Tham khảo tài liệu 'adaptive techniques for dynamic processor optimization theory and practice episode 2 part 8', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Chapter 12 The Challenges of Testing Adaptive Designs 293 During wafer sort where bare die is tested the on-package band-gap reference is not available and the band-gap reference is replaced by a fixed voltage. Firmware is loaded into the microcontroller to evaluate the linearity and gain of the voltage VCO count table. In Figure this process is shown using both a good and a bad part. Figure Process for evaluating VCO table. For the bad part an increase in voltage from to caused a decrease in VCO count from 21391 to 21389. This behavior would cause the count 21390 to make to both and making voltage measurement far too inaccurate to measure power accurately. With the testing of the VCO complete the on-package parasitic resistance can be measured. If the resistance is too low not enough voltage delta will be generated under load to get an accurate power measurement. If the resistance is too high significant power is wasted in the package itself. By measuring the voltage drop across the connector Vc1-Vd1 using the VCO while the chip is idle and consuming standby current I0 and then measuring the voltage drop Vc2-Vd2 while the chip is under a known additional current load IDelta the package resistance can be computed using a simple formula Figure . This formula once again is applied using special firmware in the microcontroller and the range is tested to be within acceptable limits Figure . 294 Eric Fetzer Jason Stinson Brian Cherkauer Steve Poehlman Current Figure Graphical representation of Rpkg measurement. IEEE 2006 Compute Rpackage Test Range Min Package MclX ỈDeìtĩt Figure Computation and test of Rpkg. Test Passed Power Measurement Impacts on Other Testing During operation the package resistance is not a constant. As package temperature increases so does the resistance of the package. The temperature of the processor is a function of processor activity and ambient temperature of the system. As a
