Abstract:
An apparatus including an integrated circuit device comprising a plurality of pins, a plurality of electrostatic discharge units individually coupled to respective ones of the plurality of pins, and a portion of the plurality of electrostatic discharge units configured, upon addressing, to generate a signal representing a signature of the integrated circuit device. A method including for a plurality of suppliers of a similar integrated circuit device, the integrated circuit device comprising a plurality of pins and a plurality of electrostatic discharge units individually coupled to respective ones of a portion of the plurality of pins, and assigning an output value representative of the supplier to an addressing of the plurality of electrostatic discharge units.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to integrated circuit testing. 
     2. Background 
     In the assembly of component parts (devices) from various suppliers in a package, such as a motherboard of a processor, such parts are generally inventoried, subjected to a quality assurance analysis for fitness, staged in readiness, and assembled into the package. The package is then tested for fitness, both through visual inspections and circuit testing. The visual inspection may involved, for example, a visual confirmation that the correct part is located in the correct place. The circuit testing generally device values (e.g., through current, resistance, capacitance, etc.) component orientation, and circuit content. It is appreciated that in the assembly of a package, it is desirous that the correct and capable part is installed in the package. 
     Many component parts of a scale of less than four microns (μm) include an I 2 C bus and associated registers. The I 2 C bus was developed by Philips Semiconductor of Sunnyvale, California. The electrical fitness of a part (device) with an associated I 2 C bus and register may be evaluated through such circuitry. 
     Generally larger (about 4 μm or greater) legacy technology necessary, for example, for handling high power conversion applications typically do not contain I 2 C bus technology and the increase pin count associated with such technology is not cost effective to incorporate. Accordingly, what is needed is an alternative for electrically verifying the fitness of a component part (device) that is compatible with larger scale components. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The features, aspects, and advantages of the invention will become more thoroughly apparent from the following detailed description, appended claims, and accompanying drawings in which: 
     FIG. 1 shows a schematic representation of an ESD device protection system on a part (device). 
     FIG. 2 shows a schematic representation of a part (device) having external pins suitable for mounting on a package and an assigned signature according to an embodiment of the invention. 
     FIG. 3 shows a process flow of establishing and identifying a signature of a party (device) in accordance with an embodiment of the invention. 
    
    
     DETAILED DESCRIPTION 
     In general, most component parts designed for assembly on a package such as a printed circuit board including a motherboard of a processor incorporate a coupling technology to electrically couple the part (IC) to the package. Typically, particularly with larger technologies (on the order of 4 μm or more) such coupling technology includes an array of pins. Such pins include power and ground pins as well as pins to carry electrical information (signals) to and from the part (IC). 
     To protect the devices of a part (IC) from errant electrical signals, particularly triboelectricity in the form of electrostatic discharge (ESD), manufactures generally include on the pins of the part (IC) a protection device such as an ESD device. An ESD device coupled to ground is designed to act in the presence of a high voltage event at the pin to bring the associated current to ground rather than exposing such event to the part (IC). The typical ESD device is the diode, including a diode connected transistor (e.g., NPN transistor), with one diode from device ground to the device pin. 
     FIG. 1 shows a typical configuration of a part (IC) with an ESD device. Assembly  100  includes part (IC)  130  having pin  110  (typically a plurality of pins) for coupling part (IC)  130  to a package. Between part (device)  130  and pin  110  is ESD device  120 . With this configuration, a high voltage event at pin  110  will get diverted from part (device)  130  to ESD device  120  and to ground. 
     According to one embodiment, an ESD device or devices of a part (IC) such as an integrated circuit chip on a package, including a motherboard are utilized as a representation of the type of part (IC) and/or the supplier of the part (IC). In one example, a signal generated by an ESD device or devices upon addressing represents a signature of the part (IC) such as the type of part (IC) or the manufacturer or supplier of the part (IC). 
     In another embodiment, a method of identifying an integrated circuit part (IC) is disclosed. The identification includes addressing an ESD device or devices on the part (IC), generating an output signal from the ESD device or devices, and identifying the part (IC) by the output signal. 
