DE102004031722A1 - Circuit arrangement, has temperature controlled switch unit that switches from on state to off state when selected temperature threshold is reached, where unit is integrated into enclosure and interconnected with semiconductor switch - Google Patents

Abstract

circuitry with at least one load path (7) comprising a series circuit with a voltage source (1) for providing a supply potential (+ U), a semiconductor module, a semiconductor module upstream Current fuse (2), which is suitable, the current flow in the series circuit upon reaching a selectable Current threshold value, and at least one load resistor (4), wherein the semiconductor module comprises a housing (18) and at least one in the case (18) arranged controllable semiconductor switch (3), the through its supply voltage connections to the voltage source is connected and with a loadable control unit mass (9) is electrically conductively connected, wherein in the housing (18) a temperature-controlled switching element (8) is integrated, the to the supply potential (+ U) and to the control unit ground (9) is connected, wherein the temperature-controlled switching element (8) is suitable, with an increase in temperature upon reaching a selectable temperature threshold from a high-impedance, essentially power-saving off-state into a low-impedance, current-permeable on-state, causing an electrically conductive connection from the voltage source (1) to the control unit mass (9) whose electrical resistance is a current with a current strength of at least the current threshold value of the current fuse (2) allows.

Description

The The present invention relates to a circuit arrangement with at least a load path connected in series to a voltage source, a semiconductor module with at least one controllable semiconductor switch, an upstream of the semiconductor module power fuse, and at least includes a load resistor.

Become controllable semiconductor switches outside their specification operated, this can lead to melt through, i. to a so-called Lead through the semiconductor switch. This typically arises a non-controllable conductive Channel, which carries electricity continuously. As a result, will at a high-side semiconductor switch connected upstream of a load resistor a short circuit between the supply potential and the output terminal of the semiconductor switch, while at a load resistance downstream low-side semiconductor switch a short circuit of the Output terminal of the semiconductor switch to the load mass causes becomes.

reason for the By alloying a semiconductor switch, for example, is one way called "load-dump" effect, which can occur when a voltage source coming from a generator is charged inadvertently, for example by a loose connection, disconnected from the generator which can lead to voltage spikes on the semiconductor switch. Another, not always excluded cause of the Ignorance based, improper use of the semiconductor switch through the user outside its specification.

Next the concomitant loss of function are all alloyed areas In semiconductor switches to be considered as particularly dangerous, since they usually have a much higher have electrical resistance as a non-alloyed semiconductor switch. While a full power MOSFET will only have one on-resistance typically about 10 mΩ, is at an alloyed area with an electrical resistance in the order of typically about 1 Ω too expected. The high electrical resistance of an alloyed area causes causes while the operation thus a very high power dissipation at the semiconductor switch, causing a temperature increase and finally can lead to a fire of the semiconductor switch or its surroundings. To make matters worse, that in such a malfunction of the Semiconductor switch a connected in the load path short-circuit protection the power line can not break because the current in the Load route opposite a "proper" amperage not elevated is.

In order to achieve an interruption of the load path through a short-circuit protection in a semiconductor semiconductor breaker, has already been proposed to provide a temperature sensor in close proximity to a semiconductor switch, which actuates a short-circuit switch for triggering the current fuse after successful detection of a selectable critical temperature. This solution is in 1 shown. According to 1 For example, a conventional circuit arrangement includes a battery 1 , a short-circuit protection 2 , a plurality of circuit breakers 3 , a plurality of the circuit breakers 3 downstream loads 4 , as well as a short-circuit switch 5 , As usual in the automotive sector, the negative terminal is grounded. The short-circuit switch 5 and the circuit breakers 3 are in a common electronics housing 6 added. Every circuit breaker 3 is equipped with a temperature sensor (not shown) wel cher on reaching a temperature threshold, the short-circuit switch 5 closes, so that the current fuse 2 the current flow in the load path 7 interrupts.

adversely in the above solution First of all, that is usually a plurality of semiconductor switches on a single board are built so that, due to poor thermal conductivity and avoidance insufficient response of the temperature sensor, in Generally for each semiconductor switch provided a separate temperature sensor must become. Besides the problems with the practical implementation this leads also at high costs.

In contrast there is the object of the present invention is a circuit arrangement indicate with a controllable semiconductor switch in a load path, through which in more reliable Way a power interruption in an overheating of the semiconductor switch, for example, as a result of a Durchlegierens can be achieved. Such Circuit arrangement is intended with regard to mass production in simple and inexpensive way be produced.

