Integrated magnetic field sensor-controlled switch devices

Embodiments relate to integrated magnetic field sensor-controlled switch devices, such as transistors, current sources, and power switches, among others. In an embodiment, a magnetic switch and a load switch are integrated in a single integrated circuit device. In embodiments, the device can also include integrated load protection and load diagnostics. Embodiments can provide load switching and optional simultaneous logic signaling, for example to update a microcontroller or electronic control unit (ECU), while reducing space and complexity and thereby cost.

TECHNICAL FIELD

The invention relates generally to switch devices and more particularly to magnetic field sensor-controlled switch devices.

BACKGROUND

Semiconductor Hall sensors are currently used for logic signaling but typically are able to switch only a limited load current. Therefore, two separate devices are currently used: a Hall sensor and a load switching integrated circuit (IC). Usually, in operation, a Hall sensor signal indicative of a switching state is received by a microcontroller which in turn activates the load switching IC. The Hall sensor and the load switching IC are typically soldered on a printed circuit board (PCB). Such a configuration uses more board and package space than is desired and is more complex in terms in of periphery space and wiring, each of which in turn leads to a higher cost.

Therefore, there is a need for improved power switches that take advantage of the robustness and reliability of magnetic field sensors like Hall sensors.

SUMMARY

Embodiments relate to integrated magnetic field sensor-controlled switch devices, such as transistors, current sources, and power switches, among others.

In an embodiment, a magnetic field sensor-controlled device comprises an integrated circuit package; magnetic switch circuitry disposed in the package; and load switch circuitry coupled to the magnetic switch circuitry and disposed in the package.

In an embodiment, a method comprises sensing a magnetic field by a sensor disposed in a package; sending a signal related to the magnetic field by the sensor to a load switch disposed in the package; and selectively switching a load by the load switch according to the signal from the sensor.

In an embodiment, an integrated circuit comprises magnetic field switching circuitry comprising a magnetic field sensor element; load switching circuitry coupled to the magnetic field switching circuitry; and an integrated circuit package housing the magnetic field switching circuitry and the load switching circuitry.

In an embodiment, a magnetic field sensor-controlled device comprises an integrated circuit package; magnetic field switch circuitry arranged in the package; load switch circuitry arranged in the package and coupled to the magnetic field switch circuitry; and a back bias magnetic material coupled to the package.

DETAILED DESCRIPTION

Embodiments relate to integrated magnetic field sensor-controlled switch devices, such as transistors, current sources, and power switches, among others. In an embodiment, a magnetic switch and a load switch are integrated in a single integrated circuit device. In embodiments, the device can also include integrated load protection and load diagnostics. Embodiments can provide load switching and optional simultaneous logic signaling, for example to update a microcontroller or electronic control unit (ECU), while reducing space and complexity and thereby cost.

Referring toFIGS. 1A,1B and2, a block diagram of a magnetic field sensor-controlled switch device100according to an embodiment is depicted. Device100comprises magnetic switch circuitry102and load switch circuitry104integrated in a single package106in an embodiment. In the embodiment ofFIG. 1B, device100also comprises additional circuitry105, which in embodiments can comprise at least one of additional load switch circuitry, integrated load protection circuitry or integrated load diagnostics disposed in package106.

Magnetic switch circuitry102can comprise a Hall-effect sensor, a magnetoresistive (xMR) sensor, a magnetodiode, a magnetotransistor, a magnetic field-sensitive MOSFET (MAGFET) or some other suitable magnetic field or other sensor device in various embodiments. In embodiments, the sensor can further comprise a differential or gradiometric sensor device having multiple sensing elements, which can be more robust against interference magnetic fields. In the embodiment ofFIG. 2, magnetic switch circuitry102comprises at least one Hall-effect sensor element108, such as a Hall plate or a vertical Hall device, configured to detect a position of a magnet. In embodiments, magnetic switch circuitry102is configured to act as a switch and to provide switch logic level information to an external microcontroller110, though this latter feature can be omitted in other embodiments.

Load switch circuitry104, in embodiments, comprises a transistor, such as a field effect transistor (FET), linear current control circuitry, an active power switch such as a high-side power switch, an nMOS device, a pMOS device, a linear current source, a switched current source or some other suitable device configured to switch or other control a load111. For example, load switch circuitry104can comprise a power FET in one embodiment. While device100is depicted comprising a single load switch circuitry104block, other embodiments can comprise a plurality of load switch circuitry104blocks, which can be desired in some applications.

Magnetic switch circuitry102and load switch circuitry104can be configured within package106in various ways. For example, embodiments can comprise single-, dual- or multi-die configurations, including chip-on-chip, chip-by-chip and other suitable arrangements. For example, it can be desired in some embodiments for circuitries102and104to comprise different technologies, such as power technologies with thicker metal layers, particular features (e.g., DMOS or VMOS) and/or non-silicon technologies (e.g., GaN, silicon carbide or GaAs) for load switch circuitry104and CMOS, such as for Hall or xMR sensors. In these and other embodiments, logic, EEPROM and other circuitry can be implemented on a die with magnetic switch circuitry102, where more functions can be implemented on a smaller die size and in less expensive technology, to reduce cost, though this is exemplary of only some embodiments and can vary in others. Separate dies, split, specially shaped and/or non-magnetic leadframes and other configurations and arrangements within package106can also be used in particular embodiments to improve desired thermal characteristics, such as thermal resistance, temperature crosstalk, thermal coupling and thermal isolation, and/or electromagnetic compatibility (EMC), among others.

