Other Parts Discussed in Thread: OP27, OPA827, OPA627
Customer is asking if this device has any warm up time requirement so can meet our accuracy/drift spec? Thanks!
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when looking into the datasheets of OP27, OPA627 and OPA827 I would wait 3...4 minutes after power-on to get full precision of chip. It depends a bit on supply current, supply voltage and load current, or by other words, it depends on the total heat dissipation of chip: The lower the heat dissipation the faster the chip achieves the point where the offset voltage drift becomes marginal.
Thanks for the input.
Customer wants to know if TI ever tested this spec - warm up time to reach specified spec?
If no, it's ok.
Per customer's input, some test instruments manual would put a note saying please wait for 30 mins to warm up before using to avoid accuracy problem. My customer also met this kind of problem - warm up time not enough and fail the test. So wants to check around if any requirement for our ICs.
I am requesting the warm up time from the characterization lab. Since this part is designed 20 years ago, it is possible that we may not have such data. I will post it, if we have it.
The IC's warm up time per performance specification has to be determined empirically. It is not surprising that a piece of precision equipment may require 30-60 minutes to reach a thermal equilibrium. In an IC level, 5-10 minutes may be required. But in a system level, the warm-up may take a lot longer, as you stated above. So you may ask a customer to determine the pass or fail warm up period empirically. Perform a binary search patterns to determine the warm up threshold time. If the tested equipment passes in X mins, you can perform the same test by reducing the warm up time in X/2 mins etc.. Of course, the warm up periods may be affected by variation in building temperature in different seasons, but the warm up time is typically specified in minimum time.
Thanks I already discussed with customer with your good idea, customer can accept it. -)
Customer doesn't have time to find out exact time need for PASS. No mechanical stress during test. On the entire signal path, there is one AD8221 has this data shown below. It doesn't look like the root cause though. Customer is still searching it. Thanks!