These Task is according to the proposal of the invention by a circuit arrangement with the characteristics of the independent Claim solved. advantageous Embodiments of the invention are indicated by the features of the dependent claims.

According to the invention, a circuit arrangement with at least one load path is shown, which is a series circuit with a voltage source for providing a supply potential, a semiconductor module with at least one controllable semiconductor switch, a semiconductor module upstream current fuse, which is suitable for the current flow in the load path upon reaching a selectable current threshold value interrupt, and at least one load resistor comprises. Such a current fuse may be formed as a conventional short-circuit fuse in which, for example, melts a fuse wire upon reaching a critical current. The semiconductor module is also provided with a housing in which the controllable semiconductor switch is housed. The controllable semiconductor switch is connected with its two supply voltage terminals to the voltage source and further electrically connected to a control unit ground. The ECU ground is the mass connection of the control logic, which is commonly referred to as "logic ground". In contrast to a conventionally used control device mass, which must carry only much lower control currents compared to typical load currents in the ampere range, the control unit mass of the circuit arrangement of the present invention is designed as a loadable, ie powerful control device mass. As a result, the control unit mass in the circuit arrangement of the present invention is generally to be provided with thicker connection lines in comparison with a conventional control unit ground. While in a conventional control unit ground approximately in the area Atuomotive connecting lines are used, which have a typical cross-sectional area from about 0.5 mm ² , the leads of the control unit mass of the circuit arrangement according to the invention preferably have a larger cross-sectional area in the range of at least about 1 to about 2 mm ² , adapted to the dimensioning of the current fuse.

at the circuit arrangement according to the invention is in the case In addition, a temperature-controlled switching element integrated, i. in the housing integrated with one of its supply connections to the Supply potential of the voltage source is connected while it with the other of its supply connections to the ECU ground connected. In this respect, the temperature-controlled switching element causes in the on state an electrically conductive connection between the supply potential and the ECU ground connection such that the controllable semiconductor switch is short-circuited.

The Temperature controlled switching element is suitable with increasing Temperature when reaching a selectable Temperature threshold of a high-impedance, current substantially blocking off-state, into a low-resistance, current-passing To switch on state. Will the temperature-controlled switching element is switched to its on state, therefore, a current path of the voltage source is formed to the control unit mass. Essential Here it is that the electrical resistance of this current path is so low is that a current in the current path is allowed with a current whose value corresponds at least to the current threshold value of the current fuse, so that trigger the current fuse can.

Further is in the circuit arrangement according to the invention the "load capacity" of the control unit mass be designed so that the control unit mass through the current path at least between load source and controller mass flowing load current at least can carry until the current fuse triggers, in general, above the current threshold of the current fuse, a comparatively higher current through the temperature-controlled switching element to a faster triggering of Current fuse leads. In this case, it may be advantageous if, in the case of a passage switched on Temperature controlled switching element of the voltage source current flowing to the control unit ground at least one size of that about 2 times until which has about 3 times the current threshold value of the current fuse. moreover is the temperature controlled switching element designed so that a any heating, at least as long as it does not lead to its destruction, until the current fuse triggers.

at an advantageous embodiment of the circuit arrangement according to the invention can the semiconductor switch and the temperature-controlled switching element be executed as two separate chips. Such a design may, for example, in a chip-on-chip structure or a chip-by-chip structure can be realized. In the former Case the two chips are arranged one above the other, while in the latter case, the two chips are arranged side by side are. In the latter case, it is advantageous if the two Chips are applied on a common lead frame.

For the function of the temperature-controlled switching element, it is important that this is arranged in spatial proximity to the semiconductor switch, so that there is a thermal connection of the temperature-controlled switching element to the semiconductor switch and a rapid response of the temperature-controlled switching element is ensured at an overheating of the semiconductor switch. Since the semiconductor switch and the temperature-controlled switching element within a housing inte When the semiconductor switch and the temperature-controlled switching element are realized as two separate chips, the above assumption is satisfied in general.

at an alternative embodiment the circuit arrangement according to the invention are the semiconductor switch and the temperature-controlled switching element integrated monolithically within a chip. Such a realization is on the one hand advantageous in terms of manufacturing technology, and On the other hand, it provides an excellent thermal connection of the Temperature controlled switching element to the semiconductor switch safely.

