Motorola Corporation

Wilson D Pace

Robert B Jarrett

David L Cave

William F Davis

David B Bell

Robert G Uskali

Howard F Weber

An electronic device (100) is disclosed including an electroluminescent (EL) backlight panel (140) and an EL driver circuit (210). The EL driver circuit (210) provides power to the EL backlight (140), as well as panel aging compensation and user adjustment capabilities. The EL driver circuit (210) is low-cost, small-size, and designed in such a way to be easily integrated into a custom integrated circuit. A method is provided for controlling and converting power to the EL backlight panel (140).

Driver circuit for electroluminescent panel

A power supply control integrated circuit includes an internal start circuit. The start circuit monitors the time that an output of a latch is in a first logic state such that after a predetermined length of time has elapsed the start circuit forces a second logic state to occur at the output of the latch.

Start circuit for a power supply control integrated circuit

A capacitance multiplier circuit is disclosed which is fabricated using integrated circuit techniques comprising an inverted multiple collector transistor structure wherein a first one of the multiple collectors is electrically shorted to the base of the transistor to form a current mirror. The collector areas between the first collector and a second one of the multiple collectors are area ratioed to provide a multiplication factor, which is determined by the ratio between the areas of the two collector regions. The capacitance value formed between the junction of the base and the second collector regions is multiplied by this multiplication factor to produce an effective capacitance at the second collector. The multiplication factor is independent to process and temperature variations.

Capacitance multiplier circuit

A sample and hold circuit for an automotive speed control system is disclosed which includes a non-monotonic digital-to-analog converter suitable for fabrication as a highly dense monolithic circuit. The non-monotonic digital-to-analog converter precludes the occurrence of large positive errors in the analog output value, which might be caused by tolerance errors in the ratio of binary-weighted currents within the digital-to-analog converter, by including offsetting negative errors within the design of the digital-to-analog converter.

Digital sample and hold circuit

Structure fabricating using standard integrated injection logic (I.sup.2 L) process techniques for providing a multiple of controlled current source outputs for driving I.sup.2 L to analog interfaces. The current source structure is formed in minimum die area because of the space saving features of I.sup.2 L and tracks the performance of the I.sup.2 L circuit. The current source includes a common P-type emitter region diffused into an isolated N-type epitaxial layer which has been isolated by a deep N+-type diffusion region. Multiple collector P-type regions which are isolated from each other by the N+-type isolating region are diffused into the isolated portion of the epitaxial layer in spaced relationship to the common emitter region. An ion implanted resistor couples the common emitter region to a source of operating potential such that current is injected from the emitter region via the lateral PNP formed transistors to produce multiple output currents from the collector regions. The collector regions are connected using conductive interconnects to respective I.sup.2 L to analog interfaces to provide current for operation of both the open collector I.sup.2 L gates and the analog devices.

Controlled current source for I.sup.2 L to analog interfaces

A differential to single-ended converter circuit is disclosed which utilizes integrated injection logic device geometrics to significantly reduce the area required to fabricate the converter within an integrated circuit. Inverted transistor operation and multiple collector output terminals allow the converter circuit to directly drive integrated injection logic circuitry which may be fabricated within the same integrated circuit chip. When used in conjunction with a voltage comparator circuit, the differential to single-ended converter circuit maintains the offset associated with the comparator circuit at a minimum despite variations in operating temperature and variations in integrated circuit processing.

Differential to single-ended converter utilizing inverted transistors

A current supply circuit is disclosed having a field effect transistor and negative feedback for degenerating the magnitude of the current supplied thereby. The negative feedback can be provided by a diffused resistor connected between the gate and source electrodes of the current supply field effect transistor. A differential amplifier which includes a pair of differentially coupled amplifying field effect transistors is coupled to the current supply circuit. The negative feedback enables the current supply device to provide a current which compensates the differentially coupled field effect transistors over processing while not deleteriously affecting the temperature characteristics thereof. A bipolar diode and a bipolar transistor can be included in the current supply for enabling the resistor to take up less chip area and for allowing more flexibility in the design of the geometry of the current supply, field effect transistor.

