Tool/software:
Hi Team,
I see below comment in datasheet.
And my question is that how to select the appropriate output cap to get proper system stability? As I know, LDO is one pole architecture. Does zero generating by output cap ESR improve the system stability?
Regards,
Roy
Hey Roy,
Especially for some of our older devices, minimum ESR was essential to maintaining LDO stability. Our newer devices have a more robust compensation network, that allows them to be compensated with low ESR capacitors, like ceramics.
The internal ESR forms a zero with the output capacitor whose frequency can be calculated from: ZESR = 1 / (2 X π X ESR X COUT).
The zero increases the phase margin at the calculated frequency to make the device more stable across frequency.
You would know what type of compensation network you need based on a gain and phase margin analysis of your system and the system requirements.
This article may be helpful in aiding your understanding: AN-1482 LDO Regulator Stability Using Ceramic Output Capacitors (Rev. A) (ti.com)
