Current sensor integrated circuits

A current sensor integrated circuit (IC) includes a unitary lead frame having at least one first lead having a terminal end, at least one second lead having a terminal end, and a paddle having a first surface and a second opposing surface. A semiconductor die is supported by the first surface of the paddle, wherein the at least one first lead is electrically coupled to the semiconductor die and the at least one second lead is electrically isolated from the semiconductor die. The current sensor IC further includes a first mold material configured to enclose the semiconductor die and the paddle and a second mold material configured to enclose at least a portion of the first mold material, wherein the terminal end of the at least one first lead and the terminal end of the at least one second lead are external to the second mold material.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

FIELD

This invention relates generally to current sensor integrated circuits and more particularly to packaging structures and techniques for current sensor integrated circuits.

BACKGROUND

Some electrical current sensors use one or more magnetic field sensing elements in proximity to a current-carrying conductor. The magnetic field sensing elements generate an output signal having a magnitude proportional to the magnetic field induced by the current through the conductor.

In applications in which the conductor can be at a relatively high voltage, safety specifications require that a certain electrical isolation be maintained between the conductor and other parts of the circuitry (e.g., signal leads coupled to an external system on which the sensor output signal is communicated). The term “creepage” refers to the shortest distance between two conductive parts along the surface of any insulation material common to two conductive parts. The creepage requirement is based on the distance necessary to withstand a given working voltage (i.e., the highest voltage level that insulation under consideration can be subjected to when the current sensor is operating in normal use).

Various parameters characterize the performance of such current sensors, including sensitivity. Sensitivity is related to the magnitude of a change in output voltage from the magnetic field transducer in response to a sensed current. The sensitivity of a current sensor is related to a variety of factors. One important factor is the physical separation between the magnetic field transducer/sensor and the current conductor, sometimes referred to as the “active area depth”.

Current sensing accuracy can also be affected by mechanical dimensional/positional tolerance considerations. Accuracy is improved by providing tightly controllable, repeatable manufacturing structures and techniques for the sensor. Some current sensors require different components or subassemblies to be manually positioned and/or aligned during the manufacturing process, which can introduce misalignments that adversely affect sensing accuracy.

SUMMARY

Described herein are structures and manufacturing methods directed towards providing current sensor integrated circuits (ICs) that meet creepage requirements for high voltage applications with a reduced active area depth by down setting a paddle of the IC lead frame. The described current sensor IC is provided with tighter manufacturing tolerances as a result of improved coplanarity of the lead frame and avoiding manual alignment requirements during manufacture by utilizing a unitary lead frame. By providing current sensor ICs with these attributes, current sensing accuracy is improved.

According to the disclosure, a current sensor integrated circuit includes a unitary lead frame including at least one first lead having a terminal end, at least one second lead having a terminal end, and a paddle having a first surface and a second opposing surface. A semiconductor die is supported by the first surface of the paddle, wherein the at least one first lead is electrically coupled to the semiconductor die and the at least one second lead is electrically isolated from the semiconductor die. A first mold material is configured to enclose the semiconductor die and the paddle and a second mold material configured to enclose at least a portion of the first mold material, wherein the terminal end of the at least one first lead and the terminal end of the at least one second lead are external to the second mold material.

Features may include one or more of the following individually or in combination with other features. In some embodiments, the second mold material may be configured to fully enclose the first mold material. In other embodiments, the second mold material is configured to enclose a portion of the first mold material and to expose a surface of the first mold material. The paddle can be supported by the at least one first lead. The lead frame can include at least one dummy lead that is electrically isolated from the semiconductor die, wherein the paddle is supported by the at least one dummy lead.

The paddle can be down set with respect to the terminal end of each of the at least one first lead and the terminal end of the at least one second lead. A distance of the down set of the paddle is based on an active area depth and creepage distance requirements of the sensor IC.

