Packaged Current Sensor Integrated Circuit

Abstract

The packaged current sensor integrated circuit (300) includes a primary conductor (330) having an input portion (332) and an output portion (334) configured to carry a current that is measured by a magnetic field sensing element (309a, 309b) supported by a semiconductor die (308) adjacent the primary conductor. The primary current path includes mechanical locking mechanisms (355a, 355b). The thickness of the molded body of the package is reduced to improve vibration resistance.

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part application and claims priority to and the benefit of U.S. patent application Ser. No. 17 / 409,011, entitled "Packaged Current Sensor Integrated Circuit," filed on August 23, 2021, which is incorporated herein by reference. [Background technology]

[0002]

[0002] Some conventional current sensors are placed in proximity to a current-carrying conductor to sense the magnetic field generated by the current passing through the conductor. The current sensor produces an output signal having a magnitude proportional to the magnetic field induced by the current passing through the conductor. Summary of the Invention

[0003]

[0003] In accordance with the present disclosure, a packaged current sensor integrated circuit includes a primary conductor having input and output leads, a first die mount portion, a second die mount portion, and a current conductor portion between the first die mount portion and the second die mount portion, the primary conductor configured to conduct current from the input lead through the first die mount portion, the current conductor portion, the second die mount portion, and to the output lead, and at least one of the first and second die mount portions has a die mount portion edge adjacent to a respective one of the input or output leads. The packaged current sensor integrated circuit further includes a mechanical locking mechanism spaced apart from the die attach portion edge, at least one secondary lead, a semiconductor die supported by the first and second die attach portions, at least one magnetic field sensing element supported by the semiconductor die and positioned adjacent to the current conductor portion, and a package body enclosing the semiconductor die and at least a portion of the primary conductor, the input lead and the output lead extending from a first side of the package body and the at least one secondary lead extending from a second side of the package body opposite the first side of the package body.

[0004]

[0004] Features may include one or more of the following features individually or in combination with other features. The packaged current sensor integrated circuit may further include at least three secondary leads. The at least one secondary lead may provide an output connection, a voltage input connection, and a ground connection. The packaged current sensor integrated circuit may further include a front-end amplifier, and the at least one magnetic field sensing element is connected to the front-end amplifier. The at least one magnetic field sensing element may be a Hall effect sensor. The packaged current sensor integrated circuit may further include a Hall effect current driver circuit connected to the Hall effect sensor. The Hall effect sensor may be disposed adjacent to a current conductor portion of the primary conductor. The at least one magnetic field sensing element may include a first Hall effect sensor disposed adjacent to a first side of the current conductor portion, and the packaged current sensor integrated circuit may further include a second Hall effect sensor disposed adjacent to a second side of the current conductor portion opposite the first side. The front-end amplifier may be connected to an amplifier for providing an output of the current level in the primary conductor. The packaged current sensor integrated circuit may further include a wafer backside coating material on the backside of the semiconductor die. The packaged current sensor integrated circuit may further include a second wafer backside coating material on the backside of the semiconductor die. The distance between the primary conductor lead frame and the at least one secondary lead frame may be at least 0.125 mm. The mechanical locking mechanism may be spaced from the die attachment edge portion by at least 0.50 mm. The current conductor portion of the primary conductor may define a conductor area. The thickness of the package body may be less than 1.0 mm. The thickness of the primary conductor lead frame may be between 0.140 mm and 0.162 mm.

[0005] A method of sensing current in a current sensor integrated circuit package is also described, the method including providing a primary conductor having input and output leads, a first die attach portion, a second die attach portion, and a primary conductor portion, the primary conductor configured to pass current from the input leads through the first die attach portion, the primary conductor portion, the second die attach portion, and the output leads. The method further includes providing a mechanical locking mechanism within the primary conductor spaced apart from a die attach portion edge, providing at least one secondary lead, providing a semiconductor die disposed adjacent to the primary conductor, providing at least one magnetic field sensing element supported by the semiconductor die, the at least one magnetic field sensing element being disposed proximate the primary conductor portion, and providing an output signal representative of the current in the primary conductor.

[0006]

[0006] Features may include one or more of the following features individually or in combination with other features: The method may include providing at least one magnetic field sensing element as a first magnetic field sensing element disposed adjacent a first side of the current conductor portion, and the method may further include providing a second magnetic field sensing element disposed adjacent a second side of the current conductor portion opposite the first side. The method may further include providing the magnetic field sensing element as one of a planar Hall effect element, a vertical Hall effect element, an anisotropic magnetoresistance (AMR) element, a giant magnetoresistance (GMR) element, or a tunneling magnetoresistance (TMR) element.

