Other Parts Discussed in Thread: OPA2188
Hello,
The bias current (max) value of OPA2188 was increased to +/- 18 nA from +/- 4nA at Revision C.
However, the characteristic of Input Bias Current vs. Temperature in Figure 8 is not changed.
Is this characteristic unchanged?
The customer predicts Bias Current Drift from this characteristic.
Is there a change in bias current drift between Rev B and Rev C?
Best Regards,
Ryuji Asaka
Hello Asaka-san,
We apologize for the delay in responding to your post. We have begun experiencing some delays due to the US Holiday season.
You are correct, the maximum input bias current specification over temperature was updated in the revC datasheet while Figure 8 was not changed. Remember that Figure 8 and all other datasheet figures represent typical device performance unless otherwise noted. Therefore Figure 8 was not updated because the performance of a typical device likely did not change, just the limits on what a "maximum" device may show. I'll do a little research to help provide some guidance on why the maximum specification was increased.
The dc input bias current for this type of device is a combination of the effects of the chopping circuitry and the reverse leakage currents of the input protection cells. The leakage current of the protection cells will double every 10 degrees C which begins to dominate the response at higher temperatures.