     FIG. 2 is a schematic illustration of a part (IC) configured with an electrical signature according to an embodiment of the invention. FIG. 2 shows part (IC)  200  such as an integrated circuit chip suitable for placement on a package such as a printed circuit board (e.g., a motherboard). In one embodiment, part (IC)  200  has a footprint on the order of 4 μm or greater. Examples include, but are not limited to, typical power conversion units such as field effect transistor (FET) drivers, FET controllers, and low drop out (LDO) voltage regulators. Part  200  may have several pins that are configured to communicate with a printed circuit board. FIG. 2 illustrates four representative pins  210 ,  220 ,  230 , and  240 . Each of the four pins has or is associated with part (device)  200  by at least one ESD device  215 . ESD device  215  may be, for example, a diode, including but not limited to, a diode-connected NPN transistor. 
     FIG. 2 shows a pin array (four pins) with an alternating number of ESD devices (e.g., diodes) on each of the pins of the array. Pin  210  has a single ESD device (ESD device  215 ). Pin  220  has two ESD devices. Pin  230  has a single ESD device. Pin  240  has two ESD devices. 
     In one example, part (IC)  200  is an FET driver available from more than one manufacturer. It may be desirable, in the context of evaluating part (IC)  200 , such as during ICT, to identify that part (IC)  200  is an FET driver and/or the manufacturer of part (IC)  200 . By requiring that manufacturers of FET drivers conform to a predetermined or assigned ESD device configuration associated with a selected number of pins, part (IC)  200  can be evaluated for fitness. Thus, electrically addressing the selected number of pins (pins  210 ,  220 ,  230 , and  240 ) by, in the case of a diode, forcing a current from ground to pin, an electrical signature may be measured identifying the part (IC) as an FET driver and/or the manufacturer of the part (IC). In one embodiment, a pseudo binary value may be assigned to an electrical output. For example, where the ESD devices are diodes, a signal output of, for example, 0.7 volts represents a single diode and is assigned a binary value of “0”. A signal output of 1.4 volts represents two diodes and is assigned a binary value of “1”. Thus, depending on the number of pins representing a signature, a binary representation of part (IC)  200  can be established. 
     It is to be appreciated that any number of ESD devices may be used for a desired signature. For example, where the objective is to electrically identify one of two manufacturers of a part (IC), a single ESD device such as ESD device  210 , the two manufacturers may be individually identified by whether the output of ESD device  210  is represented as a “0” or a “1”. 
     FIG. 3 is representation of a process flow of carrying out an identification of a part (IC). FIG. 3 presents a process flow to electrically address and identify a part (IC) on a package utilizing ESD devices, such as ESD diodes, coupled to pins of a part (IC). Process flow  300  begins by assigning an ESD device pattern to a predetermined number of pin-coupled ESD devices (block  310 ). In the case of a manufacturer or manufacturers of a single part (IC), the assignment may involve an assignment representative of the type of part (IC) and/or the manufacturer. 
     Once the ESD device pattern is assigned, the part (IC) is installed on the package such as on a printed circuit board, including but not limited to a motherboard (block  320 ). As part of, for example, ICT testing, the part (IC) is electrically evaluated for a signature. In the case of an ESD diode or diodes coupled to external pins of the part (IC), this is achieved by forcing a current through the assigned ESD devices (block  330 ). The corresponding voltage (e.g., forward conduction voltage) is sensed (e.g., measured) (block  340 ) and a pseudo-binary value is assigned to each output (block  350 ). Based on the pseudo-binary value measured, an electrical signature of the part (IC) is provided. Such a signature may be used to, among other things, verify the supplier of the part (IC) and/or verify that the correct part (IC) is placed on the package (block  360 ). 
     The placing of an identifier within an ESD device allows the ESD device configuration to be used as a signature of a part (IC). By electrically addressing and identifying a signature, the possibility of placing the incorrect part (IC) (either type or manufacturer) on a package may be reduced. Thus, the technique may be used to enhance wrong-part detection by electronic methods. 
     In the foregoing specification, the invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.