[0007]

[0007] The foregoing features of the disclosure, as well as the disclosure itself, can be more fully understood from the following description of the drawings. [Brief description of the drawings]

[0008] [Figure 1]FIG. 1 provides a top view of a packaged current sensor integrated circuit. [Figure 1A]

[0009] FIG. 2 illustrates a cross-sectional side view of the packaged current sensor integrated circuit package of FIG. 1. [Figure 1B]

[0010] 2 is a diagram illustrating the bottom view of the packaged current sensor integrated circuit of FIG. 1. [Figure 1C]

[0011] FIG. 2 is a side view of the packaged current sensor integrated circuit of FIG. 1. [Diagram 2]

[0012] FIG. 2 provides an example circuit for the packaged current sensor integrated circuit die of FIG. 1. [Diagram 3]

[0013] FIG. 1 provides a top view of a packaged integrated circuit having a small form factor. [Figure 3A]

[0014] FIG. 4 is a side cross-sectional view taken along line AA' in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009]

[0015] As used herein, the term "magnetic field sensing element" is used to describe various electronic elements that can sense a magnetic field. The magnetic field sensing element can be, but is not limited to, a Hall effect element, a magnetoresistance element, or a magnetotransistor. As is known, there are different types of Hall effect elements, for example, planar Hall elements, vertical Hall elements, and circular vertical Hall (CVH) elements. As is also known, there are different types of magnetoresistance elements, for example, semiconductor magnetoresistance elements such as indium antimonide (InSb), giant magnetoresistance (GMR) elements, for example, spin valves, anisotropic magnetoresistance elements (AMR), tunneling magnetoresistance (TMR) elements, and magnetic tunnel junctions (MTJs). The magnetic field sensing element may be a single element, or alternatively, may include two or more magnetic field sensing elements arranged in various configurations, for example, a half bridge or a full (Wheatstone) bridge. Depending on the device type and other application requirements, the magnetic field sensing element may be a device made of type IV semiconductor materials such as silicon (Si) or germanium (Ge), or of type III-V semiconductor materials such as gallium arsenide (GaAs) or indium compounds, e.g., indium antimonide (InSb).

[0010]

[0016] As is known, some of the above magnetic field sensing elements tend to have an axis of greatest sensitivity parallel to the substrate supporting the magnetic field sensing element, and others of the above magnetic field sensing elements tend to have an axis of greatest sensitivity perpendicular to the substrate supporting the magnetic field sensing element. In particular, planar Hall elements tend to have an axis of greatest sensitivity perpendicular to the substrate, and metal-based or metallic magnetoresistance elements (e.g., GMR, TMR, AMR) and vertical Hall elements tend to have an axis of greatest sensitivity parallel to the substrate.

[0011]

[0017] As used herein, the term "magnetic field sensor" is used to describe circuits that use magnetic field sensing elements, typically in combination with other circuits. Magnetic field sensors are used in a variety of applications, including, but not limited to, angle sensors that sense the angle of a magnetic field direction, current sensors that sense a magnetic field generated by a current carried by a current carrying conductor, magnetic switches that sense the proximity of a ferromagnetic object, rotation detectors that sense the passage of a ferromagnetic article, for example, through the magnetic domain of a ring magnet or the passage of a ferromagnetic target (e.g., a gear tooth) when the magnetic field sensor is used in combination with a reverse biased magnet or other magnets, and magnetic field sensors that sense the field density of a magnetic field.

[0012]

[0018] As used herein, the term "processor" or "controller" is used to describe an electronic circuit that performs a function, operation, or sequence of operations. The function, operation, or sequence of operations may be hard-coded into the electronic circuit or soft-coded by instructions held in a memory device. A "processor" may perform a function, operation, or sequence of operations using digital values ​​or using analog signals. In some embodiments, a "processor" may be embodied in an application specific integrated circuit (ASIC), which may be an analog ASIC or a digital ASIC. In some embodiments, a "processor" may be embodied in a microprocessor with associated program memory. In some embodiments, a "processor" may be embodied in a discrete electronic circuit, which may be analog or digital. A processor may include an internal processor or internal module that performs a portion of the processor's function, operation, or sequence of operations. Similarly, a module may include an internal processor or internal module that performs a portion of the module's function, operation, or sequence of operations.

[0013]

[0019] The electronic circuits shown in the figures herein may be shown in the form of analog or digital blocks, but it will be understood that the analog blocks can be replaced with digital blocks performing the same or similar functions, and that the digital blocks can be replaced with analog blocks performing the same or similar functions. Analog-to-digital or digital-to-analog conversion may not be explicitly shown in the figures, but will be readily understood by those skilled in the art.

[0014]

[0020] In particular, it should be understood that a so-called comparator may include an analog comparator having a two-state output signal indicating that an input signal is above or below a threshold level (or that one input signal is above or below another input signal). However, a comparator may also include a digital circuit having an output signal that includes at least two states that indicate that an input signal is above or below a threshold level, respectively (or that one input signal is above or below another input signal), or that indicates a digital value that is above or below a digital threshold (or another digital value), respectively.

[0015]

[0021] 1 shows a top view of a packaged current sensor integrated circuit 100. The package body 102 may be a molded body and is shown in outline for clarity.

