage cycles with a first threshold voltage that represents a short circuit power source. A third comparator is provided for comparing the half-wave voltage cycles with a second threshold voltage that represents a short circuit to ground. The voltage potentials at the first and second signal lines are converted to separate single-ended voltages when one of the second and third voltage comparators detects a short circuit so as to correct for possible errors caused by the short circuit.

Fault detection scheme for a variable reluctance sensor interface having

In accordance with the teachings of the present invention, an adaptive threshold circuit is provided which develops a series of square-wave voltage pulses from an alternating differential voltage that is produced in response to the rotation of a wheel. The adaptive threshold circuit includes an input circuit for providing an input voltage in response to the alternating differential voltage. A first voltage comparator compares the input voltage with an adaptive analog threshold voltage and produces an output in response thereto which causes a rising edge of the square-wave voltage pulse. A second voltage comparator compares a selected portion of the input voltage with the adaptive analog threshold voltage and produces an output in response thereto. The adaptive threshold circuit further includes a binary counter having a reset input for receiving the first voltage comparator output and an enable input for receiving the second voltage comparator output and provides a plurality of binary outputs. The second voltage comparator output thereby enables the counter so as to detect a peak input voltage. A digital-to-analog converter receives the binary outputs from the binary counter and generates the adaptive analog threshold voltage as a function of a selected percent of peak voltage.

Variable reluctance sensor interface using a differential input and

An adaptive loading circuit is provided for adaptively attenuating an alternating differential voltage that is produced by a magnetic sensor in response to the rotation of a wheel while maintaining noise immunity. The circuit includes an input for receiving an input differential voltage from the magnetic sensor via first and second input lines. A resistive divider network is included which has a resistive load serially connected to each of the first and second input lines and a plurality of adaptively selectable parallel resistive loads connected between the first and second input lines. Combinations of the parallel resistive loads are adaptively selected when the input differential voltage exceeds predetermined voltage thresholds so as to divide the input differential voltage into a selected portion thereof as an output differential voltage. In addition, the parallel resistive loads may be selectively switched out when the input differential voltage drops below a low voltage threshold. The output differential voltage is then processed so as to achieve rotational speed information about the wheel.

Adaptive loading circuit for a differential input magnetic wheel speed

A crystal oscillator circuit that provides a low distortion clocking signal. The oscillator circuit incorporates an inverter circuit in combination with a diode connected transmission gate circuit. The transmission gate circuit includes two MOSFETs connected between input and output nodes of the inverter circuit. When the current at the input node goes high and the current at the output node goes low, one of the two transmission gate circuit MOSFETs will begin conducting such that current at the input node will be transferred to the output node, thus decreasing the voltage difference between the two nodes. Likewise, when the current at the output node goes high and the current at the input node goes low, the other MOSFET of the transmission gate circuit will begin to conduct such that current is transferred from the output node to the input node, again reducing the voltage difference between the input and output node. Additionally, the transmission gate circuit provides the impedance necessary to generate oscillation of the oscillator circuit at start-up to regulate the output voltage swing of the oscillator circuit.

Low distortion crystal oscillator circuit

A MOS hysteresis comparator having a source transistor bias circuit which generates a source current Is that compensates for temperature and manufacturing process variations, thereby providing a hysteresis characteristic which is substantially insensitive to such temperature and manufacturing process variations. The source transistor bias circuit includes a set of MOS transistors which replicate the comparator load currents which occur at the switch points of the comparator, and a source transistor which mirrors the sum of the replicated currents to form the source current Is of the comparator.

Comparator having temperature and process compensated hysteresis

An apparatus for developing a signal voltage that represents the angular position of the crankshaft of an internal combustion engine. The apparatus includes a variable reluctance sensor that has a pick-up coil. The sensor is associated with means driven by the crankshaft of the engine for causing an alternating voltage to be induced in the pick-up coil as the crankshaft rotates. The apparatus includes a negative voltage clamp which clamps the voltage of a junction of the clamp circuit to substantially ground potential during negative half-cycles of the alternating voltage induced in the pick-up coil. The clamp circuit is adapted to be connected to a control circuit that is an integrated circuit having a bulk substrate diode. The clamp circuit prevents forward biasing of the bulk substrate diode.

Crankshaft position voltage developing apparatus having a voltage clamp

Apparatus for developing a series of square-wave pulses from an alternating voltage that is generated in the pick-up coil of a variable reluctance sensor that is associated with a slotted wheel that is driven by the crankshaft of an internal combustion engine. The system has an adaptive control which comprises a peak detector, a capacitor and a voltage comparator. The capacitor is charged to a peak voltage that corresponds to the peak value fo the positive half-cycles of the alternating voltage. The comparator is connected to compare the peak voltage and a voltage that corresponds to the magnitude of the positive half-cycles. A diode is connected between the pick-up coil and the peak detector which prevents charging of the capacitor and accordingly prevents adaptive control until the voltage induced in the pick-up coil is high enough to cause the diode to conduct in the forward direction.

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Greentown, IN, United States of America

Brian K Good