Referring toFIGS. 3A and 3B, device100can comprise a chip-on-chip configuration of magnetic switch circuitry102and load switch circuitry104on a leadframe113, with an internal pull-up resistor112within package106. The relative chip-on-chip arrangement of circuitries102and104can vary in other embodiments. Switch100can alternatively comprise an external pull-up resistor112. In one embodiment, device100is formed on a single semiconductor die, while in other embodiments a plurality of dies are used.

Referring toFIGS. 4A and 4B, device100can comprise a chip-by-chip configuration of Hall switch circuitry102and load switch circuitry104on leadframe113, with an internal or external pull-up resistor112(depicted as external inFIGS. 4A and 4B).

InFIG. 5, one of magnetic switch circuitry102and load switch circuitry104(not visible) can be mounted on top of the leadframe while the other is mounted on the bottom. In can be advantageous, for example, to mount magnetic switch circuitry102on top of the leadframe such that it can be positioned closer to the magnet to minimize the air gap, with load switch circuitry on the bottom to dissipate more heat to the board.

Different coupling arrangements of magnetic switch circuitry102and load switch circuitry104can also be implemented in other embodiments. In one embodiment, load switch circuitry104can be coupled electrically in series with a current rail of magnetic switch circuitry102. Such a configuration can be used to monitor the current and switch it off if it becomes too large or exhibits some other undesirable feature. In another embodiment, a single terminal of the load switch circuitry104can be coupled with the current rail of magnetic switch circuitry102. Such a configuration can be more versatile by providing end users with the option of connecting the current rail and load switch circuitry104in series, parallel or some other desired configuration. In some embodiments, the current rail of magnetic switch circuitry102can be used as the die paddle for load switch circuitry104, such that the die of load switch circuitry104is mounted onto the current rail. Such a configuration can provide a lower electrical resistance and thermal resistance of load switch circuitry104. These embodiments are examples, and other embodiments can comprise these and/or other configurations.

The configuration of package106and leads114, including the wirebonds as depicted, which can comprise other coupling types and configurations, can also vary in embodiments and/or applications, as appreciated by those skilled in the art. For example, some applications can require a particular external pull-up resistor, while others can select a particular configuration according to price sensitivity or some other characteristic. Device100can comprise virtually surface-mount device (SMD) in embodiments, with a variety of package and lead configurations and types. For example,FIGS. 6A and 6Bdepict three- and four-pin lead embodiments. Embodiments having extended lead lengths can be advantageous in embodiments in applications in which it is desired or required to have flexibility in the positioning of device100. Longer leads provide more options for positioning, such as in remote locations, or the leads can be trimmed for more proximate locations. In another example,FIG. 7depicts an integrated back bias (IBB) embodiment of device100and package106, in which a magnet116is coupled in, on or to package106.

In operation, a single integrated device100can signal load and logic in parallel. A load can be switched by load switching circuitry104by recognizing, by magnetic switch circuitry102, the transgression of a magnetic field strength while, optionally, sending a logic signal to microcontroller110to indicate the change in state. Thus, the load can be driven and switched locally and directly by a single device, as opposed to conventional solutions in which a first device provides a logic signal to the microcontroller, which in turn signals a second device to switch a load.

Referring to the example ofFIGS. 8A and 8B, device100is coupled to a microcontroller110and a load111. A varying magnetic field is represented by a magnet118InFIG. 8A, load111is switched off by device100, whereas inFIG. 8Bthe change in magnetic field when magnet118shifts is sensed by magnetic switch circuitry102(not visible) such that, in parallel, the state of load111is switched, and microcontroller110is informed. In other embodiments, the switching can operate in the opposite manner or some other way, withFIGS. 8A and 8Bbeing used to illustrate but one simplified example.

Switch100has many applications, including lighting, domestic appliance, lifestyle and automotive, among others. Specific, though non-limiting, examples include cosmetics mirrors, drawer and cupboard lighting, automotive and vehicular brake lights, and refrigerator/freezers. Switch100comprising a low-power magnetic switch can also be used for autonomous power saving lighting applications. Additionally, embodiments can be used as LED drivers, linear current sources or switching current regulators, such as for integrated magnetic LED switches. In some embodiments, loads can be about 100 mA to about 50 A or more, for example about 100 mA to about 5 A, or about 1 A to about 20 A, or some other range, with voltages of about 1 V to about 35 V or more, though these ranges can vary in other embodiments.

Embodiments provide many advantages. Cost savings can be realized with respect to conventional solutions because only a single package is necessary. The single package also requires less space, less wiring and fewer peripheries. For example, low-cost construction can include a solid-state relay mounting. With respect to functionality, the load is switched directly by the switch, rather than by a microcontroller, which becomes optional. In embodiments having a microcontroller, the microcontroller is always updated, and lifetime advantages can be realized in view of the robustness, reliability and durability of Hall switches as opposed to conventional mechanical solutions. Embodiments also provide improved controllability of switching activities.

Persons of ordinary skill in the relevant arts will recognize that the invention may comprise fewer features than illustrated in any individual embodiment described above. The embodiments described herein are not meant to be an exhaustive presentation of the ways in which the various features of the invention may be combined. Accordingly, the embodiments are not mutually exclusive combinations of features; rather, the invention may comprise a combination of different individual features selected from different individual embodiments, as understood by persons of ordinary skill in the art.