[0016]

[0022] Primary conductor 130 has input and output portions which may each include a die attach portion 132, 134 that supports semiconductor die 108. Primary conductor 130 has input and output leads 136a, 136b on a first side of the package, 136c, 136d on a second side of the package, 138a, 138b on a third side of the package, and 138c, 138d on the second side of the package. Input leads 136a, 136b, 136c, 136d are connected to die attach pad 132 and output leads 138a, 138b, 138c, 138d are connected to die attach pad 134.

[0017]

[0023] The current sensor integrated circuit 100 further has secondary leads 120a, 120b, 120c, 120d, 120e. Wire bonds 140a, 140b, 140c, 140d, 140e, 140f connect the die 108 to the secondary, or signal, leads 120a, 120b, 120c, 120d, 120e. The secondary lead 120c is connected to the die 108 using two wire bonds 140c, 140e. This may be advantageous when potentials for higher currents may be present, such as for power or ground connections to the die 108.

[0018]

[0024] The primary conductor current path portion 133 may interconnect the die attach pads 132, 134 as shown and may be a narrowed portion. The primary conductor 130 has a partial current path that forms a straight line from a first side of the package including leads 136a, 136b across the package body to a third side of the package including leads 138a, 138b. The die 108 supports at least one magnetic field sensing element, in FIG. 1 two magnetic field sensing elements 109a, 109b. The die 108 may further support circuitry that amplifies and processes signals from the magnetic field sensing elements and provides an output for the current sensor integrated circuit 100. When a current flows through the current conductor portion 133, a magnetic field may be generated and sensed by the magnetic field sensing elements 109a, 109b. 1, the magnetic field sensing elements 109a, 109b are positioned away from or to the side of the current conductor portion 133 because the magnetic field generated by the current flowing in the current conductor portion 133 has a component perpendicular to the die such that an areal Hall effect sensor may be used for the magnetic field sensing elements 109a, 109b. In other embodiments, multiple magnetic field sensing elements or one magnetic field sensing element may be positioned directly above the primary current conductor portion to sense a magnetic field that includes a component parallel to the surface of the die 108. When the magnetic field component to be sensed is parallel to the surface of the die, a magnetoresistive element such as a vertical Hall element, GMR, TMR, or AMR element may be used.

[0019]

[0025] 1A, where like elements are labeled with like reference numbers, a side cross-sectional view of a packaged current sensor integrated circuit 100 is shown taken along line AA in FIG. 1. The package body 102 may have a recessed portion 104 around the bottom of the package. The die 108 is supported by a primary conductor die attach portion 132 having a thinned portion 132a. The die 108 may be attached to the die attach portion 132 by a non-conductive coating, such as a wafer backside coating (WBC), shown as two layers 110, 112. During manufacture, if two layers 110, 112 of wafer backside coating are used, the first wafer backside coating layer 110 is fully cured (or partially cured if only one layer of wafer backside coating is used), and then the second layer 112 of wafer backside coating is partially cured (also called B-stage curing) using which the die 108 can finally be attached to the die attach portion 132 of the primary conductor 130 of FIG. 1.

[0020]

[0026] In alternative embodiments, the die 108 may be attached to the die attach portion 132 by other materials, including, but not limited to, non-conductive die attach epoxies or tapes. Multiple layers of wafer backside coatings, tapes, and non-conductive epoxies may be used for electrical insulation. A combination of wafer backside coatings, tapes, or non-conductive epoxies may be used to achieve electrical insulation and attachment to the die attach portion 132.

[0021]

[0027] The die 108 may be electrically connected to the secondary lead 120b using wire bonds 140. The secondary lead 120b may have a recessed portion 122 and / or a thinned portion 124 that provides a locking mechanism with the molded body 102. The thinned portion 124 may be the result of a half etchi lead frame process. An example of a half etch process is when a lead frame is etched from two sides and one etched side is masked or patterned such that a partial thickness (or approximately half) of the lead frame remains with a portion of the lead or lead frame. The package body 102 and secondary lead 102b may have a cutout or recessed portion 104 that may be around the entire bottom edge of the packaged current sensor integrated circuit 100 in an embodiment.

[0022]

[0028] 1B, where like elements are labeled with like reference numerals, a bottom view of packaged current sensor integrated circuit 100 is shown. Secondary leads 120a, 120b, 120c, 120d, 120e have portions exposed on the bottom of package 100. Primary current conductor 130 is shown with die attach portions 132, 134, current conductor portion 133, and at least a portion of leads 136a, 136b, 136c, 136d, 138a, 138b, 138c, 138d exposed on the bottom of package 100. In use, exposed portions of die attach pads 132, 134 may be connected to a circuit board or other substrate, and because there may potentially be a larger area connection between the circuit board and primary conductor 130, the connection resistance may be lower, resulting in lower power loss due to the connection resistance of current sensor package 100 to the circuit board. In another embodiment, a solder connection may also be provided with current conductor portion 133. If the solder connection or current path is directly under area 133, the accuracy of the current sensor IC may be improved when the gain of the current sensor integrated circuit is programmed with the current path of current conductor portion 133 in parallel with the solder and PC board conductors.

