application note 1 of 10 www.xicor.com AN143 x3100 voltage measurement accuracy description this test measures the accuracy of the celll voltage measurement circuits of the x3100. in the test, a known voltage is applied across each cell input of the x3100. the analog output voltage of the x3100 is measured for each cell. this value is compared to the input voltage. the collected data includes the values from three devices from three different lots. the data also includes tests at 0 o c, 25 o c and 50 o c. test setup for this test, vcc was held at 16v to prevent the device entering the sleep mode when testing cell voltages below 2v. in the test 4v was applied to all cells, except the cell being measured. the voltage was applied at 10mv inter- vals over four ranges. these input ranges were 1.5 to 1.7v, 2.5 to 2.7v, 3.5 to 3.7v and 4.0 to 4.2v. figure 1. cell voltage measurement for each cell and each applied voltage the output was recorded. this involves the changing of the analog multiplexer setting in the x3100. in gathering the data with this test, the output was sample. this procedure was used to reduce the effect of external noise on the test environment. results the data for this test is available in raw form in an excel spreadsheet. this spreadsheet includes data for each device, data for each lot, and data for all devices. each set of data includes results for the three temperature settings and the four gain settings. the data was copied to other ?les for the purposes of generating graphs. the result summaries show the output error as a percentage. this error is provided for each of 3 lots as well as the combined data. data is averaged, and stan- dard deviation computed, from samples taken at three temperatures 0 o c, 25 o c and 50 o c. on the following charts, absolute error is the output minus the input, while the percent error is calculated as follows: overall performance the following set of graphs shows the performance of the x3100 over temperature and across three lots of three devices. the graphs will show the basic input/ output curve, raw error, and error after correction for offset and gain. the below data shows that the x3100 output is accurate, with 3 standard deviations, to better than 2.5% error across all measured voltages. it also shows that over the key range of 2.5 to 4.2v, accuracies of better than 1% can be expected. these accuracies are not dependent on any calibration factors. x3100 + + + + 16v ao vcell1 vcell2 vcell3 vcell4 vss error output input C input -------------------------------------- =
2 of 10 AN143 application note www.xicor.com figure 2. characterization test setup hp6626 power supply x3100 + - + - + - + - vcell1 vcell2 vcell3 vcell4 vss keithley 236 source measurement unit hp6626 power supply keithley 2002 dmm vcc vrgp vrgc vrgo keithley 2000 dmm ao pc spi serial analog select vcs1 vcs2 20.37 ohm
3 of 10 AN143 application note www.xicor.com lot 1 1. input to output voltage error - cell 1 2. input to output voltage error - cell 2.
4 of 10 AN143 application note www.xicor.com 3. input to output voltage error - cell 3. 4. input to output voltage error - cell 4.
5 of 10 AN143 application note www.xicor.com lot 2 5. input to output voltage error - cell 1 6. input to output voltage error - cell 2
6 of 10 AN143 application note www.xicor.com 7. input to output voltage error - cell 3 8. input to output voltage error - cell 4
7 of 10 AN143 application note www.xicor.com lot 3 9. input to output voltage error - cell 1. 10. input to output voltage error - cell 2.
8 of 10 AN143 application note www.xicor.com 11. input to output voltage error - cell 3. 12. input to output voltage error - cell 4
9 of 10 AN143 application note www.xicor.com combine all lots 13. input to output voltage error - cell 1. 14. input to output voltage error - cell 2.
10 of 10 AN143 application note www.xicor.com 15. input to output voltage error - cell 3. 16. input to output voltage error - cell 4. xicor, inc., the xicor logo, e2pot, xdcp, xbga, autostore, direct write cell, concurrent read-write, pass, mps, pushpot, block lock, identiprom, e2key, x24c16, secureflash, and serialflash are all trademarks or registered trademarks of xicor, inc. all other brand and product names menti oned herein are used for identi?cation purposes only, and are trademarks or registered trademarks of their respective holders. xicor incor p orated, 1511 bucke y e drive, mil p itas, california 95035-7493
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