The at least one first lead has a first portion extending from an edge of the second mold material outside of the second mold material in a first direction and a second portion enclosed by the second mold material and extending from the edge of the second mold material inside the second mold material in a second direction to the down set paddle, wherein the second direction can be substantially opposite to the first direction. The second mold material has a first surface, a second surface parallel to the first surface, and a side surface extending from the first surface to the second surface, wherein the first and second portions of the at least one first lead meet at a junction between a first portion of the second mold material and a second portion of the second mold material positioned at the side surface of the second mold material.

In use, the first surface of the second mold material can be adjacent to a current conductor external to the current sensor IC. A distance from the first surface of the second mold material to the second surface of the second mold material establishes a thickness of the sensor IC and the thickness can be selected based on a creepage requirement of the sensor IC. The at least one first lead can extend external to the second mold material on a first side of the second mold material and the at least one second lead can extend external to the second mold material on at least one second side of the second mold material orthogonal with respect to the first side. The terminal end of the at least one first lead and the terminal end of the at least one second lead can be configured for surface mount attachment. The at least one first lead can be electrically coupled to the semiconductor die by a wire bond.

Also described is a method of manufacturing a current sensor IC including providing a lead frame including at least one first lead having a terminal end, at least one second lead having a terminal end, and a paddle and attaching a semiconductor die to the paddle. The at least one first lead is electrically coupled to the semiconductor die and the at least one second lead is electrically isolated from the semiconductor die. The method further includes molding a first mold material to enclose the semiconductor die and the paddle, forming the at least one first lead to down set the paddle with respect to the terminal end of the at least one first lead, molding a second mold material to enclose at least a portion of the first mold material and to expose the terminal end of the at least one first lead and the terminal end of the at least one second lead, and forming the terminal end of at least one first lead and the terminal end of the at least one second lead for surface mount attachment.

Features may include one or more of the following individually or in combination with other features. The lead frame can be provided from a unitary, coplanar lead frame strip. The lead frame can further include at least two dam bars configured to attach the lead frame to one or more lead frames of other current sensor ICs, wherein the method further includes removing at least one dam bar after molding the first mold material and before forming the at least one first lead to down set the paddle with respect to the terminal end of the at least one first lead. The method can further include removing at least one dam bar after molding the second mold material. In some embodiments, molding the second mold material to enclose at least a portion of the first mold material can include enclosing all surfaces of the first mold material. In other embodiments, molding the second mold material to enclose at least a portion of the first mold material can include exposing a surface of the first mold material. Molding the first mold material can include placing the lead frame and the semiconductor die into a first chase comprising a first cavity and a second cavity and introducing the first mold material through an opening in the first chase, wherein the at least one first lead extends external to the first mold material at a junction between the first cavity and the second cavity. Molding the second mold material can include placing the lead frame and the first mold material into a second chase including a first cavity and a second cavity and introducing the second mold material through an opening in the second chase, wherein the at least one first lead and the at least one second lead extend external to the second mold material at a junction between the first cavity and the second cavity.

DETAILED DESCRIPTION

Referring toFIGS. 1, 1A, and 1B, a current sensor IC10includes a unitary lead frame20having at least one first lead30(and here six leads30a-30f), at least one second lead40(and here four leads40a-40d), and a paddle50having a first surface50aand a second, opposing surface50b. Each of the first leads30a-30fhas a respective terminal end34a-34fand each of the second leads40a-40dhas a respective terminal end44a-44d. A semiconductor die54is supported by the first surface50aof the paddle50. The first leads30a-30fare electrically coupled to the semiconductor die54and the second leads40a-40dare electrically isolated from the semiconductor die.

A first mold material60is configured to enclose the semiconductor die54and the paddle50and a second mold material70is configured to enclose at least a portion of the first mold material60. The second mold material70can be considered to form a package or package body from which lead portions can extend to permit electrical or other connection to external circuits and systems as will become apparent. The terminal ends34a-34fof the first leads30a-30fand the terminal ends44a-44dof the second leads40a-40dare external to the second mold material70.

The second mold material70has a first surface70a, a second surface70bparallel to the first surface, and side surfaces70c-70fextending from the first surface to the second surface, as shown. In the example sensor10, first leads30a-30fextend external to the second mold material70on a first side70cof the second mold material and second leads40a-40dextend external to the second mold material70on a side (i.e., mold material side70eand/or side70f) of the second mold material orthogonal with respect to the first side.