[0023]

[0029] 1C, where like elements are labeled with like reference numerals, a side view of the packaged current sensor integrated circuit 100 is shown. The primary conductor input / output leads 138a, 138b and the signal, i.e., secondary lead 120e are exposed and are approximately flush with the plastic of the package body 102. The distance between the secondary lead 120e and the primary lead 138a is selected to meet the electrical insulation requirements of the application. In an embodiment, the spacing from the primary lead to the secondary lead is at least 1.0 mm on the surface, or outside, or on the package, allowing for a voltage insulation rating of 100V.

[0024]

[0030] A recessed portion 104 of the package body 102 and leads 138a, 138b, 120e are shown around the bottom edge of the package. This recessed portion 104 may be used when the packaged current sensor integrated circuit 100 is assembled to a printed circuit board or other assembly to allow inspection or probing of the solder connections between the package 100 and the PC board or assembly.

[0025]

[0031] In an embodiment, the primary conductor 130 and secondary leads 120a-e may have a thickness on the order of 0.2 mm to 0.5 mm. In another embodiment, the primary and secondary leads have a thickness of 0.375 mm, possibly ranging from 0.35 to 0.40 mm, which is thicker than a standard integrated circuit package, although the standard thickness may be on the order of 0.2 mm-0.25 mm + / - 0.025 mm for manufacturing tolerances. The thicker primary conductor serves to increase the cross-sectional area perpendicular to the current flow. The increased thickness of the current conductor material of the primary conductor 130 and current path portion 133 reduces power loss in a system utilizing the current sensor package 100 of FIG. 1.

[0026]

[0032] As noted above, the recessed portion 104 of the package body 102 can facilitate testing of the packaged current sensor integrated circuit 100 once in use (e.g., soldered to a circuit board). Thanks to the configuration of the primary conductor leads 136a-136d, 138a-138d, such testing can be done from three sides of the packaged circuit 100. Leads 136a, 136b, and 136c, 136d of the primary conductor 130 allow testing of the solder on adjacent sides of the package that are substantially orthogonal to one another as shown in Figures 1 and 1B. Similarly, leads 138a, 138b, and 138c, 138d allow testing of the solder on adjacent sides of the package that are substantially orthogonal to one another. Leads 136c, 136d, and 138c, 138d are on the same side of the package 100.

[0027]

[0033] In another embodiment, the lead frame thickness may be a standard lead frame thickness. The primary current planned to be sensed by the current sensor package 100 or the absolute resistance required by the application can determine the required lead frame thickness.

[0028]

[0034] 2, there is shown an example circuit block diagram for an integrated circuit 200 that may be present on the die 108 of FIG. p290 passes through the current conductor portion 233 (which may be the same as or similar to the primary conductor 130 in FIG. 1) to generate a magnetic field B 295. The magnetic field B 295 includes a component that rises into the die at the magnetic field sensing element 209b and falls into the magnetic field sensing element 209a (according to the right-hand rule) for a current flowing from top to bottom in FIG. 2 when the current conductor portion 233 is below the die 200. The magnetic field sensing elements 209a, 209b may be, for example, planar Hall effect plates. The magnetic field 295 causes the Hall effect plates 209a, 209b to provide a signal to the front-end amplifier 250. The front-end amplifier 250 provides an output to the amplifier 254, which may be a linear amplifier, and the output is fed into the output circuit 256. The output circuit 256 may be a digital or analog circuit that provides an output to at least one bond pad, or to two bond pads 220d, 220e as shown in FIG. 2. Output bond pad 220e may be a linear output representative of the magnetic field 295 measured and amplified through amplifier 254. Several other output bond pads, three or more, may also be provided. In an alternative embodiment, amplifier 254 may provide an output directly to bond pad 220e. Output bond pad 220d may be a fault output representative of a fault condition of the current sensor integrated circuit package.

[0029]

[0035] Bond pad 220a provides a voltage and current input, typically Vcc, to supply power to integrated circuit 200. Ground bond pad 220c is provided to integrated circuit 200. In another embodiment, the voltage level provided at bond pad 220c may be other than ground voltage, or a voltage above or below ground voltage as a reference voltage to integrated circuit 200. Input bond pad 220a is coupled to a master current supply circuit 260 that supplies power to the circuitry within integrated circuit 200. Although master current supply 260 is provided as a current supply, it will be apparent that a voltage may also be supplied to the circuitry on integrated circuit 200. Hall effect current driver circuit 262 draws current (or voltage) from master current supply 260 and supplies a regulated current to Hall effect sensing elements 209a, 209b. Master current supply 260 also supplies power to power-on reset circuit 270. The power-on reset circuit monitors the power coming into the circuit 200 and provides a signal to an EEPROM and control logic circuit 272. The power-on reset circuit 270 as well as the EEPROM and control logic circuit 272 are used to configure and enable the integrated circuit including the output circuit 256.

[0030]

[0036] The EEPROM and control logic circuit 272 provides a signal to a sensitivity control circuit 274, which provides a signal to the front-end amplifier 250 to adjust the sensitivity of the front-end amplifier. The adjustment may be the result of a change in power level in the circuit 200, or may be the result of a change in temperature of the circuit 200. A temperature sensor circuit is not shown in FIG. 2. Examples of a temperature sensor circuit may include, but are not limited to, a diode temperature sensor, or the use of a known temperature compensated resistor.

