Abstract: An accelerometer or accelerator switch and its method of manufacture are disclosed. The device is fabricated from two substrates: a top substrate having a moveable mass, and a bottom substrate having at least one conductive plate. The top substrate is preferably a SOI substrate, and the mass and its suspending beams are formed in the silicon layer under which the insulator layer has been removed. The bottom substrate is preferably oxide. In one embodiment, the capacitance is formed using the mass as the first capacitor plate the conductive plate as the second plate. As the mass moves, the capacitance is detected to indicate the magnitude of the acceleration, or whether acceleration is above or below a threshold indicting an open or closed switch. The beams which suspend the mass can be serpentines, which make the device compact and render the mass more flexible. Alternatively, the bottom conductive plate can be split into two plates each coupling to the mass.

Abstract: A programmable amplitude ramp generator for an automotive voltage regulator includes a selection circuit (405) with an output (406) that provides a selection signal (407) with a plurality of states. A voltage reference circuit (401, 403) includes an output (410) that provides a different reference voltage dependent on each of the plurality of states of the selection signal (407). A resistive device (411) has an input (414) coupled to the output (410) of the voltage reference (401, 403), and an output (416). A gateable multi-resistive device (413) has an output (415) coupled to the output 416 of the resistive device 411. A coupleable resistive device (409) has an input (419) coupled to the output (410) of the voltage reference circuit (401, 403) and an output (421) coupleable to the output (416) of the resistive device (411) responsive to receipt of one of the plurality of states of the selection signal (407).

Abstract: A dual output temperature compensated voltage reference includes a voltage reference circuit (201) having a first output (203) for providing a first signal (204) dependent on temperature, and a second output (207) for providing a second signal (208) dependent on the first signal (204). A temperature dependence of the first signal (204) has a slope opposite a temperature dependence of the second signal (208). A cooperative device (209), such as a resistive divider (309, 311), combines the first and second signals (204, 208) and provides a third signal (212) dependent on the first and second signals (204, 208). Preferably, this apparatus is applied in a charge regulator including fault detection (109). The charge regulator (109) generates a charge voltage (110) dependent on the first signal (204) and a fault detection function is dependent on the third signal (212).

Abstract: A phase winding detector (50) is preferably used to detect alternator (11) rotation in an alternator charging system (10). The detector (50) receives a single winding phase output signal (at 39) and utilizes a sampling apparatus (71, 74, 76) to provide a sampled phase output signal (at 75). A comparison circuit (70) provides an output by comparing the phase output signal with the sampled phase output signal, whereby a detection of variation in the phase output signal is provided (at terminals 85, 87 and 51). After initial detection of variation of the phase winding output signal, preferably additional circuitry (77, 79, 83) results in comparing the phase winding signal with a fixed reference threshold (V.sub.ref). Detection of a phase winding output signal is implemented without use of a substantial DC blocking capacitor and is implemented by monitoring only one input signal terminal.

Abstract: A thermally dependent self-modifying voltage source (115) is constructed with a first reference circuit (301) having a control input (311), a primary output (117) dependent on the control input, and a thermally dependent secondary output (303). The thermally dependent self-modifying voltage source also includes a thermally dependent reference (309) with an output (307). The thermally dependent secondary output (303) of the first reference circuit (301) and output (307) of the thermally dependent reference (309) are coupled to inputs of an amplifier (305). The amplifier (305) has an output (313) coupled to the control input (311) of the first reference circuit (301), wherein the primary output (117) of the first reference circuit is dependent on the amplified difference between the thermally dependent secondary output (303) of the first reference circuit and the output (307) of the thermally dependent reference (309).

Abstract: In a circuit for overvoltage protection of a low voltage device (11) arranged to control a load (12) an energy storage capacitor (17) is connected to charge from supply (+V) while the device is controlled from a control circuit (100). During overvoltage, the controller is disconnected by switch means (15) and capacitor connected by switch means (16, 18) across the device to maintain it in an on state so that overvoltage device damage is prevented. The circuit is suited to transitory overvoltage conditions such as automotive load dump and to integration with the controlled device.

