Hello,
My customer would like to use the LM7321 as a replacement for the MIC7300YM5 in the circuit below.
1. Is there any problem with using a cap of 1uF or more on the out pin?
2. Could you please provide an application example for using uF cap on the LM7321 out pin?
Thank you.
JH
Hello JH,
Please see the following TI Precision Labs Video on stability and calculating for isolation resistors. As Michael Steffes said, the 10Ohm series resistance helps with stability. If you look at Figure 42 of the datasheet (included below for convenience) you can see that for a cap load of 1000pF, your phase margin is roughly 23 degrees, which is not very stable. With no isolation resistor you would not be able to drive a 1uF load. Adding an isolation resistor helps your stability. The TI Precision Labs Video series explains how to calculate the necessary Riso value for the capacitive load you are trying to drive.
Best,
Jerry
Hi Jh,
it's a bit difficult to perform a proper phase stability anaylsis because TI does not specify the input capacitance of LM7321. Nevertheless, I think that the addition of a small phase lead capacitance would be helpful:
Kai