The semiconductor die54is configured to support one or more magnetic field sensing elements (seeFIG. 10) to detect a magnetic field generated by a current in a proximate, external conductor as shown and described below in connection withFIGS. 9 and 9A. Suffice it to say here that in use, the current sensor10is positioned with respect to an external conductor such that the surface70aof the second mold material is proximate to the conductor.

A distance labeled74from the first surface70aof the second mold material70to exposed portions of the leads30a-30f,40a-40dcorresponds to the creepage of the sensor IC10as it represents the minimum distance between an external conductor and the leads through the second mold material. In an example sensor, the creepage requirement can be on the order of 5 mm for a 450V application or 9 mm for a 900V application.

In order to achieve a relatively small active area depth, it is desirable for an active surface54aof the die54(i.e., the surface that supports magnetic field sensing elements) to be close to the conductor and thus, close to the surface70aof the second mold material70that is proximate to the conductor in use. The distance from the active die surface54ato the conductor can be as small as the distance labelled76inFIG. 1Bin applications in which the package surface70ais flush against the conductor.

Satisfying the competing requirements of providing a small active area depth76while also establishing a required minimum creepage distance labeled74inFIG. 1Bcan be challenging. In order to address these competing requirements, paddle50is “down set” with respect to the terminal ends34a-34fof the first leads30a-30fand the terminal ends44a-44dof the second leads40a-40d, as shown. As will become apparent in connection withFIGS. 4 and 4Abelow, the paddle50is down set after a primary package200(FIG. 2) of the sensor IC10is molded and a dam bar is removed. The down set distance labeled78refers to the distance between the paddle50and a portion of the leads30a-30fextending external to the second mold material. It will be appreciated that the down set distance78can be selected to achieve a desired active area depth76and required creepage distance74for the current sensor10.

As will be discussed below, the second mold material70has a first portion80and a second portion82, which portions meet at a junction, or parting line84shown along the side surfaces70c-70f. As can be seen inFIG. 1Aand labeled with respect to example lead30a, each of the leads30a-30fand40a-40dhas first, external portion90extending from an side surface70cof the second mold material70outside of the second mold material (i.e., external to the package) in a first direction (i.e., generally upward in the view ofFIG. 1A) and a second, internal portion92enclosed by the second mold material and extending from the side surface70cof the second mold material70inside the second mold material in a second direction (i.e., generally downward the view ofFIG. 1A) to the down set paddle50, with the second direction being substantially opposite to the first direction. The first and second directions in which the leads30a-30fextend can be substantially vertical with respect to the IC10as illustrated. With this arrangement of first, external lead portions (e.g.,90) extending in a different, substantially vertical direction than second, internal lead portions (e.g.,92), which second, internal lead portions extend to the down set paddle50, a current conductor (FIG. 9) can be attached or otherwise positioned proximate to the first surface70aof mold material70without interference or restriction by lead connections.

Second mold material70can be considered to form the IC package10from which the external portion of the leads extend in order to permit electrical connection to other circuits and systems (not shown). Various arrangements are possible for connecting the leads30a-30fto external components and systems. The example sensor10is configured for surface mount attachment to a printed circuit board or other suitable substrate and so, the terminal ends34a-34fof leads30a-30fare formed and plated for surface mount attachment. It will be appreciated by those of skill in the art that the terminal ends34a-34fof leads30a-30fcan alternatively be provided for other types of circuit board attachment such as through hole attachment for example. Leads44a-44dare also formed and plated for surface mount attachment and, while leads44a-44dare not electrically connected to sensor circuitry, they are instead provided to enhance mechanical mounting stability by balancing the package when the IC is attached to a circuit board by surface mount technology (see e.g.,FIG. 9).

In current sensor10ofFIGS. 1, 1A, 1B, the second mold material70is configured to fully enclose the first mold material60as shown inFIG. 1B. In other embodiments, as shown and described in connection withFIG. 7below, the second mold material70is configured to enclose only a portion of the first mold material60and to expose a surface of the first mold material.

