GB2194108A - Circuit arrangement with a microprocessor - Google Patents
Circuit arrangement with a microprocessor Download PDFInfo
- Publication number
- GB2194108A GB2194108A GB08713521A GB8713521A GB2194108A GB 2194108 A GB2194108 A GB 2194108A GB 08713521 A GB08713521 A GB 08713521A GB 8713521 A GB8713521 A GB 8713521A GB 2194108 A GB2194108 A GB 2194108A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit
- microprocessor
- switching transistor
- short
- circuit arrangement
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/08—Modifications for protecting switching circuit against overcurrent or overvoltage
- H03K17/082—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit
- H03K17/0826—Modifications for protecting switching circuit against overcurrent or overvoltage by feedback from the output to the control circuit in bipolar transistor switches
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
- H03K17/62—Switching arrangements with several input- output-terminals, e.g. multiplexers, distributors
- H03K17/6271—Switching arrangements with several input- output-terminals, e.g. multiplexers, distributors with several outputs only and without selecting means
Abstract
The invention relates to a microprocessor set-up. A set-up, including a microprocessor 1 and a reset circuit 2, controls at least one output stage T1, S 9, 10 including a switching transistor T1. In order, by simple means, to avoid the destruction of the switching transistor T1 in the event of a short-circuit, a threshold-activated interrupter R2, T2 is coupled up to the switching transistor T1. The latter reacts in the event of a short-circuit, so that the reset circuit 2 resets the microprocessor 1 in such a way that the switching transistor T1 is blocked. <IMAGE>
Description
SPECIFICATION
Circuit arrangement with a microprocessor
The invention relates to a circuit arrangement, in which a microprocessor comprising a reset circuit controis at least one output stage, which comprises a switching transistor, whereof the collector-emitter section can be connected by way of a terminal strip in series to a load switching relay.
In circuit arrangements of this type, the terminal strip is open at the time of assembly and in cases of maintenance. In the case of measuring or maintenance work the danger then exists that a short-circuit occurs at the terminal strip due to tools. This short-circuit destroys the switching transistor of the output stage.
Destruction of the switching transistor could easily be avoided by a short-circuit proof construction of the output stage. However, a circuit of this type would be expensive. Moreover, if several output stages are provided, it would have to be provided in each output stage.
It is the object of the invention to propose a circuit-arrangement of the afore-mentioned type, in which in the case of a short-circuit at the terminal strip, destruction of the switching transistor is prevented with simple means.
According to the invention, the above object is achieved in a circuit arrangement of the afore-mentioned type due to the fact that a threshold value switch is associated with the switching transistor, which switch responds in the case of a short-circuit at the terminal strip and that the threshold value switch is connected to the reset circuit so that in the case of a short-circuit the latter resets the microprocessor, due to which the latter blocks the switching transistor of the output stage.
This construction of the circuit involves only low expenditure, because the microprocessor which is provided anyhow is used with the reset circuit for disconnecting the switching transistor in the case of a short-circuit. Due to this it readily happens that the output stage goes back into operation after eliminating the short-circuit.
In a preferred embodiment of the invention, a resistor is connected in series with the switching transistor of the output stage, with which resistor the threshold value switch is connected in parallel. In the case of a shortcircuit at the terminal strip, the current flowing through the resistor increases in a corresponding manner. The voltage then occurring at the resistor leads to the response of the threshold value switch.
In a development of the invention, in a circuit arrangement with several output stages, a common resistor is connected in series with the switching transistors of the output stages, which resistor is connected in parallel with the threshold value switch. It is thus superfluous to provide individual means for preventing a short-circuit for each output stage. The microprocessor is always reset if a short-circuit occurs at the connecting terminals of one of the output stages.
Further advantageous developments of the invention will become apparent from the following description of one embodiment. The drawing shows its wiring diagram.
A reset circuit 2 is connected in series with a microprocessor 1. In the case of this example, two output stages are connected to the microprocessor 1.
Each output stage comprises a transistor
T1, whereof the base is connected to the microprocessor 1 respectively by way of a limiting resistor R1. The collector-emitter sections of the transistor T1 lie parallel to each other.
The emitters are connected to the poles (3 or 4) of a terminal strip 5. Opposite poles (6 or 7) of the terminal strip 5 are connected to the negative pole 8 of a current supply. A diode D1 is respectively connected parallel to the poles 3, 6 or 4, 7.
Load switching relays 9, 10 are connected to the pole 3, 6 and the pole 4, 7. The latter switch units of an electrical household appliance, for example of a microwave oven.
Connected to the collectors of the transistors T1 is a common resistor R2, which has a load-impedence resistance value of for example 22 Ohms. The resistor R2 is connected to the positive pole 11 of the current supply.
Connected parallel to the resistor R2 is the emitter-base section of a transistor T2, whereof the base is connected in series with a resistor H3. The collector of the transistor T2 is connected to the reset circuit 2.
In normal operation of the circuit, the resistor R2 and the transistor T2 have no influence on the operation of the circuit arrangement.
The load switching relays 9, 10 are actuated in a desired manner by the microprocessor 1.