Abstract: A method for establishing a test mode in an electronic module (10) having an internal fault detector (26) that limits the current in an output transistor (Q1) when an abnormal signal level appears at an output pin (16). An abnormal signal level is intentionally established on the output pin to enable the fault detector, and such enablement is sensed to trigger the test mode within the module. Apparatus for implementing this method in a voltage regulator is also disclosed.

Abstract: A driver circuit for driving from the same output node (6) an inductive relay (34) and a non-inductive lamp (30) having a transistor (16) for driving the relay and second transistor (18) for driving the lamp and a third transistor (90) having its current electrodes coupled between the control electrodes of the first and second transistors for sensing an inductively-induced voltage at the output node when the first transistor means is disabled to cease driving the relay and for enabling the first transistor in response thereto to dissipate the inductively-induced voltage at the output node so as to protect the second transistor. Alternative couplings of the third transistor to the second transistor are also disclosed.

Abstract: A circuit (2) for use with an automotive voltage regulator (16), having: an input node (4) for receiving an input voltage (V.sub.BAT); an output node (12) for producing a regulated output voltage (V.sub.REG); a control node (18) for receiving a control signal from the voltage regulator; a first transistor (10) having its emitter connected via a protection diode (6) to the input node, its collector connected to the output node, and its base connected to the control node; an electrolytic input capacitor (8) connected between the first transistor emitter and ground; an electrolytic output capacitor (14) connected between the output node and ground; and a second transistor (32) having its emitter connected to the input node, its collector coupled to the output node, and its base for coupling to the voltage regulator. The second transistor allows the circuit to provide regulation at a lower input voltage, while retaining the protection diode.

Abstract: An automobile alternator regulator integrated circuit having a voltage-supply or -sense node (6) for connection to an external voltage, and a voltage clamp comprising: a pnp bypass transistor (Q1) having a base electrode, an emitter electrode coupled to the node and a collector electrode coupled to ground; a resistor (R1) connected between the base electrode and the node; a Zener diode (Z1-Z4) connected between the base electrode and ground for enabling the bypass transistor when the voltage at the node exceeds a predetermined value, whereby the voltage at the node is clamped to a voltage no greater than the predetermined value; and a fuse (F1) connected between the node and the emitter electrode so as to provide a subsequently identifiable cause of failure if the fuse becomes blown due to excess voltage while allowing subsequent operation of the integrated circuit if the clamp means fails but another part of the integrated circuit remains functional.

Abstract: A switchable filter has characteristics (e.g., time constant) that are changed by a low offset, bipolar switch that is turned off and on to periodically connect/disconnect an additional circuit element to the filter. The preferred embodiment is specially designed for use in an automotive voltage regulator.

Abstract: A bi-level control signal is applied to an FET while the FET's drain-to-source voltage is sensed. The control signal includes a first, relatively low test level followed by a second, relatively higher operating level. The magnitude and duration of the test level are selected to produce a non-destructive current in the FET, even if the load has been shorted. If the value of the sensed drain-to-source voltage is indicative of an abnormal load condition, the FET is turned off. Otherwise, the FET is turned on by the second, relatively higher operating level of the control signal.

Abstract: An interface circuit serves to rectify excitation energy inductively coupled to a transistor acting in a diode configuration to charge a reservoir capacitor which may then serve as a power source. Switch means under the control of an external functional circuit block is arranged to bias the transistor into a reverse operating mode to itself act as a switch to discharge energy from the reservoir into the coupling. In this way pulses may be back coupled to be detected at the excitation source. The timing of the back coupled pulses may be information bearing.

Abstract: Semiconductor device protection circuit (10) provides increased power dissipation (current) limits for FET (11) when lower FET temperatures exist. The FET drain to source voltage (V.sub.DS) is monitored to provide a current sense signal (54). When the current sense signal exceeds a predetermined reference limit signal (V.sub.REF,55), a control circuit (23, 32) reduces current (power dissipation) in the FET. Circuitry (24) provides the reference limit signal (V.sub.REF) with a predetermined temperature variation as a function of the sensed temperature of the FET whereby for low device temperatures higher power dissipation (current) limits for the FET are provided. An additional control circuit (21, 30) provides short circuit overcurrent protection by reducing current in the FET when sensed FET current exceeds a predetermined limit. A delay circuit (39) inhibits operation of at least the control circuit (20, 32) until a predetermined time (t.sub.1) after the FET is turned on.