Referring also toFIG. 2, a primary package200that forms part of the current sensor IC10includes a first portion of lead frame20(including first leads30a-30fand paddle50), semiconductor die54, and first mold material60. The first mold material60encloses the semiconductor die54and the paddle50, as shown. The primary package200has a form similar to a single in-line package (SIP).

Semiconductor die54supports magnetic field sensing elements (e.g., sensing elements56a,56b) and other elements and circuitry to permit current detection as will be explained in connection with the example current sensor ofFIG. 10. In order to permit electrical connection between the current sensor IC10and external circuits and systems, one or more of the first leads30a-30fare coupled to the semiconductor die54. Various structures and techniques are suitable for permitting such electrical connection, such as the illustrated wire bonds58that can be coupled between bond pads on the semiconductor die54and the signal leads30a-30f. The wire bonds58and a portion of the electrically connected leads are enclosed by the first mold material60, as shown.

Paddle50is supported by at least one first lead30a-30fand, in the example embodiment is supported by leads30a,30f, as may provide an electrical ground connection for the IC10. Additionally, as shown in connection withFIG. 3, the lead frame20may include one or more “dummy” leads, or tie bars (i.e., leads that are not electrically connected within the package10and thus are electrically isolated from the semiconductor die54) which may additionally support the paddle50.

Fabrication of the primary package200is discussed below in connection withFIGS. 4 and 8. Suffice it to say here that the first mold material60includes a first portion66and a second portion68, which portions meet at a junction, or parting line64. Tapers62of the first and second mold portions66,68can facilitate removal from mold chases.

Fabrication of IC10is described in connection withFIGS. 3-8. Referring toFIG. 3, lead frame20is shown at a stage of manufacture to include first leads30a-30f, second leads40a-40d, paddle50, tie bars32, and dam bars36a,36b. Tie bars32and dam bars36a,36bfacilitate manufacture by maintaining lead frame coplanarity and desired lead spacing and also providing a stopping point for liquid molding compound during processing and also enhance the strength of the resulting lead frame structure.

Advantageously, lead frame20is a unitary structure. By “unitary” it is meant that the lead frame20is formed from a single structure, such as a lead frame strip. With this arrangement, tighter manufacturing tolerances can be achieved than otherwise possible with conventional configurations that require multiple, sometimes manual, alignment steps, thereby permitting more repeatable and accurate current sensing results. By having the first mold material60and second mold material70share the same lead frame20, better control of the coplanarity of the leads as well as the active area depth can be achieved.

During manufacture, lead frame20is formed from a coplanar sheet or strip of metal that is patterned (e.g., stamped, etched) to provide the desired lead frame features (e.g., leads30a-30f, leads40a-40d, paddle50, tie bars32, and dam bars36a,36b). Generally, a plurality of lead frames like lead frame20are formed from the same metal sheet and dam bars36a,36band tie bars32hold together the lead frame20with other lead frames (not shown). Once the current sensor10is fabricated (e.g., according toFIGS. 3-8), the current sensor10is separated (i.e., singulated) from other sensors (not shown) formed from the same lead frame material as discussed below. The thickness of the lead frame20can vary.

Referring also toFIG. 4, lead frame20is shown at a later stage of manufacture of the current sensor10. InFIG. 4, (although not visible in this view since it is attached to the “bottom” surface of the paddle50) the semiconductor die54is attached to the paddle50. Various materials and techniques are possible for attaching the die54to the paddle50, including use of an adhesive tape or epoxy for example.

Also in the structure ofFIG. 4(although not visible in this view since it is on the bottom surface of the paddle), the die54is attached to one or more leads30a-30f(such as with wire bonds58,FIG. 2). The first mold material60is molded to enclose the die54and paddle50. Also, in the structure ofFIG. 4, one of the dam bars36ais removed to permit first leads30a-30fto be formed (i.e., bent). Thus, the primary package structure (FIG. 2) has been fabricated inFIG. 4. And although not shown in this view, first mold material60can have tapers62(FIG. 2) to facilitate removal from the mold chase.