If the load switching relays 9, 10 are disconnected from the terminal strip 5 for assembly or measuring purposes, then the pole 3, 6 or the pole 4, 7 is not precluded from being accidentially bridged, so that a shortcircuit results. In the case of a short-circuit, the current through the resistor R2 is increased irrespective of which pole 3 or 4 is short-circuited by the opposing pole 6 or 7, so that the voltage dropping at the resistor increases in a corresponding manner. It then connects the transistor T2 through. Due to this the reset circuit 2 resets the microprocessor 1 so that its outputs have high impedence. The transistors T1 block. Due to this the short-circuit current is interrupted. Since the short-circuit current is only present for a few 10-6 secs, there is no danger that the transistors T1 are destroyed. The outputs of the microprocessor 1 are protected by the limiting resistors R1 in the case of a short circuit.
During the sequence of operations of the microprocessor 1, the transistors T1 are always blocked as long as there is a short circuit between the poles (3 or 4 and 6 or 7).
After eliminating the short-circuit, the output stages are connected without further measures in the programme provided.
Claims (5)
1. Circuit arrangement, in which a microprocessor having a reset circuit controls at least one output stage, which comprises a switching transistor, whereof the collectoremitter section can be connected by way of a terminal strip in series to a load switching relay, characterised in that associated with the switching transistor (T1) is a threshold value switch (R2, T2), which responds in the case of a short-circuit at the terminal strip (5) and that the threshold value switch (R2, T2) is connected to the reset circuit (2) so that the latter resets the microprocessor (1) in the case of a short-circuit, due to which the latter blocks the switching transistor (T1) of the output stage.
2. Circuit arrangement according to Claim 1, characterised in that a resistor (R2) of the threshold value switch (R2, T2) is connected in series with the collector-emitter section of the switching transistor (T1) of the output stage.
3. Circuit arrangement according to Claim 2, characterised in that connected in parallel with the resistor (R2) is the base-emitter section of a transistor (T2), whereof the collector is connected to the reset circuit (2).
4. Circuit arrangement according to one of the preceding Claims with several parallel output stages, characterised in that a common resistor (R2) is connected in series with the switching transistors (T1) of the output stages.
5. Circuit arrangement substantially as hereinbefore described with reference to the accompanying drawing.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19863621375 DE3621375A1 (en) | 1986-06-26 | 1986-06-26 | CIRCUIT ARRANGEMENT WITH A MICROPROCESSOR |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8713521D0 GB8713521D0 (en) | 1987-07-15 |
| GB2194108A true GB2194108A (en) | 1988-02-24 |
| GB2194108B GB2194108B (en) | 1990-04-04 |
Family
ID=6303726
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8713521A Expired - Fee Related GB2194108B (en) | 1986-06-26 | 1987-06-10 | Circuit arrangement with a microprocessor |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE3621375A1 (en) |
| FR (1) | FR2600845A1 (en) |
| GB (1) | GB2194108B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2200002A (en) * | 1986-12-23 | 1988-07-20 | Qualter Hall & Co Limited | Microprocessor-based controller especially for hazardous environment |
| EP0410188A2 (en) * | 1989-07-27 | 1991-01-30 | TEMIC TELEFUNKEN microelectronic GmbH | Circuit arrangement for protecting a clocked semi-conductor switch |
| US5487013A (en) * | 1991-06-13 | 1996-01-23 | Siemens Aktiengesellschaft | System and method for reading operating parameters into an operationally ready proximity switch |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3028371B2 (en) * | 1989-08-22 | 2000-04-04 | ヴアブコ・ヴエステイングハウス・フアールツオイクブレムゼン・ゲゼルシヤフト・ミツト・ベシユレンクテル・ハフツング | Power transistor and load monitoring method controlled by the power transistor |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4574266A (en) * | 1983-06-13 | 1986-03-04 | Motorola, Inc. | Electrical load monitoring system and method |
| DE3338764A1 (en) * | 1983-10-26 | 1985-05-09 | Robert Bosch Gmbh, 7000 Stuttgart | Circuit arrangement for switching electrical loads on and off and monitoring them |
-
1986
- 1986-06-26 DE DE19863621375 patent/DE3621375A1/en not_active Withdrawn
-
1987
- 1987-06-10 GB GB8713521A patent/GB2194108B/en not_active Expired - Fee Related
- 1987-06-19 FR FR8708602A patent/FR2600845A1/en not_active Withdrawn
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2200002A (en) * | 1986-12-23 | 1988-07-20 | Qualter Hall & Co Limited | Microprocessor-based controller especially for hazardous environment |
| GB2200002B (en) * | 1986-12-23 | 1991-09-11 | Qualter Hall & Co Limited | Microprocessor-based controllers especially for hazardous environment |
| EP0410188A2 (en) * | 1989-07-27 | 1991-01-30 | TEMIC TELEFUNKEN microelectronic GmbH | Circuit arrangement for protecting a clocked semi-conductor switch |
| EP0410188A3 (en) * | 1989-07-27 | 1991-07-31 | Telefunken Electronic Gmbh | Circuit arrangement for protecting a clocked semi-conductor switch |
| US5487013A (en) * | 1991-06-13 | 1996-01-23 | Siemens Aktiengesellschaft | System and method for reading operating parameters into an operationally ready proximity switch |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2600845A1 (en) | 1987-12-31 |
| GB2194108B (en) | 1990-04-04 |
| DE3621375A1 (en) | 1988-01-14 |
| GB8713521D0 (en) | 1987-07-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19920610 |