Miscellaneous active electrical nonlinear devices – circuits – and – Gating – Utilizing three or more electrode solid-state device
Reexamination Certificate
2000-09-11
2001-11-20
Wells, Kenneth B. (Department: 2816)
Miscellaneous active electrical nonlinear devices, circuits, and
Gating
Utilizing three or more electrode solid-state device
C327S424000
Reexamination Certificate
active
06320448
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to a bridge circuit for switching high currents, having n (n=a natural integer) lowside and highside switches in the form of vertically structured MOS transistors on two separate chips. The highside switch is formed using DMOS technology.
Such a bridge circuit is typically used in order to drive motors during direct-current and pulse-width-modulated operation, or to switch valves. The bridge circuit can be produced using different numbers of switches, with a halfbridge being produced if n=1, a full bridge or H-bridge being produced if n=2, a three-phase bridge being produced if n=3. An n-phase bridge is produced in the case of n.
A bridge circuit as mentioned above has become known heretofore from German patent DE 196 95 582 C1. There, all the switches of the bridge circuit, that is to say the lowside switches in addition to the highside switches, are formed using DMOS technology. In order to allow control at a high current level, the chips are arranged one above the other using so-called chip-on-chip mounting. The load paths of two mutually associated transistors are connected in series by virtue of the mounting. One embodiment provides for two highside transistors integrated on a common chip, and two lowside transistors on separate chips. The chip-on-chip mounting of that prior art bridge circuit is a relatively complicated process which, in particular, requires complicated bonding. Furthermore, it is known for bridge circuits to be produced as monolithic circuits for use with low currents, in particular using BCD-MOS technology. The major disadvantage of this implementation is the relatively low operating currents.
Finally, it is also known for the bridge circuit to be produced with discrete power transistors, that is to say with four power transistors for an H bridge circuit and a driver circuit in addition, which is either constructed from discrete components or is designed to be integrated. The discrete construction of the circuit variant admittedly allows large current loads to be switched, but it is time-consuming and occupies a large amount of space.
SUMMARY OF THE INVENTION
The object of the invention is to provide a bridge circuit for switching high currents which overcomes the above-noted deficiencies and disadvantages of the prior art devices and methods of this general kind, and which can be produced cost-effectively and ensures that large currents are switched.
With the above and other objects in view there is provided, in accordance with the invention, a bridge circuit for switching high currents, comprising:
two chips each having a front side and a rear side;
a number n, where n is an integer, of lowside and highside switches separately formed as vertically structured MOS transistors on the two chips;
the highside switch having a source;
the lowside switches being formed with common-source technology and having a source arranged on the rear side of the chip, a drain arranged on the front side of the chip, and a drain connected to the source of an associated the highside switch.
In other word, the lowside switches are implemented in common-source technology with the source arranged on the rear side of the chip, and the drain arranged on the front side of the chip. This results in a bridge circuit in which all the transistors are bonded on an active surface, and high currents an thus be switched with an R}on which is as low as possible.
This circuit furthermore has the advantage that all the possible configurations of the bridge circuit, with 1, 2, 3 or more transistors per chip, can be produced on only two chips. The capability for integrated production has major cost advantages in comparison to the previous bridge circuits mentioned initially.
In accordance with an added feature of the invention, the drains of the transistors of the highside switches are advantageously connected to one another. This connection of the drains of the transistors is carried out in a simple manner by means of leadframes or connecting frames integrated in the chips, and which also provide connections for external components.
In accordance with an additional feature of the invention, a control IC for driving the highside and lowside switches is connected to the switches and integrated in one of the chips containing the highside and lowside switches.
In accordance with another feature of the invention, the control IC is integrated in the chip with bipolar CMOS technology.
In accordance with a further feature of the invention, each of the chips has an integrated control IC for driving the highside and lowside switches, respectively.
In accordance with again an added feature of the invention, a dedicated leadframe or connecting frame is provided on each of the chips for interconnecting the transistors and for connecting external components.
In accordance with a concomitant feature of the invention, the highside switches are formed using DMOS technology or, alternatively, using smart technology.
While, in the prior art devices, the control circuits for the highside and lowside switches have been produced on separate chips or constructed as discrete components, the invention advantageously provides that a control IC for driving the highside and lowside switches jointly is integrated in the chip containing the highside or lowside switches. As an alternative to this, two separate control ICs can be provided, one of which is used specifically for driving the highside switches, while the other is used to control the lowside switches. The respective control IC is implemented in a space-saving manner on the associated chip, that is to say the chip on which the lowside switches are integrated, or the chip on which the highside switches are integrated, and, with suitable technology, allows the production process to be simplified, above all using bipolar CMOS technology.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a bridge circuit for switching high currents, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 4786822 (1988-11-01), Steely
patent: 5081517 (1992-01-01), Contiero et al.
patent: 5119162 (1992-06-01), Todd et al.
patent: 5256582 (1993-10-01), Mosher et al.
patent: 5294823 (1994-03-01), Eklund et al.
patent: 5642247 (1997-06-01), Giordano
patent: 5838515 (1998-11-01), Mortazavi et al.
Dinh Paul
Greenberg Laurence A.
Infineon - Technologies AG
Lerner Herbert L.
Stemer Werner H.
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