Referring also to the simplified side view ofFIG. 4A, the lead frame20is formed (i.e., bent) to provide the above-described down set of the die paddle50, as shown. As noted above, the down set distance (e.g., distance78inFIG. 1B) is based on the creepage and active area depth requirements of the sensor10.

Referring also toFIG. 5, at a later stage of manufacture of the current sensor10, the second mold material70is molded to enclose at least a portion of the first mold material60and here, to fully enclose the first mold material as can be seen from the simplified side view ofFIG. 5A. As can be seen inFIG. 5A, the second mold material70includes first portion80and second portion82meeting at junction, or parting line84. The molding process by which the second mold material70is formed is described further below in connection withFIG. 8. Suffice it to say here that, preferably the first and second portions80,82have tapers86to facilitate removal from the mold chase.

Referring also toFIG. 6, at a still later stage of manufacture of the current sensor10, dam bar36bis removed. Also shown inFIG. 6and in the simplified side view ofFIG. 6A, the terminal ends34a-34fof the first leads30a-30fand the terminal ends44a-44dof the second leads40a-40dare bent and plated to permit surface mount attachment to a printed circuit board or other substrate in use. As noted above, while leads44a-44dare not electrically connected to sensor circuitry, they are instead provided to enhance mechanical mounting stability when the IC is attached to a circuit board in use (FIG. 9).

Referring also toFIG. 7, an alternative current sensor is substantially similar to the sensor ofFIG. 5Aand thus, like reference numbers are used for like elements. The sensor ofFIG. 7differs from the sensor ofFIG. 5Aonly in that the second mold material70′ does not fully enclose the first mold material60. Rather, a surface60aof the first mold material60is exposed and so is flush with the surface70a′ of the second mold material70′. This configuration can be advantageous in order to further reduce the active area depth by permitting the active surface54aof the die54to be even closer to the conductor in use.

Referring also toFIG. 8, a flow diagram illustrates an example manufacturing process800for the current sensor IC10, beginning at block802with providing lead frame20including at least one first lead, such as leads30a-30f, at least one second lead, such as leads40a-40d, and a paddle, such as paddle50, as shown inFIG. 3.

At block804, a semiconductor die, such as die54, is attached to the paddle50and in block808, at least one first lead is electrically coupled to the die. For example, one or more leads30a-30fcan be coupled to bond pads of the die by wire bonds58(FIG. 2).

At block812, first mold material60is molded to enclose the die54and paddle50so as to provide the primary package200ofFIG. 2. Various molding techniques are possible, including but not limited to injection molding, compression molding, transfer molding, and/or potting, with various materials suitable to electrically isolate and mechanically protect the device. Suitable materials for the mold material60include thermoset and thermoplastic mold compounds and other commercially available IC mold compounds.

Referring also toFIG. 2, in the example embodiment, the first mold material60can be formed by a transfer molding process, in which the subassembly including the lead frame20and die54(with the die attached to the lead frame by wire bonds58) is positioned in a chase including mated cavities. Mold material60is injected into the mated cavities through a gate, or opening to fill the cavities. After sufficient time has passed, the mold material60is partially cured and then the mold cavities are separated, and the molded body60is “ejected” from the cavities as can be facilitated by tapers62of the first and second portions66,68of mold material60,FIG. 2. The molded body60is then fully cured at high temperature to improved mechanical strength of the molded body.

Once the primary package200is fabricated, multiple portions of dam bar36aare removed, then first leads30a-30fare formed (i.e., bent or pushed down from the original plane of the lead frame20) at block816so as to generate the structure shown inFIGS. 4 and 4A. More particularly, the tie bars32are trimmed along a line38(FIG. 3), following which the molded primary package is pushed down to achieve the down set as can be seen inFIG. 4A.

