TLV62569A: Cout capacitor

Hi David,

Please see comments below as highlighted.

1) Do you see any problem regarding load transient or instability for this configuration? --> Output capacitance outside the Lout and Cout matrix shown in the datasheet might result to low phase margin and/or output voltage oscillation during transient load. I suggest to check the phase margin (= > 40deg.) or its transient response (slva381b).

2) Because the effective Cout is more than 47uF, or is the 22uF-47uF from DS minimal value? --> The Cout in the matrix is the nominal value while the effective capacitance is in the range of +20% to -50%.

3) what is the negative impact of this much capacitance? --> Reduce phase margin

4) if we add a cff will this make a difference? --> It is a case to case basis but it is a worth to try. Check the app note (SLVA289B)

Is it possible and how to simulate this with WEBENCH? --> It is not possible to use WEBENCH for loop stability measurement.

Simplifying Stability Checks_slva381b.pdf

Optimizing Transient Response of Internally Compensated_slva289b.pdf

Best regards,

Excel

Dear Excel,

thank you for the replay. I have couple of more questions.

1a) Because the AC simulation ( bode-plot) is not possible in WEBENCH, is the transient possible?

1b) What is the proper way to set-up the transient simulation for TLV62569A IN WEBENCH to check stability?

1c) How can i add Cff in WEBENCH for TLV62569A?

1d) if non of above is possible, how can i export this to TINA TI? Which simulation ( AC Bode, or transient) is available for TLV62569A in TINA-TI?

2) Which of your devices would your recommend over TLV62569A that is in similar price range?

Best Regards.

Hi David,

Please see response below as highlighted.

1a) Because the AC simulation ( bode-plot) is not possible in WEBENCH, is the transient possible? --> Yes, you can simulate transient in WEBENCH. The transient load parameters can modified as well. See figure below.

1b) What is the proper way to set-up the transient simulation for TLV62569A IN WEBENCH to check stability? --> The necessary transient load parameters can be configured. See figure below.

1c) How can i add Cff in WEBENCH for TLV62569A? --> WEBENCH does not support feedforward capacitor on TLV62569A.

1d) if non of above is possible, how can i export this to TINA TI? Which simulation ( AC Bode, or transient) is available for TLV62569A in TINA-TI? --> I will get back to you on how to convert the WEBENCH model so it will work in TINA-TI platform.

2) Which of your devices would your recommend over TLV62569A that is in similar price range? --> TLV62569A is from the value line product so this is the most cost effective solution.

Best regards,

Excel

Hi David,

I cannot make the pspice model worked in TI-TINA. Do you have Cadence or Simetrix because the model should work?

Best regards,

Excel

Dear Excel,

please can you provide the simulation in Cadence? then i will try it out.

Best Regards,

David.

Dear David,

Sorry for a delayed response, Excel is not feeling well. The pspice model is available on the following link:

http://www.ti.com/product/TLV62569A/toolssoftware

I have also attached the model with this post for your convenience.

Pls let me know if you need additional help.

Thanks and Regards,

Zain Riaz

slvmco2.zip