# US 4,259,939 A · Four lead monolithic Darlingtons

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- Number: US 4,259,939 A
- Document ID: US4259939A
- Status: Granted
- Kind: A
- Application number: 06/076,567
- Filed: 1979-09-18
- Granted: 1981-04-07
- Earliest claimed: 1978-10-02
- Assignees: Lumenition Limited
- Inventors: John P. Coates
- Web page: https://patentgrep.com/patent/US4259939A

## CPC

- F02P 3/0435: {with semiconductor devices (F02P3/0453, F02P3/051, F02P3/0552 take precedence)}
- F02P 3/0552: {Opening or closing the primary coil circuit with semiconductor devices}
- F02P 7/073: Optical pick-up devices
- H03K 17/04213: {in bipolar transistor switches}
- H03K 17/08146: {in bipolar transistor switches}
- H03K 17/7955: {using phototransistors}
- H10D 84/642: {Combinations of non-inverted vertical BJTs of the same conductivity type having different characteristics, e.g. Darlington transistors}
- H10W 72/5445: {being orthogonal to a side surface of the chip, e.g. parallel arrangements}
- F02P: IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES ({anti-pollution means for internal-combustion engines F02B17/00}; specially adapted for rotary-piston or oscillating-piston engines F02B53/12; {ignition of gas turbine plants F02C7/26; ignition of jet propulsion plants F02K9/95; starting of combustion engines F02N9/00}; ignition of combustion apparatus in general, glowing plugs F23Q; measuring of physical variables in general G01; controlling in general G05; data processing in general G06; electrical components in general see Section H; {ignition coils H01F38/12}; sparking plugs H01T13/00)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10

## Abstract

A monolithic Darlington in which the transistors forming the Darlington pair are formed on a substrate together with a fourth terminal in addition to the normal three terminals provided for a Darlington pair, the fourth terminal being connected to the base electrode of the second transistor and the emitter electrode of the first transistor. The addition of the fourth terminal enables a control circuit for controlling the rate of switch off to be connected between the fourth terminal and the command collector electrode, this removing the effect which the stored charge on the base electrode of the first transistor has on the switching rate of the Darlington pair, thus enabling a faster switching rate to be achieved.

## Claims

### Claim 1

The combination of a monolithic Darlington and a control circuit for controlling the rate at which the monolithic Darlington is permitted to switch off; said monolithic Darlington comprising first and second transistors connected so that the collectors thereof are common and the emitter of the first transistor is connected to the base of the second transistor forming an intermediate emitter-base junction therebetween, and said combination including four terminals formed on a silicon wafer and interconnected such that a first terminal is connected to the common collectors, a second terminal is connected to the base of the first transistor, a third terminal is connected to the emitter of the second transistor, and the fourth terminal is connected to the intermediate emitter-base junction of the two transistors; said control circuit being connected between the first terminal and the fourth terminal.

### Claim 2 (depends on 1)

The combination according to claim 1, wherein said control circuit comprises at least one zener diode, a capacitor connected in parallel with the zener diode, and a resistor connected in series with the parallel combination of the zener diode and the capacitor.

### Claim 3 (depends on 2)

An opto-electronic ignition system incorporating the combination according to claim 2, wherein said monolithic Darlington forms the final stage of a series of inverse switching Darlington pairs in a transistor chain, said combination being connected in series with the primary winding of an ignition coil.