At block820, the second mold material70is molded to enclose at least a portion of the first mold material60and to expose the terminal ends34a-34fof leads30a-30fand the terminal ends44a-44dof leads40a-40d. For example, the second mold material70can be formed by transfer molding, in which the subassembly shown inFIGS. 4 and 4Ais positioned in a chase including mated cavities. Mold material70is injected into the mated cavities through a gate, or opening to fill the cavities. After sufficient time has passed, the mold material70is partially cured and then the mold cavities are separated, and the molded body70is “ejected” from the cavities. The molded body70is then fully cured at high temperature to improved mechanical strength of the molded body. Removal of the mold material70from the chase can be facilitated by tapers86of the first and second portions80,82of mold material70(FIG. 5A). The resulting structure is shown inFIGS. 5 and 5Afor example, in which the first and second portions80,82meet at junction84.

Thereafter at block824, multiple portions of dam bar36bare removed, then terminal end34a-34fof the first leads30a-30fand terminal ends44a-44dof second leads40a-40dare processed according to the desired mounting technique. The illustrated terminal ends34a-34f,44a-44dthat have been plated are bent to permit surface mount attachment to a printed circuit board (FIG. 9A) or other suitable substrate, as shown inFIGS. 6 and 6Afor example.

Referring also toFIGS. 9 and 9A, example current sensor system900includes the current sensor IC10(FIGS. 1, 1A, 1B) secured to an external current conductor904and printed circuit board910or other suitable substrate in use.FIG. 9Ais a plan view of the current sensor system900viewed from the top of the assembly inFIG. 9.

Conductor904may be formed from a conductive material, such as copper. In some embodiments, conductor904may be provided in the form of a bus bar or a flat conductor. Features of the current conductor904can include notches906to form a narrowed, neck region908of the conductor with which the current sensor10is aligned in use, as shown inFIG. 9A. More particularly, in some applications, it may be desirable to align sensor10with the conductor904such that the sensing elements56a,56bare positioned on either side of the narrowed neck region908, as shown. Narrowed region908can improve the coupling factor to the conductor.

Various structures and configurations are suitable for securing the current sensor10to conductor904. For example, one or more clips, adhesive or adhesive tape, or mechanical securing structures may be used. By way of a non-limiting example, clips can retain the printed circuit board910in secure attachment to the conductor904and may include a thermally conductive material to transfer heat away from the printed circuit board. As another example, one or more pegs or other protrusions can be molded on the surface70aof mold material70for mating with complementary holes in the conductor904.

Printed circuit board910permits electrical or other connection to circuits and systems external to the current sensor10. For example, leads34a-34f(FIG. 1) can be electrically connected to signal traces on printed circuit board910such as with surface mount connection. Leads40a-40dcan be mechanically secured to printed circuit board910, but without further electrical connection within the current sensor10since, as explained above, leads40a-40dcan be provided for purposes of mechanical stability.

Distance914corresponds to the active area depth of the system (i.e., the distance between the sensing elements56a,56band the current conductor904). Distance916corresponds to the creepage distance (i.e., the distance between external conductor904and the exposed portion of leads through the second mold material70).

Referring toFIG. 10, a schematic block diagram of an example current sensor1000as can be manufactured as described above, includes one or more magnetic field sensing elements, and here two sensing elements1010a,1010b. Sensing elements1010a,1010bcan be Hall effect elements or other magnetic field transducer element types. It will be appreciated that sensor1000is presented as a non-limiting example of circuitry suitable for sensor10.

Use of two or more sensing elements1010a,1010bpermits differential magnetic field sensing, as may be advantageous to improve immunity (i.e., insensitivity) to common-mode stray magnetic fields. The output of the sensor VOUT is proportional to ΔB=BR−BLwhere BRrepresents magnetic field incident on one of the sensing elements (e.g., so-called “right” sensing element1010b) and BLrepresents magnetic field incident on the other one of the sensing elements (e.g., so-called “left” sensing element1010a). The sensor output VOUT is also affected by the sensitivity, a, of the signal path to magnetic field and can be represented as follows:
VOUT=α×ΔB(1)

The relationship between the conductor current to be measured and the differential field ΔB can be represented by a coupling factor, CF as follows:
ΔB=CF×I(2)
It will be appreciated that coupling factor CF corresponds to coupling between a given current sensor and a proximate conductor.