If the semiconductor switch and the temperature-controlled switching element Within a chip are monolithically integrated, it is extremely advantageous if the two elements are nested, i. if at a usual one Cell structure of semiconductor switch and temperature-controlled switching element, the cells of the semiconductor switch and the cells of the temperature-controlled Switching element are interleaved. Crucial here is in that the interleaving of the semiconductor switch and the temperature-controlled switching element of the semiconductor switch occupies a comparatively larger chip area and for the heat dissipation a larger chip area than heat sink to disposal stands. Insofar occurs at a same power loss at a Semiconductor switch with a comparatively larger chip area a comparatively lower temperature increase on. Such a design thus has the significant advantage that for the semiconductor switch a larger heat sink to disposal stands, so that serious overheating damage, such as For example, a fire of the chip or board can be avoided can. The cells of semiconductor switch and the temperature controlled Switching element can here beispielseise in the form of strips or blocks into each other be nested.

at a further advantageous embodiment of the invention the semiconductor switch is a power semiconductor switch, in particular, a power MOSFET. The power semiconductor switch can be referred to as a so-called "smart" power semiconductor switch be formed, i. a power semiconductor switch, in addition to the switching function further protection and diagnostic functions are realized. Such smart circuit breakers are used by the Applicant, for example, under the trademarks "PROFET" or "HITFET" sold commercially. These circuit breakers are about having a protection function with respect to a voltage spike provided for that ensures that an overvoltage occurs is clamped. Although this results in a breakdown in certain Cases avoided It has been shown that the energy intake of such Smart circuit breaker naturally limited according to is, allowing a breakdown of the smart circuit breaker when operating outside the specification is not excluded.

at a particularly advantageous embodiment of the temperature-controlled Switching element is a thyristor whose temperature-dependent switching behavior is exploited. It may be advantageous if the semiconductor switch and the thyristor in the form of a lateral thyristor within a Chips are monolithically integrated.

It is according to the invention furthermore advantageous if the temperature-controlled switching element with increasing temperature at a threshold temperature in the range of about 250 ° C up to 350 ° C from its off state to its on state. With others Words, the temperature-controlled switching element is located below the threshold temperature in its off state while it is above the Threshold temperature is in its on state and thus at a temperature increase upon reaching the threshold temperature from its off state to its On state switches. This ensures that a power interruption in the range of operating temperatures of semiconductor switches, which are usually up to 200 ° C avoided becomes; at the same time an early Response to overheating the switch ensured. The current threshold of the current fuse is typically in a range of a few amps to about 100 A. The supply voltage the voltage source, in particular in applications in the automotive sector, typically ranges from about 12V to about 42V.

In the circuit arrangement according to the invention The semiconductor switch can load the load in the form of a high-side switch upstream or downstream in the form of a low-side switch be.

The Invention will now be explained in more detail with reference to embodiments, wherein Reference to the attached Drawings is taken. In the figures are the same or the same acting elements with the same reference numerals.

1 shows a schematic representation of a conventional circuit arrangement with a plurality of circuit breakers for switching loads;

2 shows a circuit arrangement according to the invention;

3 shows an embodiment of the circuit breaker and the temperature-controlled switching element of Schaltungsa invention arrangement of 2 ;

4 shows an embodiment of a semiconductor switch and a temperature-controlled switching element of the circuit arrangement according to the invention, wherein semiconductor switch and temperature-controlled switching element are designed as two separate chips;

5A and 5B show a lateral thyristor, and a power MOSFET, which are monolithically integrated in a chip;

6A to 6C show schematically a non-interleaved or interleaved cell structure of a semiconductor switch and a temperature-controlled switching element of the circuit arrangement according to the invention.

1 which shows a circuit arrangement known in the prior art has already been explained above, so that a description can be omitted here.

2 shows a circuit arrangement according to the invention, in which a load path 7 a series connection of a battery 1 to provide a supply potential + U, a current fuse 2 for interrupting the current flow of the load path 7 upon reaching a selectable current threshold, a plurality of power MOSFETs 3 , which are connected in parallel to each other, and a plurality of loads to be switched 10 includes. Every power MOSFET 3 is in this case connected with its supply voltage terminals to the supply voltage and is further to a powerful, ie loadable, control device ground 9 connected. There is every power MOSFET 3 with an input line 11 through which control signals, which are usually generated by a control logic (not shown), to the power MOSFET 3 be transmitted. Via an output line 12 is every power MOSFET 3 with the load 4 connected, which in turn to a load mass 10 connected. Typically, the cathode is the battery 1 with the load mass 10 connected. Further, for each power MOSFET 3 a thyristor 8th provided as a temperature-controlled switching element, wherein the thyristor 8th on the one hand with the connection connected to the supply potential + U and with the one with the loadable control unit ground 9 connected connection of the power MOSFET 3 is electrically connected. The thyristor 8th and the power MOSFET 3 are integrated in a housing (not shown).

