This thread has been locked.
If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.
I have a circuit that uses the LMC662 and in development, which used LDC HKAN parts, everything works as expected. However, when we went to production which used LDC 8CX7 parts, the performance of the circuit is very different. I've been able to simulate more of the observables and believe it to be a difference in offset current between the two lots of parts. Does TI have any test data captured on these two lots of parts that could be provided to do a side by side comparison of these parasitic parameters to see if that is what's causing my issue?
Tom
Tom,
In addition to the symbolization on the package, I also need the full part number.
Through simulation, I believe it to be about 0.2pA versus the advertised typical of 2fA where our prototypes were running. It also various sightly in time.
Tom,
I got a response back; 'HKAN' is not a valid part marking.
If the issue is a 0.2pA offset, could that be due to the circuit board or contaminates on it?
The data sheet has a section for "PRINTED-CIRCUIT-BOARD LAYOUT FOR HIGH-IMPEDANCE WORK"; were these practices followed faithfully?
Also the lower the current the longer the time to measure it, therefore the test program likely only tests long enough to a verify a resolution of 100’s of femto-amps. There would be no way to know the difference between 2fA and 20fA
Having replaced the HKAN part with an M6AB from a previous known good working set of assemblies, the new assembly still exhibits the strange behavior seen with the HKAN part. So I'm comfortable eliminating this as the root cause and consider this issue closed from TI's point of view.
Thank you.
One follow-up question, please confirm that the HKAN marking is or is not a TI marking. If it's not, I need to trace this part back to see where it came from. Not necessarily related to this issue directly, but I want to make sure I know where these parts are coming from.
Thanks.
Tom,
TI uses the first symbol (0-9) to reflect year's last digit and second symbol as month (1-C). Prior to National Semiconductor acquisition, the symbol format was likely different. Therefore the 'HKAN' device predates November 2012 (oldest record in database).