Field effect transistor current source

An interface circuit is disclosed for receiving a ground-referenced A.C. signal for detecting transitions of the A.C. signal about ground potential. An input transistor is enabled when the A.C. signal voltage falls below ground potential by one base-emitter forward drop. The input transistor is disabled when the A.C. signal voltage rises above ground potential by one base-emitter forward drop. A feedback circuit and a bias circuit are coupled to the input transistor for switching the threshold levels of the input transistor. The interface circuit employs a hysteresis-type switching action for improving noise immunity while providing a symmetric output waveform. The circuit requires only a single power supply and is suitable for fabrication as a highly dense, monolithic integrated circuit. Also, the circuit provides a low input impedance to large positive and negative voltage transients.

Comparator with hysteresis for interfacing with a ground-referenced A.C.

An amplifier circuit is disclosed which includes a current supply circuit having a field effect transistor and negative feedback for degenerating the magnitude of the current supplied thereby. The negative feedback can be provided by a diffused resistor connected between the gate and source electrodes of the current supply field effect transistor. A differential amplifier which includes a pair of differentially coupled amplifying field effect transistors is coupled to the current supply circuit. The negative feedback enables the current supply device to provide a current which compensates the differentially coupled field effect transistors over processing while not deleteriously affecting the temperature characteristics thereof. A bipolar diode and a bipolar transistor can be included in the current supply for enabling the resistor to take up less chip area and for allowing more flexibility in the design of the geometry of the current supply, field effect transistor.

Differential field effect transistor amplifier having a compensating

An integrated circuit in which the Hall-Effect device and the sensing circuit can be incorporated on a single monolithic chip includes a Hall-Effect generator responsive to a magnetic flux change for generating a Hall-Effect voltage. A differential amplifier and current mirror circuit are coupled to the Hall-Effect device in order to vary or track the threshold voltage of the differential amplifier circuit in accordance with the output voltage from the Hall-Effect device irrespective of current changes in the Hall-Effect device due to temperature variations.

Hall-effect integrated circuit switch

A cruise control system having means to provide a signal corresponding to a desired speed for use by a servo control to regulate the speed. This system uses a current source to ramp charge a first capacitor. A comparator compares magnitude of the voltage on the first capacitor against the signal representative of the desired speed. A first counter is used to accumulate counts from a first frequency generator. A latch counter capable of following the counts in the first counter is used to store the counts when the comparator indicates the voltage on the first capacitor is substantially equal to the magnitude of the signal representative of the speed. A digital comparator then compares the counts stored in the latch counter against counts being accumulated anew in the first counter while the first capacitor is being recharged. Means are provided to inhibit the first capacitor from being charged further after the digital comparator indicates equality between the quantity of the counts being compared. Means to transfer the voltage on the first capacitor to a second capacitor are used so that the voltage on the second capacitor can be compared against the signal representative of the actual speed which then provides an output to the servo control to regulate the speed.

Cruise control method and apparatus

In an electronic ignition system for controlling engine spark and firing thereof, a circuit is provided for causing the current through the ignition coil to have a greater value during starting of the engine than the current therethrough when the engine is running normally. The circuit is operated in conjunction with control of a current interrupt circuit of the ignition system. Moreover, the start-to-run circuit prevents premature engine spark, which might otherwise occur if the ignition system is switched from a start mode to a run mode just prior to desired engine firing, by controlling the transition time of the current through the coil from the start value to run value.

Start-to-run circuit for an electronic ignition system

A bilateral zener diode is described having improved terminal characteristics including a low noise factor, a predictable breakdown voltage level in the reverse breakdown mode within plus or minus 3 percent, and providing a sharp reference voltage which is substantially independent of diode current. This bilateral conducting diode is achieved by utilizing a collector ring diffusion of the same conductivity type as the anode diffusion, but spaced from both the anode diffusion and the cathode diffusion. In the forward bias conduction mode, the flow of current from the anode to the cathode is collected by the collector ring and returned to the cathode providing a forward transfer efficiency which is typically 90 percent.

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Tempe, AZ, United States of America

Wilson D Pace