While differential sensing may be implemented, for example using two sensing elements as shown, in some embodiments, the current sensor can include only a single sensing element. Furthermore, it will also be appreciated that differential sensing can be implemented with more than two sensing elements and can include the use of sensing elements arranged in a bridge configuration.

Example current sensor1000has three pins in this embodiment, including a VCC (supply voltage) pin1001, a VOUT (output signal) pin1002, and a GND (ground) pin1003. The VCC pin1001is used for the input power supply or supply voltage for the current sensor1000. A bypass capacitor, CBYPASS, can be coupled between the VCC pin1001and ground. The VCC pin1001can also be used for programming the current sensor1000. The VOUT pin1002is used for providing the output signal for the current sensor1000to circuits and systems (not shown) and can also be used for programming. An output load capacitance CL is coupled between the VOUT pin1002and ground. The example current sensor1000can include a first diode D1coupled between the VCC pin1001and chassis ground and a second diode D2coupled between the VOUT pin1002and chassis ground.

Magnetic field signals generated by the magnetic field sensing elements1010a,1010bare coupled to a dynamic offset cancellation circuit1012, which is further coupled to an amplifier1014. The amplifier1014is configured to generate an amplified signal for coupling to the signal recovery circuit1016. Dynamic offset cancellation circuit1012may take various forms including chopping circuitry and may function in conjunction with offset control1034to remove offset that can be associated with the magnetic field sensing elements1010a,1010band/or the amplifier1014. For example, offset cancellation circuit1012can include switches configurable to drive the magnetic field sensing elements (e.g., Hall plates) in two or more different directions such that selected drive and signal contact pairs are interchanged during each phase of the chopping clock signal and offset voltages of the different driving arrangements tend to cancel. A regulator (not shown) can be coupled between supply voltage VCC and ground and to the various components and sub-circuits of the sensor1000to regulate the supply voltage.

A programming control circuit1022is coupled between the VCC pin1001and EEPROM and control logic1030to provide appropriate control to the EEPROM and control logic circuit. EEPROM and control logic circuit1030determines any application-specific coding and can be erased and reprogrammed using a pulsed voltage. A sensitivity control circuit1024can be coupled to the amplifier1014to generate and provide a sensitivity control signal to the amplifier1014to adjust a sensitivity and/or operating voltage of the amplifier. An active temperature compensation circuit1032can be coupled to sensitivity control circuit1024, EEPROM and control logic circuit1030, and offset control circuit1034. The offset control circuit1034can generate and provide an offset signal to a push/pull driver circuit1018(which may be an amplifier) to adjust the sensitivity and/or operating voltage of the driver circuit. The active temperature compensation circuit1032can acquire temperature data from EEPROM and control logic circuit1030via a temperature sensor1015and perform necessary calculations to compensate for changes in temperature, if needed. Output clamps circuit1036can be coupled between the EEPROM and control logic1030and the driver1018to limit the output voltage and for diagnostic purposes. For example, if the total output range can be from 0V to 5V, for magnetic fields from 0 G to 1000 G, it may be desired to use a clamp at 0.5V for any field below 100 G. For example, it may be known that below 100 G, the sensor1000does not generate a trustable signal. Hence, if the IC output is 0.5V, it is evident that the measurement is not valid and cannot be trusted. Or clamps at 1V and 4V could be used and the 0-1V and 4-5V ranges can be used for communicating diagnostic information (e.g., 4.5V on the output could indicate “Hall plate is dead” and 0.5V could indicate “Undervoltage VCC detected”, etc.). An undervoltage detection circuit1026can operate to detect an undervoltage condition of the supply voltage level VCC. It will be appreciated that whileFIG. 10shows an example current sensor1000primarily as a digital implementation, any appropriate current sensor can be used in accordance with the present disclosure, including both digital, analog, and combined digital and analog implementations.

Having described preferred embodiments, it will now become apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may be used. Elements of different embodiments described herein may be combined to form other embodiments not specifically set forth above. Various elements, which are described in the context of a single embodiment, may also be provided separately or in any suitable subcombination. Other embodiments not specifically described herein are also within the scope of the following claims.

It is felt therefore that these embodiments should not be limited to disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims.