Abstract: A power output stage has a Darlington-pair circuit (11, 12) for switching an inductive load, especially the ignition coil of an internalcombustion engine. In order to predetermine the operating mode of the power output stage, a switch (24) is provided which bridges the base-emitter junction of the Darlington-pair circuit (11, 12), is closed in the event of a quick disconnection of the output stage, and is opened in the event of a voltage-limited disconnection of the output stage. A voltage divider, which consists of at least two resistors (16, 18) and bridges the switching junction of the Darlington-pair circuit (11, 12), is connected by means of its pick-off to the junction point between the switch (24) and the base of the Darlington-pair circuit (11, 12), the switch (24) being connected in parallel with a part (18) of the voltage divider.

Abstract: An integrated anode power stage using one or more Darlington transistors combinations is constituted for currents exceeding 5 amperes and voltages exceeding 200 volts. On a common semiconductor substrate there are provided, in addition to the Darlington circuit or circuits a large number of peripheral components, both active and passive, such as are required for protection, regulation and turning on or off of the final stage for operating an ignition coil in a motor vehicle. By providing these components in basins of the same conductivity type as the base of the power transistor a unit is provided that is economical to make as well as compact and reliable.

Abstract: A capacitor which is charged by recurring square waves of a normally functioning microprocessor discharges at a steady rate, so that if the square waves do not continue, an operational amplifier will switch over and produce a reset pulse for the microprocessor. Repeated transitions of one polarity of the square wave recharge the capacitor during a short interval terminated by a second operational amplifier when the capacitor reaches a fixed level of charge. This second amplifier, which has feedback coupling, also initiates the timing discharge of the capacitor. A diode network at its output prevents charging the capacitor in the static state. This arrangement makes it unnecessary to provide another capacitor for quickly recharging the capacitor to prevent its discharge from switching over the first-mentioned operational amplifier.

Abstract: A timing wave generator 26 provides the same input to two threshold switches that switch on at approximately the same time but have different switching hysteresis. The switch with the smaller hysteresis can affect ignition timing only through a delay circuit while the other can do so directly. If the engine stalls the delay circuit will assure that the primary current is shut off in a short time. In normal operation the large hysteresis of one of the threshold switches is in control and provides insensitivity to disturbance, but during startup the characteristics of the delay circuit can provide the appropriate ignition timing.

Abstract: An overvoltage protection circuit is galvanically, directly connected across at least part of the secondary winding in the ignition system of an internal combustion engine. The input portion of the overvoltage protection circuit is a voltage divider preferably constituted by RC elements. The voltage at the tap of the voltage divider is applied to a Schmitt trigger. When the voltage across the secondary winding becomes excessively high, the Schmitt trigger output pulse triggers a monostable multivibrator whose output pulse in turn increases the conductivity of a transistor switch located in series with the primary. The increase in primary current tends to oppose further increases in primary and secondary voltages. Alternatively, the output from the multivibrator could be used to shorten the time of current flow in the primary winding in subsequent ignition time intervals or to completely block any subsequent ignition process.

Abstract: To provide a composite output pulse in which the pulse length increases relative to the angle of rotation as the speed of a rotating element, typically a rotor coupled to an internal combustion engine increases so that the closing angle of current supply to an ignition coil increases with speed, a magnetic element or other marker on a rotor is exposed to two transducers, one of which provide a signal which is position dependent and the other one a signal which is speed dependent. The output signals from the transducers are combined. The position dependent transducer provides an output pulse of fixed pulse length, relative to angle of rotation of the rotating element, the speed dependent pulse providing output pulses of variable pulse length which overlap with the pulse of fixed pulse length.

Abstract: In order to increase the closure angle of an interrupter switch connected in series with the primary winding of an ignition coil with increasing engine speeds, a capacitor is connected to the input of a trigger circuit whose output controls this closure angle. The capacitor is charged through a diode while the trigger circuit is switched out. The voltage across the capacitor shifts the threshold of the trigger circuit in a direction increasing the time that the interrupter switch is conductive. The charge on the capacitor is controlled by a signal generator which furnishes an output signal having an amplitude increasing with increasing engine speeds. The closure angle of the interrupter switch therefore also varies as a function of engine speed.

Abstract: When the engine accelerates, the angle over which the ignition switch is closed prior to initiating the spark is automatically increased. Acceleration of the engine is detected by a comparator which compares the value of a speed-dependent signal in sequential cycles and initiate closure of the ignition switch if a predetermined difference is exceeded between the so-compared signals at a predetermined time in the cycle. Under static or decelerating conditions, the speed-dependent signal is compared, in each cycle, to the output of an integrator circuit. The integrator circuit integrates in a first direction at a first rate up to the above-mentioned predetermined time in the cycle and in the opposite direction at a second predetermined rate for the remainder of the cycle. The average value of the integrator output signal corresponds to the engine speed. When the so-compared signals are equal, the second comparator furnishes an output signal which closes the ignition switch.

Abstract: The voltage across a capacitor is changed in a first direction while the current in the primary winding of the ignition coil increases to a predetermined value less than the value required for ignition and is thereafter changed in a second direction until ignition takes place. The voltage across the capacitor is applied to the inverting input of a difference amplifier constituting a threshold stage controlling the initiation and termination of current flow through the ignition coil. The two changes are symmetrical when the engine speed remains constant. The residual voltage across the capacitor at the end of the second change is maintained until the start of the next subsequent first change, so that the time at which the threshold stage switches in, that is the time at which primary current starts to flow in the ignition coil changes as a function of the residual voltage in the capacitor.

Abstract: To operate an ignition control transistor, connected into the primary ignition coil under minimum saturation condition regardless of voltage level of the supply voltage, delivered, for example, from the battery of an automotive vehicle, at least one timing circuit is connected to the voltage supply to have a timing interval which varies as a function of supply voltage, the timing interval controlling the duration of current flow through the transistor as a function of supply voltage so that the transistor will be conductive for the required time to store magnetic energy in the coil, though not for an excessively long period of time regardless of the level of supply voltage within the limits normally experienced in automotive ignition systems.

Abstract: The primary of the ignition coil is tapped to provide two partial primary portions which are serially connected; during an initial current flow, only one partial portion has current flowing therethrough, the other partial portion being short-circuited. When the current through the coil has risen to a predetermined level, as sensed by current flow through a sensing resistor, the short circuit across the second partial portion is removed so that current can continue to flow through the entire primary, causing a substantial drop in current level but maintaining the stored inductive energy. Current can thus rise rapidly initially, so that the coil will store sufficient energy to initiate sparking at high speeds of the connected internal combustion engine while, at low speeds thereof, the overall current flow through the coil is decreased.

Abstract: To provide a first accurately timed ignition impulse for any one ignition event, and then, selectively, one or more ignition pulses, in accordance with sensed or existing operating parameters of the engine, a first ignition pulse is generated, accurately, in accordance with timing as determined by an ignition timing stage; a frequency generator is selectively enabled upon the presence or absence of operating parameters at certain values to provide sequential ignition pulses after the first, accurately timed ignition pulse has been provided.

Abstract: To improve the operation of semiconductor control ignition systems under widely varying supply voltage conditions, a voltage divider having a division tap point is connected in parallel to the main switching part of the switching transistor of the ignition system, and a voltage breakdown element, typically a Zener diode is connected from the tap point to the control electrodes of the semiconductor switch to provide an additional control voltage thereto if the voltage at the tap point exceeds a value leading to breakdown of the breakdown device (Zener diode); the main control circuit for the main ignition transistor may be conventional.