[0031]

[0037] EEPROM and control circuit 272 provides a signal to offset control circuit 276. Offset control circuit 276 provides a signal to amplifier 254. Offset control circuit 276 allows circuit 200 to adjust the offset of amplifier 254 for changes in power or temperature, or a combination of temperature and power changes (temperature compensation circuitry not shown). Offset control circuit 276 can also adjust for other sources of offset, such as stress on the integrated circuit die.

[0032]

[0038] In alternative embodiments, the EEPROM in EEPROM and control circuitry 272 may be replaced with another type of memory or may be used in combination with another type of non-volatile memory, including, but not limited to, metal or polysilicon fuses, flash memory, or MRAM.

[0033]

[0039] The input lead 220b may be provided to set a threshold (i.e., provide a fault trip level) for the fault indication circuit 280. In an embodiment, the input lead 220b provides a fault voltage level. The fault indication circuit 280 comprises a threshold circuit 282 and a fault comparator 284. The EEPROM and control circuit 272 provides an input to the threshold circuit 282. The threshold circuit 282 provides a signal to the fault comparator 284, which compares the output of the threshold circuit 282 with the output of the front-end amplifier 250 to notify the output circuit block 256 when a fault exists. The output circuit generates a fault output at the output bond pad 220d. The fault output may indicate an overcurrent condition, in which the current sensed in the current conductor path 233 exceeds a fault trip level, which may be provided in the form of a fault voltage level on the bond pad 220b. In one example, a fault may allow a user of the current sensor package 100 of FIG. 1 to stop the current in the primary current path to prevent a high current condition in the electrical circuit connected to the primary conductor 130 of FIG. 1.

[0034]

[0040] In an embodiment, the function of the fault indication circuit 280 may be performed in a digital circuit or digital processor. The comparison to the fault trip level may include an analog-to-digital circuit (ADC) in front of the digital logic circuit, which may include a processor or microprocessor circuit that compares the fault trip level voltage with the voltage provided by the front-end amplifier and ADC circuit to convert the analog voltage of the front-end amplifier 250 to a digital voltage. In an embodiment, the amplifier 250 may be a buffer amplifier with a gain close to or equal to unity (or one). In another embodiment, the amplifier 254 may provide a non-unity gain.

[0035]

[0041] In an embodiment, a multiplexing circuit may be used to allow the same ADC to be used for the output of the front-end amplifier circuit 250 and the fault trip level voltage. It will be apparent to one skilled in the art that other circuits, such as timing circuits and sample and hold circuits, may be used to implement a multiplexed digital circuit.

[0036]

[0042] FIG. 3 shows a top view of a packaged current sensor integrated circuit 300 that can be manufactured with a small package body, for example, the package has a molded package body top view dimension of approximately 2.98 mm×1.95 mm and a thickness of 1.00 mm. The package body 302 can be a molded body and is shown as an outline for clarity. The current sensor integrated circuit 300 of FIG. 3 uses a thinner lead frame material than other integrated circuit sensors, which can reduce package dimensions. By using a smaller package, the current sensor integrated circuit of FIG. 3 can require less space when assembled or used on a board, circuit assembly, or module. The thinner package can enable the package to have greater vibration resistance compared to a thicker molded package body. A standard SOIC-8 style package can have a size of approximately 4.9 mm×3.9 mm×1.47 mm. An industry standard SOT23 package can have a size of approximately 2.90 mm×1.60 mm×1.15 mm. Although the length and width of the described package are larger than the standard SOT23 package, in the described package the package thickness can be reduced from 1.15 mm for the standard SOT23 to 1.00 mm or less, thereby increasing the vibration resistance or reducing the effects of mechanical vibrations in current sensor applications.

[0037]

[0043] Primary conductor 330 has input and output portions and includes an input lead 336, an output lead 338, and die attach portions 332, 334 that support semiconductor die 308. Primary conductor 330 has input lead 336 and output lead 338 on a first side of the package. Input lead 336 is connected to die attach pad 332 and output lead 338 is connected to die attach pad 334.

[0038]

[0044] The current sensor integrated circuit 300 also has secondary leads 320a, 320b, 320c. Wire bonds 340a, 340b, 340c connect the die 308 to the secondary, or signal, leads 320a, 320b, 320c. In an embodiment, a low loop height wire bond process may be used to allow for a reduced package body thickness.