For use as a temperature controlled switching element, the typical temperature / conductivity behavior of the thyristor 8th exploited. Consequently, the conductivity of the thyristor 8th not only dependent on the applied voltage, but also of its temperature, which is known to those skilled in that the ignition voltage of a thyristor decreases with temperature increase. The thyristor 8th is configured to ignite at a supply potential + U upon reaching a desired temperature threshold, which may be, for example, in the range of 250 ° C to about 350 ° C. Has the thyristor 8th ignited, then the circuit breaker 3 through the thyristor 8th shorted, causing a current path from the battery 1 to the loadable control unit mass 9 formed.

3 shows an embodiment of the power MOSFET 3 and the thyristor 8th the circuit arrangement of 2 , The power MOSFET 3 is here designed as a so-called smart circuit breaker, the circuit breaker by a control logic 15 and a control electrode 16 is controlled. The detailed presentation of 3 can be seen that the power MOSFET 3 over its drain connection 13 is connected to the supply potential + U, while its source terminal through the output line 12 is formed. The control unit of the power MOSFET 3 is also via a ground line 14 with the loadable mass 9 connected. The thyristor 8th is on the one hand via its anode connection 19 with the drain connection 13 of the power MOSFET 3 connected, and on the other hand via its cathode connection 20 to the ground line 14 the loadable control unit mass 9 connected. The power MOSFET 3 and the thyristor 8th are here in a housing 18 integrated monolithically.

4 shows an embodiment of the circuit arrangement according to the invention, in which a smart power MOSFET 3 and a thyristor 8th , which is composed of a sequence of doped layers with p-doping, n-doping, p-doping and n-doping, in a chip-by-chip arrangement next to each other on a lead frame 21 are arranged. The lead frame 21 is here with the supply potential + U via a connecting line 22 electrically connected.

In 5A and 5B an embodiment of the circuit arrangement according to the invention is shown, in which a Lateralthyristor and a power MOSFET in a chip, ie on a semiconductor substrate 31 are monolithically integrated. 5A shows the lateral transistor, while 5B shows a conventional power MOSFET, which on the right side or on the left side of the lateral thyristor of 5A to think about. In the semiconductor substrate is a n ⁺ -doped layer 23 formed on which an n-doped layer 24 is arranged. Within the n-doped layer 24 on the one hand is a p ⁺ -doped region 25 , as well as within a p-doped region 26 an n ⁺ doped area 27 educated. Furthermore, in the n-doped layer 24 an n ⁺ doped area 28 educated. On the semiconductor substrate 31 is also an anode metallization 19 and a cathode metallization 20 deposited. The junctions of the cathode metallization 20 with the n ⁺ doped area 27 and the p-doped region 26 are over insulating areas 29 separated from each other. Further, the anode metallization 19 with the n ⁺ doped area 28 and with the p ⁺ doped region 25 electrically connected while the cathode metallization 20 with the n ⁺ doped area 27 within the p-doped region 26 and the p-doped region 26 is electrically connected. The lateral thyristor results from the sequence of the following doped regions: p ⁺ -doped region 25 , n-doped region 24 , p-doped region 26 and n ⁺ doped area 27 , The bottom of the substrate 31 , in particular the n ⁺ -doped layer 23 is over the connecting line 30 connected to the supply potential + U. The anode metallization 19 is above the n ⁺ doped area 28 , the n-doped layer 24 and the n ⁺ -doped layer 23 connected to the supply potential + U.

5B On the other hand, the structure of a conventional power MOSFET in which in the semiconductor substrate 31 , in particular the n-doped layer 24 , p-doped regions 31 and within these, n ⁺ doped areas 32 are formed. The p-doped regions 31 and the n ⁺ doped regions 32 are via a source connection 33 shorted while gate connections 34 over respective channel zones of the p-doped regions 31 are arranged. The bottom of the substrate 31 is with the drain connection 35 Mistake.

