We were told the OPA1604 was a drop in replacement for the National LME49740. Upon testing a new build, we are getting considerable overshoot on a comparative circuit we used the OPA1604 on to replace the LME49740. Has anyone experienced a difference when using the replacement chip? Is there a better replacement?
Rick,
The LME49740 is specified with a typical spec of 16% overshoot with a 100pF cap load. The percent overshoot vs cap load curves for the OPA1604 are shown below.
How much capacitive load do you have? Is it possible to damp the overshoot down in your circuit with an Rs resistor as shown below?
The LMP8674MA has a settling time of 1.2us with a cap load of 100pF in a gain of -1.
With the OPA1602 you can tame down the overshoot as well as shown below by adding a capacitor in the feedback path. This may be a quick and easy way to achieve similar overshoot as the other devices.