Abstract: A regulator for a vehicle charging system senses when it applies and terminates excitation to the field winding of the charging system's alternator. When the excitation is applied to the field windings, the output of the alternator is connected to an input filter in the regulator so that the regulator can sense the alternator's output. When the excitation is terminated, the input filter is disconnected from the alternator's output to isolate the filter from voltage steps induced in the alternator's output by the turn-on and turn-off of the field excitation.

Abstract: Integrated circuit voltage regulator (60; 81; 91) is provided for use in a battery charging system (10) for providing excitation current to a field coil (13) of an alternator (11). The integrated circuit voltage regulator includes a transistor (70) which is selectively switched on and off to implement the prior art diesel diode (26) functions of providing initial field coil excitation current while preventing undesired current flow from an alternator voltage supply terminal (20) during subsequent field coil excitation current. The transistor (70) is provided as part of an integrated circuit and, therefore, eliminates the need for a diesel diode (26) external to the integrated circuit. In addition, use of the switched transistor (70) minimizes voltage drop loss when providing initial field excitation current. Constructing the transistor (70) as a PNP vertical substrate transistor minimizes integrated circuit area and simplifies integrated circuit topology.

Abstract: An improved dual limit solenoid driver control circuit is disclosed in which solenoid current is sensed and provided as an input to two separate comparators (24, 25). Each comparator receives, during a solenoid pull-in (initial) period (T.sub.1), fixed maximum and minimum reference threshold levels which determine the maximum and minimum current limits (I.sub.max, I.sub.min) for solenoid current during initial pull-in excitation. Subsequently during a hold period T.sub.2 following the pull-in period, each of the comparators receives different maximum and minimum thresholds so as to establish holding solenoid current limits (H.sub.max, H.sub.min). The outputs of the compartors are connected as inputs to a set/reset flip flop (32) whose output controls the operation of a solenoid driver circuit (15). A monostable multivibrator (33) reacts to an initial control pulse (41) to produce a predetermined pull-in time pulse (43) that results in the maximum and minimum pull-in solenoid current limits.

Abstract: A voltage regulator (11) provides a pulse width modulated voltage regulator output (40) to a drive circuit (37) to provide field coil excitation for a voltage generator (15-17) providing a charging signal for a battery (14). The voltage regulator output determines on/off states of an FET power switching device (28) coupled in series with a field coil (17) across a maximum power source voltage potential V.sub.BAT corresponding to battery voltage. The drive circuit includes a charge pump (26, 35, 36) with a low capacitance capacitor (26) coupled and decoupled across a source of voltage potential at a rate determined by a high frequency signal (41), provided by the regulator, having a frequency substantially in excess of the frequency of the voltage regulator output. The drive circuit includes a pair of switches (21, 35) which alternately couple one terminal of the capacitor to either battery voltage or ground potential in accordance with the voltage regulator output.

Abstract: An improved solenoid driver control circuit is disclosed in which solenoid current is sensed and provided as an input to a comparator means comprising two separate comparators (24, 25). The comparator means receives a solenoid current sense signal (45) and maximum and minimum reference threshold levels which determine maximum and minimum current limits (I.sub.max, I.sub.min ; H.sub.max, H.sub.min) for solenoid current during initial pull-in excitation and subsequent hold excitation. Pull-in time (T.sub.1) is defined by a monostable multivibrator (33) reacting to a control pulse (41) to produce a predetermined pull-in time pulse (43) such that the pull-in time is independent of sensed solenoid current. During pull-in time a boost driver switch (53) applies high boost voltage to a power source terminal (16) which supplies solenoid current, and in response to achieving the maximum pull-in current limit (I.sub.max) lower battery voltage is provided at the power source terminal.

Abstract: The circuit utilizes combinational logic and latching circuits to prevent damage to the regulator or to the battery of an automotive ignition system due to a serious fault such as the ignition being turned "on" but the engine/alternator not rotating. A fixed duty cycle control signal is added to the control signal for the field excitation current only when a serious fault is detected, thus limiting battery drain and excessive temperature in the regulator module but not shutting the whole system down. The system thus provides the desirable "limp-home" capability.