[0039]

[0045] The current path 395 of the primary conductor lead frame includes the input lead 336 of the primary conductor 330, the die attach portion 332, the current conductor portion 333, the die attach portion 334, and the output lead 338. The current conductor portion 333 connects the die attach pads 332, 334 and may be a narrowed portion as shown in FIG. 3. The die 308 supports two magnetic field sensing elements 309a, 309b. The die 308 may further support circuitry for amplifying and processing signals from the magnetic field sensing elements and providing an output of the current sensor integrated circuit 300. When a current flows through the current conductor portion 333, a magnetic field may be generated and sensed by the magnetic field sensing elements 309a, 309b. 3, for example, a planar Hall effect sensor may be used for the magnetic field sensing elements 309a, 309b, such that the magnetic field generated by the current flowing in the current conductor portion 333 has a component perpendicular to the die 308 in the area where the magnetic field sensing elements 309a, 309b are located, the magnetic field sensing elements 309a, 309b are located on the die 308 and on the side of the current conductor portion 333. In other embodiments, multiple magnetic field sensing elements or one magnetic field sensing element may be located directly above the primary current conductor portion to sense a magnetic field that includes a component parallel to the surface of the die 308. When the magnetic field component to be sensed is parallel to the surface of the die, a vertical Hall effect element or a magnetoresistive element such as a GMR, TMR, or AMR element may be used.

[0040]

[0046] The use of two magnetic field sensing elements 309a, 309b allows for improved stray magnetic field immunity and helps reduce the impact of external magnetic fields on the current sensor integrated circuit 300. For example, for a current flowing as indicated by arrow 395, from left to right across the figure, from input lead 336 to output lead 338, the magnetic field emanating from the page is observed by sensing element 309a, and the magnetic field entering the page is observed by the sensing element in area 309b. A summing circuit may be used to calculate a magnetic field proportional to the current flowing in the current conductor portion 333. The sensing elements 309a, 309b may be positioned or biased such that any stray or common external magnetic field has the effect of one sensing element 309a being positive and the other sensing element 309b being negative, such that when summed, the external magnetic fields cancel, but the expected magnetic field generated by the current in the primary conductor has a value that is twice as high as, for example, the value from either magnetic sensing element.

[0041]

[0047] Other magnetic field sensing elements, such as vertical Hall, GMR, or one or more TMR magnetic field sensing elements, may be placed directly above the current conductor portion 333 of FIG. 3. The TMR, GMR, or vertical Hall element may be used to measure magnetic flux in a direction approximately parallel to the surface of the die 308, which is the direction of the magnetic flux generated by the current in the primary conductor, directly above the current conductor portion 333. A second vertical Hall, GMR, TMR magnetic field sensing element may also be placed directly above the current conductor portion 333. Other combinations of magnetic field sensing elements, including but not limited to areal Hall, vertical Hall, GMR, TMR, or AMR, may be placed in the area to the side of the current conductor portion 333 or in the area directly above the current conductor portion 333. The placement of the magnetic field sensing elements will be determined in part by the axis of greatest sensitivity of the selected type of magnetic field sensing element; for example, planar holes will have their axis of greatest sensitivity perpendicular to the face of the die 308, while vertical holes, GMR, TMR, and AMR elements will have their axis of greatest sensitivity parallel to the surface of the die 308.

[0042]

[0048] In another embodiment, there may be only one magnetic field sensing element on the die 308 located at the location of element 309a or 309b or located directly above the current conductor portion 333. In another embodiment, there may be more magnetic field sensing elements. For example, elements 309a, 309b may include multiple Hall elements, including but not limited to multiple dual Hall effect elements or multiple quad Hall effect elements. Multiple magnetic field sensing elements may be on only one side of the current conductor portion 333 or directly above the current conductor portion 333. In an embodiment, there may be only one magnetic field sensing element 309a or 309b or directly above the current conductor portion 333 and multiple magnetic field sensing elements at another location or directly above the current conductor portion 333.

[0043]

[0049] FIG. 3A illustrates a side view of the current sensor integrated circuit 300 of FIG. 3 along line A-A' of FIG. 3. The thinner leadframe thickness allows for a thinner or reduced molded package thickness 350. The reduced molded body package thickness 350 allows for improved mechanical vibration performance when the current sensor integrated circuit package 300 is assembled onto, for example, a circuit board. In an embodiment, the package thickness 350 is less than 1.0 mm. In another embodiment, the package thickness has a range of 0.95 to 0.98 mm. In an embodiment, the leadframe thickness 331 is nominally 150 microns, or 6 mils thick.

[0044]

[0050] In an embodiment, the current sensor integrated circuit 300 of Figures 3 and 3A may use a leadframe material thickness 331 of about 150 microns, or 6 mils, or a thinner leadframe material. The leadframe thickness 331 may vary with manufacturing tolerances between 5 mils and 7 mils, or approximately 125 microns and 175 microns (approximately 0.125 mm to 0.175 mm). In another embodiment, the leadframe thickness may vary between 0.140 mm and 0.162 mm. For example, a standard leadframe thickness for a SOIC-8 style current sensor package may be a nominal 200 microns, or 8 mils, in the range of 190 to 210 microns.

[0045]

[0051] To achieve 300V dielectric isolation, the distance between the primary conductor 330 and the signal leads 320a, 320b, 320c should be nominally 0.160 mm, or about 6.4 mils, with a minimum distance, including manufacturing tolerances, of at least 0.125 mm, or about 5 mils. In an embodiment, the secondary leads 320a, 320b, 320c are provided on a second, opposite side of the package body from the primary input lead 336 and the primary output lead 338.

