What type of non-volatile memory hast the AD5270? What is its retention time?

Question What type of non-volatile memory hast the AD5270? What is its retention time (time during which the NVM data retains its integrity over time without rewriting another/same value)? Answer The AD5270 uses 50-times programmable memory. A charge pump is used to permanently blow the fuses in memory. There should be no need to re-write the value but allow 350ms for the initial write to the memory. Memory -> array of fuses. Retention -> Forever and ever Endurance -> 50-times

AD527x, how to measure the resistance value of digipot

Question I used SDF to plug in EVAL-AD527XSDZ and power the system by one USB port of the laptop, then using multimeter to test the resistance and compared with the target value shown in the software. 1) If using Agilent 34401A digital multimeter, I got several different results a) When A is connected to 3.3V, “+”of 34401A is connected to A and “-“ is connected to “W”, the resistance from 34401A is correct. b) When A is connected to 3.3V, “-”of 34401A is connected to A and “+“ is connected to “W”, the resistance from 34401A is wrong in some cases. c) When A and W are floating, the results seem correct, which are independent of the connection between 34401A and resistor terminals. d) When A is connected to AGND, “-“ of 34401A is connected to A and “+” is connected to “W”, the results are correct. 2) If using handhold multimeter, the results are always correct, which are independent of the correction between handhold multimeter and resistor terminals. From the above phenomenons, I guess the reason of the wrong results may be the voltage of terminal A or W is above 3.3V. In the datasheet, the voltage of terminal A and W should be between VSS and VDD.But, why the results are always correct when using handhold multimeter? Answer The internal multimeter has a current source, reference to LO input. Depending on the impedance range, this current source forces more or less current. As you pointed before the voltage across the terminals cannot exceed 3.3 +0.3V, in your case. In your first configuration 1a, Agilent force current from A to W, the measurements in this case are correct bc your current source reference is floating. In your second configuration 1b, LO terminal is connected to 3V3 and indirectly you grounded your current reference, using the LDO. Consequently, the voltage generated in the other extreme of the resistor, W, can exceed the maximum allowable voltage, 3.6V and the internal diodes will clamp this voltage. In your third and fourth configurations, you are not exceeding the maximum allowable voltage so no error should be measured. Answering your second question, if the current used by the multimeter is small, the voltage generated by the resistor should not exceed 0.3V.This is the case of a handhold DMM. In general I’d recommend measure the resistance without any connection to the circuit, mainly bc the impedance that you are measuring could be wrong as the DMM always measure the lower impedance.