XDPL8219 Power Supply - Op Amp Alternative for Feedback Side

[omerfaruk]

Hi,

Regarding XDPL8219 OpAmp component selection

Greetings, we're developing a power supply based on XDPL8219 IC's reference design. We're not even close to advanced electronic skill level so we have a question about the selection to OpAmp IC.

In reference design, there is used [TSM103WAIDT] but we're trying to find alternatives for it, so we have a few questions;

Ref Design Document: https://www.infineon.com/dgdl/Infineon-Engineering_report_REF-XDPL8219-U40W-ApplicationNotes-v01_01-...

1) Is the SR - Slew Rate very critical here? What is an optimal range of the slew rate for OpAmp for XDPL8219
2) Same as above but, GBP - Gain Bandwidth Product.

TSM103WAIDT
SR: 0.4 V/us
GBP: 900 kHz

So,  For example, We can select 1000 kHz or 0.35 V/us?

Is there any +- limit or percent for both of these values of the Op Amp?

Thank you very much

Best Regards

[Kanahaiya_K · Accepted solution]

Hi
Thank you for posting on the Infineon Community.

Slew rate is a critical parameter here because it depends on the frequency and peak value of the output voltage.

The slew rate of the opamp is limited due to the stability. The output of the high-speed amplifier will go beyond the final value and oscillate around the final value. So, the amount of overshoot and ringing value will indicate the phase margin. As the overshoot increases, phase margin will decrease and it affects the stability. The Gain bandwidth product is defined as the product of the open loop voltage gain and the frequency .
 Can you let us know why do you want to change the slew rate and gain bandwidth? what voltage do you expect at the output terminal of opamp and what is the operating frequency?

For more details related to the design, please refer to the attached documents
https://www.infineon.com/dgdl/Infineon-Design_guide_lighting_ICs_XDPL8219_XDP_digital_power-Applicat... 

Best Regards
Kanahaiya