[0046]

[0052] The die 308 is supported by primary conductor die attach portions 332, 334. The die 308 may be attached to the die attach portions 332, 334 by a non-conductive coating, such as the wafer backside coating (WBC) shown in FIG. 1A, which may be two layers. During manufacture, if two layers of wafer backside coating are used, the first wafer backside coating layer is fully cured (or partially cured if only one layer of wafer backside coating is used), and then the second layer of wafer backside coating is partially cured (also called B-stage curing) with which the die 308 can finally be attached to the die attach portions 332, 334 of the primary conductor 330 in FIG.

[0047]

[0053] In alternative embodiments, the die 308 may be attached to the die attach portion 332, 334 by other materials, including, but not limited to, non-conductive die attach epoxy or tape. Multiple layers of wafer backside coating, tape, and non-conductive epoxy may be used for electrical isolation. A combination of wafer backside coating, tape, or non-conductive epoxy may be used to achieve electrical isolation and attachment to the die attach portion 332.

[0048]

[0054] In an embodiment, the primary conductor 330 may include chamfered, contoured, or shaped conductor regions 358a, 358b, 358c, 358d between the die attach portions 332, 334 and the current conductor portion 333. In an embodiment, the chamfer may have a radius of approximately 0.20 mm or greater. In an embodiment, the chamfer dimension is between 0.18 mm and 0.30 mm. The shaped conductor regions 358a, 358b, 358c, 358d change the current flow in the primary conductor 330 such that the magnetic field generated by the current flow in the primary conductor is more uniform near the magnetic field sensing elements 309a, 309b or directly above the current conductor portion 333 of the primary conductor 330. The more elongated, shaped conductor regions 358a, 358b, 358c, 358d provide a reduction in error in the measured current in the primary conductor portion 333, thereby enabling the current sensor to achieve more accurate current measurements. In an embodiment, the distance from die attach portion 332 to 334, shown as dimension 352, including shaped conductor regions 358a, 358b, 358c, 358d and current conductor portion 333, is approximately 0.60 mm, and in an embodiment, is between 0.50 mm and 0.70 mm.

[0049]

[0055] The primary conductor 330 may include mechanical locking features 355a, 355b that function to improve the moisture sensitivity level (MSL) performance of the package, which is important for reliability. The mechanical locking features 355a, 355b are positioned such that the nearest edges 357a, 357b of the mechanical locking features 355a, 355b are positioned such that there is a space 353a, 353b between the primary input and output leads 336, 338 and the die attach portion edges 351a, 351b adjacent to the nearest edges 357a, 357b of the mechanical locking features 355a, 355b. Any material removed from the primary conductor 330 may lead to an increase in resistance. By locating the mechanical locking features 355a, 355b outside of the primary current path 395, the increase in resistance of the primary conductor 330 is reduced. If a hole or holes were made in the primary conductor near the input lead 336 and / or output lead 338, the electrical resistance of the primary conductor 330 would increase since there would be less leadframe material for the current to flow through. The spacing 353a, 353b allows more leadframe material to remain intact in the primary current path 395, thereby maintaining a lower resistance of the primary conductor as measured from the input and output leads 336, 338 caused by removing leadframe material to form the mechanical locking features 355a, 355b. In an embodiment, the mechanical locking features 355a, 355b have a semicircular shape with a radius of 0.15 mm to 0.25 mm. In an embodiment, the radius of the mechanical locking features 355a, 355b is nominally 0.20 mm. Die attach portion edges 351a, 351b are 0.2 mm inside package body 302 and spacing 353a, 353b is at least 0.4 mm. In an embodiment, spacing 353a, 353b is between 0.4 mm and 0.6 mm. In an embodiment, spacing 353a, 353b is nominally 0.50 mm. In another embodiment, mechanical locking mechanisms 355a, 355b may have spacing 353a, 353b of 0.0 mm.The shape of the mechanical locking mechanism may be other than semicircular, including but not limited to a hole in the primary conductor, a rectangular cutout, or a triangular cutout.

[0050]

[0056] The current sensor integrated circuit 300 may have a circuit similar to that shown in FIG. 2. The three signal leads 320a, 320b, 320c for the current sensor integrated circuit 300 may be a Vcc, an input voltage or power pin or lead, an output pin or lead, and a ground or reference pin or lead. The current sensor integrated circuit 300 may have an output protocol circuit to provide an output protocol at the output lead or pin, which may allow more data to be transmitted from a single pin or output lead. In another embodiment, a two-wire output may be used, where data is transmitted by changes in current provided at the Vcc or ground voltage lead.

[0051]

[0057] It is understood that any of the above processes may be implemented in hardware, firmware, software, or a combination thereof. The processes may be implemented in a computer program executed on a programmable computer / machine, each of which includes a processor, a processor-readable storage medium or other article of manufacture (including volatile and non-volatile memory and / or storage elements), at least one input device, and one or more output devices. The program code may be applied to data entered using the input device to perform the process and generate output information.