The 6A to 6C show various embodiments of the cell structure of a circuit breaker and a temperature-controlled switching element, which are monolithically integrated in a chip. The hatched rectangles 37 represent the cells of a circuit breaker, while the open rectangles 36 represent the cells of the temperature controlled switching element. 6A shows the case of a monolithic integrated structure of the circuit breaker and the temperature-controlled switching element, in which the cells are arranged in blocks next to each other. 6B shows a case in which the cells 37 of the circuit breaker and the cells 36 the temperature-controlled switching element are interleaved. 6C shows a case in which the cells 37 of the circuit breaker and the cells 36 the temperature-controlled switching element are interleaved in strips. Like that 6B and 6C can be removed, takes the circuit breaker in a nesting of its cells with the cells of the temperature-controlled switching element, a comparatively larger area on the chip surface 38 as in the case of 6A , so that advantageously a comparatively larger heat sink for heat dissipation in case of overheating of the circuit breaker is available. With the in the 6B and 6C shown embodiments of a monolithic integration of the circuit breaker and the temperature-controlled switching element can thus be achieved a delayed or decreased increase in temperature of the circuit breaker when the malfunction occurs "alloying".

1

battery

2

current fuse

3

breakers

4

load

5

Short-circuit switch

6

casing

7

load path

8th

thyristor

9

ECU mass

10

load mass

11

Control input line

12

output line

13

Drain

14

ground connection

15

control logic

16

gate

17

resistance

18

casing

19

anode

20

cathode

21

Lead frame

22

connecting cable

23

n ⁺ -doped layer

24

n-doped layer

25

p ⁺ doped area

26

p-doped Area

27

n ⁺ doped area

28

n ⁺ doped area

29

Quarantine

30

connecting cable

31

p-doped Area

32

n ⁺ doped area

33

source terminal

34

gate terminal

35

Drain

36

cell the temperature-controlled switching element

37

cell of the circuit breaker

38

chip area

39

substratum

Claims (12)

Circuit arrangement with at least one load path ( 7 ), which is a series circuit with a voltage source ( 1 ) for providing a supply potential (+ U), a semiconductor module, a current fuse connected upstream of the semiconductor module ( 2 ), which is suitable for interrupting the current flow in the series circuit when a selectable current threshold value is reached, and at least one load resistance ( 4 ), wherein the semiconductor module comprises a housing ( 18 ) and at least one in the housing ( 18 ) arranged controllable semiconductor switch ( 3 ), characterized by its supply voltage terminals ( 12 . 13 ) is electrically conductively connected to the voltage source and with a loadable control device mass ( 9 ) is electrically conductively connected, wherein in the housing ( 18 ) a temperature-controlled switching element ( 8th ) which is connected to the supply potential (U) and to the control unit ground ( 9 ), wherein the temperature-controlled switching element ( 8th ) is adapted to switch with a temperature increase upon reaching a selectable temperature threshold from a high-impedance, substantially current-blocking off state to a low-impedance, current-permeable on state, whereby an electrically conductive connection from the voltage source ( 1 ) to the control unit mass ( 9 ) whose electrical resistance is a current having a current of at least the current threshold of the current fuse ( 2 ). Circuit arrangement according to claim 1, characterized in that the semiconductor switch and the temperature-controlled switching element as two separate chips on a lead frame ( 21 ) are executed. Circuit arrangement according to Claim 1, characterized that the semiconductor switch and the temperature-controlled switching element are monolithically integrated within a chip. Circuit arrangement according to Claim 3, characterized that the semiconductor switch and the temperature-controlled switching element within a chip with a nested cell structure are monolithically integrated. Circuit arrangement according to one of the preceding Claims, characterized in that the controllable semiconductor switch a Power semiconductor switch, in particular a power MOSFET. Circuit arrangement according to Claim 5, characterized the power semiconductor switch is a smart power semiconductor switch is. Circuit arrangement according to one of the preceding claims, characterized in that the temperature-controlled switching element is a thyristor ( 8th ). Circuit arrangement according to Claim 7, characterized in that the thyristor ( 8th ) in the form of a Lateralthyristors with the controllable semiconductor switch, in particular power MOSFET, is monolithically integrated in a chip. Circuit arrangement according to one of the preceding Claims, characterized in that via the electrically conductive Connection between voltage source and control unit temasse flowing current a size of at least about 2 times until about 3 times the current threshold has. Circuit arrangement according to one of the preceding Claims, characterized in that the temperature-controlled switching element is suitable at a temperature in the range of about 250 ° C to about 350 ° C in to switch its on state. Circuit arrangement according to one of the preceding Claims, characterized in that the voltage source is a supply voltage in the range of about 12 V to about 42 V. Circuit arrangement according to one of the preceding Claims, characterized in that the current threshold of the current fuse in the range of a few amps to about 100 A is.