TPS61161 Loop Compensation Cap and Crossover Freq

Hi Bell

You can use the attached application report from the TPS61170 for the TPS61161.  When driving LED you can use 20 per LED for ROUT.

Let me know if you have any questions.

Best regards,

Randy

slva319c.pdf

Hi Randy,

From the datasheet,
What is the Error amplifier crossover frequency 500kHz? The 500kHz is the crossover Freq of the EA?

With the test conditions of 5pF connected to COMP and Rea=6M ohm. crossover fre=500k, the equation: G*(R*1/SC)/(R+1/SC)=1.
We can deduce the parasitic cap = 100pF. Is this correct?

Thank you

Bell

Hi Bell

I'm not sure about your simplified equation or what exactly you need to understand.

I'm attaching an app note from the TPS61170 which should help you with the TPS61161 since they have same boost architecture.

slva319c_tps61170_boost_comp.pdf

Randy

Hi Randy,

Thank you and I've read the application note you attached. 

My question is simple:

Could you explain more about the crossover frequency 500kHz?

1. 500 kHz Is the crossover frequency of Error amplifier  ?

2. Where does the 500 KHz come from? Is there a formula to calculate this?

Thank you!

Bell

Hi Randy,

Any updates on this?


Thank you!
Bell

Hi Bell,

There are not any formulas to calculate the 500 kHz. This value is considered a maximum value but is not used in normal operation.

Randy