Abstract: A single stage current sense amplifier is described that generates a differential output that is proportional to a current through a sense resistor. The voltage across the sense resistor is Vsense. The current sense amplifier includes a differential transconductance amplifier having high impedance input terminals. An on-chip RC filter filters transients in the Vsense signal. A feedback circuit for each leg of the amplifier causes a pair of input transistors to conduct a fixed constant current irrespective of Vsense, which stabilizes the transconductance. A gain control resistor (Re) is coupled across terminals of the pair of input transistors and has Vsense across it. The current through the gain control resistor is therefore Vsensex1/Re. A level shifting circuit coupled to each of the input transistors lowers a common mode voltage at an output of the amplifier. Chopper circuits at the input and output cancel any offset voltages.

Abstract: A single stage current sense amplifier is described that generates a differential output that is proportional to a current through a sense resistor. The voltage across the sense resistor is Vsense. The current sense amplifier includes a differential transconductance amplifier having high impedance input terminals. An on-chip RC filter filters transients in the Vsense signal. A feedback circuit for each leg of the amplifier causes a pair of input transistors to conduct a fixed constant current irrespective of Vsense, which stabilizes the transconductance. A gain control resistor (Re) is coupled across terminals of the pair of input transistors and has Vsense across it. The current through the gain control resistor is therefore Vsensex1/Re. A level shifting circuit coupled to each of the input transistors lowers a common mode voltage at an output of the amplifier. Chopper circuits at the input and output cancel any offset voltages.

Abstract: An efficiency measuring circuit may measure the efficiency of a DC-DC converter having a switching inductor with an internal DC resistance and a plurality of electronic switches that control current through the inductor. A duty cycle circuit may measure the duty cycle of current flowing through one of the electronic switches. A current sense circuit may measure the current flowing through one of the electronic switches. An inductor voltage sensor circuit may measure the voltage across the inductor. A computation circuit may compute the internal DC resistance of the switching inductor based in part on the duty cycle measured by the duty cycle circuit and the current measured by the current sense circuit. The computation circuit may also compute the efficiency of the DC-DC converter.

Abstract: An efficiency measuring circuit may measure the efficiency of a DC-DC converter having a switching inductor with an internal DC resistance and a plurality of electronic switches that control current through the inductor. A duty cycle circuit may measure the duty cycle of current flowing through one of the electronic switches. A current sense circuit may measure the current flowing through one of the electronic switches. An inductor voltage sensor circuit may measure the voltage across the inductor. A computation circuit may compute the internal DC resistance of the switching inductor based in part on the duty cycle measured by the duty cycle circuit and the current measured by the current sense circuit. The computation circuit may also compute the efficiency of the DC-DC converter.

Abstract: An oil level sensor for a vehicle includes a receiver tube oriented upright in the oil pan of the vehicle. A level tube is disposed in the receiver tube and below the level tube is a reference tube. A circuit is electrically connected to the tubes for outputting a signal representative of oil level in the oil pan. As the engine oil level decreases within the level tube, the output of the sensor drops. When the engine oil level is below the bottom of the level tube but higher than the top of the reference tube, the output reaches the lowest value. As the engine oil level continuous decreasing (below the top of the reference tube), the output increases for a first circuit configuration (i.e., level with reference tube), and will stay constant for the second configuration level.

Abstract: An analog signal gain circuit includes an input receiving an analog input signal defined by an ac signal component due to a driving force and a dc offset component independent of the driving force and an output providing an analog output signal defined by an amplified representation of the analog input signal and a dc offset component corresponding to a reference signal. A digital/analog feedback circuit includes a comparator having the reference signal as a switching threshold connected to an up/down counter having a number of digital outputs. The outputs of the up/down counter are connected to a D/A converter which converts the digital count to an analog feedback signal. The feedback signal is provided to the input of the analog signal gain circuit to minimize variations in the dc offset signal component of the analog output signal by compensating for the dc offset signal component of the analog input signal.

Abstract: An analog signal processing system for determining airbag deployment includes a first low pass filter receiving a conditioned analog accelerometer signal and providing an analog acceleration signal therefrom. A first comparator/latch circuit receives the analog acceleration signal and provides a first signal to a logic circuit. The analog acceleration signal is further provided to a first integrator which converts the signal to a first velocity signal and provides the first velocity signal to a second comparator/latch circuit which provides a second logic level signal to the logic circuit. A second low pass filter receives the analog acceleration signal and provides a low frequency analog acceleration signal to a third comparator/latch circuit which provides a third signal to the logic circuit.

Abstract: A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor and converts the differential voltage to current. First and second current sourcing circuits, each including a plurality of current sourcing branches, receives the current and provides current attenuation by switching in and out transistor-based current sourcing branches. The rectifier and differential to single-ended conversion circuit converts the variably attenuated currents to a voltage output.

Abstract: Circuitry (100, 100') for determining actuator position includes four MOS transistors (T1-T4) connected to each side of a bi-directional motor (10). The current flowing through the motor (10) at any given time is proportional to voltages developed across the internal impedances of the transistors (T1-T4). The resulting motor voltages are amplified and high-pass filtered to remove any DC offsets due to the signal amplification. The conditioned motor voltages are then compared to one or more threshold voltages and passed through a one shot circuit (120) to provide detectable pulses for each motor commutation event. Circuitry (106,107) is provided for counting pulses provided by the one shot circuit (120) and, based on a desired motor position, for providing a number of digital control signals to a digital control circuit (104).

Abstract: A variable reluctance sensor interface module having a variable attenuation circuit and a rectifier and differential to single-ended conversion circuit for operating in a current mode to attenuate a differential input voltage. The variable attenuation circuit receives an input differential voltage from a magnetic sensor and converts the differential voltage to current. First and second current sourcing circuits, each including a plurality of current sourcing branches, receive the current and provides variable current attenuation by switching in and out transistor-based current sourcing branches. The rectifier and differential to single-ended conversion circuit converts the variably attenuated currents to a voltage output.

Abstract: A cross-coupled latch circuit that is a one-time programmable latch that allows volatile temporary writes to the latch prior to permanent programming of the latch. The latch circuit includes first and second programmable FET devices that include poly-poly capacitators in series with the gate terminal of each device. A pair of PMOS FET devices combine with the programmable devices to make up the latch. The latch circuit includes other FET devices that are switched on and off depending on whether the latch is being permanently programmed, temporarily written to, or reset. A NAND gate is provided such that a logical high output on the NAND gate allows the first programmable device to be temporarily programmed with a logical one and permanently programmed with a logical zero. A NOR gate is provided such that a logical high on the NOR gate allows the second programmable device to be temporarily programmed with a logical zero and permanently programmed with a logical one.

Abstract: An accurate integrated oscillator circuit includes a first circuit generating a substantially temperature independent, or a linearly temperature dependent, reference current and a second circuit which is programmable to incrementally increase the reference current to a desired current level. A third circuit includes first and second capacitors and an oscillator output switchable between first and second output levels. The third circuit is responsive to a first charge value on the first capacitor, due to the reference current flowing therethrough, to switch the oscillator output to the first level while resetting the second capacitor to its uncharged state, and to a second charge value on the second capacitor, due to the reference current flowing therethrough, to switch the oscillator output to the second level while resetting the first capacitor to its uncharged state. The oscillator circuit is preferably formed of a single integrated circuit and has an adjustable center frequency.