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TLV62585: Compensation design for TLV62585

Leo Wu28
Prodigy 210 points
Part Number: TLV62585

Hi Ti,

I am using TLV62585 and encountering a problem with compensation design, below is my design component:

Input 3.3v, 10uf Cap + 100nf

Output 0.85V, 10uf +22uf +100nf , No Cff

Divide resister : R1 200K , R2 475K

I got a bed PM(26 degree)/GM(-4.5dB) result with above components.

There are some questions :

1. What is the compensation type of TLV62585 internal compensation circuit ? TYPE II or TYPE III?

2. Do you have any PM/GM test result about TLV62585 EVM?

3. I change the divide resister to 37K and 91K, PM will increase to 5x degree, GM still fail (-5.xdb), I don't know why? is Divide resister a Zero or Pole?

Thank you!

  • 0
    TI__Expert 5425 points
    Hi Leo,

    the device is designed to operate stable with enough gain and phase margin if you use the recommended application circuit configuration. The modifications you did at the FB divider already confirmed that. Using 475k for R2 instead of the recommended 100k makes the circuit much more sensitive to parasitics in the design and in the measurement setup.
    Compensation circuits for internally compensated devices are usually more complex than simple type II or type III circuits. Please understand that we can not discuss any device internals in this forum.

    Regards,
    Juergen