[0052]

[0058] Having described exemplary embodiments of the present disclosure, it will now be apparent to one of ordinary skill in the art that other embodiments incorporating their concepts may also be used. The embodiments contained herein should not be limited to the disclosed embodiments, but rather should be limited only by the spirit and scope of the appended claims. All publications and references mentioned herein are expressly incorporated herein by reference in their entirety.

[0053]

[0059] Elements of different embodiments described herein may be combined to form other embodiments not specifically described above. Various elements 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.

Claims

1. a primary conductor having input and output leads, a first die attach portion, a second die attach portion, and a current conductor portion between the first die attach portion and the second die attach portion, the primary conductor configured to pass current from the input lead through the first die attach portion, the current conductor portion, the second die attach portion, to the output lead, at least one of the first die attach portion and the second die attach portion having a die attach portion edge adjacent a respective one of the input leads or the output leads; a mechanical locking mechanism spaced from the die attach portion edge; at least one secondary lead; a semiconductor die supported by the first die attach portion and the second die attach portion; at least one magnetic field sensing element supported by the semiconductor die, the at least one magnetic field sensing element being disposed adjacent to the current conductor portion; a package body enclosing the semiconductor die and at least a portion of the primary conductor, the input lead and the output lead extending from a first side of the package body and the at least one secondary lead extending from a second side of the package body opposite the first side of the package body; 1. A packaged current sensor integrated circuit comprising:

2. The packaged current sensor integrated circuit of claim 1 further comprising at least three secondary leads.

3. 3. The packaged current sensor integrated circuit of claim 2, wherein at least one secondary lead provides an output connection, at least one secondary lead provides a voltage input connection, and at least one secondary lead provides a ground connection.

4. The packaged current sensor integrated circuit of claim 1 further comprising a front-end amplifier, the at least one magnetic field sensing element being connected to the front-end amplifier.

5. The packaged current sensor integrated circuit of claim 1 , wherein the at least one magnetic field sensing element is a Hall Effect sensor.

6. 6. The packaged current sensor integrated circuit of claim 5, further comprising a Hall effect current drive circuit connected to said Hall effect sensor.

7. The packaged current sensor integrated circuit of claim 5 , wherein the Hall effect sensor is disposed adjacent the current conductor portion of the primary conductor.

8. 8. The packaged current sensor integrated circuit of claim 7, wherein the at least one magnetic field sensing element includes a first Hall effect sensor disposed adjacent a first side of the current conductor portion, and the packaged current sensor integrated circuit further includes a second Hall effect sensor disposed adjacent a second side of the current conductor portion opposite the first side.

9. 10. The packaged current sensor integrated circuit of claim 1, wherein a front-end amplifier is connected to the amplifier for providing an output of a current level in the primary conductor.

10. 10. The packaged current sensor integrated circuit of claim 1 further comprising a wafer backside coating material on a backside of said semiconductor die.

11. The packaged current sensor integrated circuit of claim 10 further comprising a second wafer backside coating material on the backside of the semiconductor die.

12. 10. The packaged current sensor integrated circuit of claim 1, wherein the distance between the primary conductor lead frame and the at least one secondary lead frame is at least 0.125 mm.

13. 2. The packaged current sensor integrated circuit of claim 1, wherein the mechanical locking mechanism is spaced from the die attach edge portion by at least 0.50 mm.

14. 10. The packaged current sensor integrated circuit of claim 1, wherein the primary conductor has a current conductor portion of the primary conductor defining a conductor area.

15. The packaged current sensor integrated circuit of claim 1 , wherein the package body has a thickness of less than 1.0 mm.

16. 10. The packaged current sensor integrated circuit of claim 1, wherein the primary conductor lead frame has a thickness between 0.140 mm and 0.162 mm.

17. 1. A method for sensing current in a current sensor integrated circuit package, comprising: providing a primary conductor having input and output leads, a first die attach portion, a second die attach portion, and a primary conductor portion, the primary conductor configured to conduct current from the input lead through the first die attach portion, the primary conductor portion, the second die attach portion, and the output lead; providing a mechanical locking mechanism within the primary conductor spaced from a die attach portion edge; providing at least one secondary lead; providing a semiconductor die disposed adjacent to the primary conductor; providing at least one magnetic field sensing element supported by the semiconductor die, the at least one magnetic field sensing element being disposed proximate the primary conductor portion; providing an output signal representative of current in the primary conductor; The method according to claim 1,

18. 20. The method of sensing current in a current sensor integrated circuit package of claim 17, wherein the at least one magnetic field sensing element includes a first magnetic field sensing element disposed adjacent a first side of a current conductor portion, the method further including the step of providing a second magnetic field sensing element disposed adjacent a second side of the current conductor portion opposite the first side.

19. 20. The method of sensing current in a current sensor integrated circuit package of claim 17, wherein the magnetic field sensing element is one of a planar Hall effect element, a vertical Hall effect element, an anisotropic magnetoresistance (amr) element, a giant magnetoresistance (gmr) element, or a tunneling magnetoresistance (tmr) element.

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