Part Number: OPA2196
Team,
my customer wants to use OPA2196 in two configurations, but they are not sure if this is best device.
The functions to realize are:
Our datasheet specifies "capacitive load drive capability" of 1nF.
Is this referring to a specific frequency?
What is the limiting factor regarding this parameter?
Other datasheets often show more detailed curves, unfortunately not the OPA2196.
Thanks!
Hello Franziskus,
Too much delay between the amplifier output and the inverting feedback input is a root cause of op amp stability (or oscillation) issues. In the case of capacitive load at the op amp output, the op amp's open-loop output impedance, Ro, interacts with the load capacitance to form a delay causing stability issues.
The OPA2196 datasheet offers two plots of the OPAx197 overshoot versus capacitive load. Figure 20 on page 14, shows the small-signal overshoot of the amplifier vs capacitive load on the inverting configuration (G=-1) and Figure 21 shows the overshoot of the amplifier on the non-inverting configuration (G=1) with different isolation resistors (RISO =0Ω, 25Ω, 50Ω). The % overshoot is an indicator of phase margin or stability. A conservative approach is to design circuits with 45 degrees of phase margin, which typically corresponds to 20% (or less) overshoot.
There are different ways to compensate the amplifier to drive capacitive loads, for example using an isolation resistor RISO.
If you have a specific requirements of the reference drive circuit, and or buffer capacitive load requirements we could offer suggestions.
Also, If you would like to learn the basics of op-amp stability, please refer to the Precision Labs Video Series on Stability (link below).
Thank you,
Best Regards,
Luis
https://training.ti.com/ti-precision-labs-op-amps#section-10
