TPS54561: Internal Slope Compensation and Excel Calculator?

Hi

1. I don't have the slope compensation value , it is internally and base on datasheet, it won't affect the loop a lot, cause it is double pole at 0.5fsw.

2. for unlocked version, I check the excel on the web, we don't lock it by password, you can directly unlocked it.

Thanks

Hello Daniel,

I appreciate the fast response but these were unhelpful and inaccurate responses.

1. The inductor pole is not a double pole as you state. It is a single pole and its location (in radians) is equal to Km*Ri/L where Km = 1/((0.5-D)*Ri*T/L + Vslope/Vin) The value of the slope compensation is part of the equation and I have seen many cases where this is much lower than 1/2 the switching frequency.

Please consult the designer of this part to find out the value of internal slope compensation and how it is generated?

Please find out who created this spreadsheet?

At first look it appears the reason they can ignore the slope compensation value in the data sheet when giving the compensation equations is because the geometric-mean equations used give a starting crossover frequency much lower than it needs to be. That said, it does appear they are factoring the slope compensation and inductor pole on the 'Small Signal' worksheet but it is not obvious how/where.

2. As your answer gave no specific directions I had to work through this myself. True, the data sheet is not locked by password as you state, but this means it cannot be unlocked as you say it can be. It turns out it is not locked but 'protected' under the Format menu. Even then, the plot values don't show up in columns G through AA because the text color has been set to white. You need to change the text color to black to make them visible.

Respectfully, Kurt

HI Kurt:

thank you for your info.

1. for the inductor pole is single or double, from I understand, both is OK, cause it is deduce from internal current loop with sample hold transfer function. if you simplified the ZOH with first order, then the transfer function will be the single pole system as your described . if you make it as second order, then it will appeared like a double pole system , when your slope compensation is not enough, then it will have a high Q. Q=(2/Pi)*1/(1-2D+2D*ma/m2), ma is slope and m2 is the inductor current slew rate at 1-D. but I think both can describe the loop system well. 

2. in the excel, the Column G and AA is not pretected, only the text is use white color , if you change to red color, it will appeared.  I unhide the sheet and make them visible, pls let me know whether it is your want to see.

Copy of TPS54360-361FAMILY_CALC_TOOL_REVE.xls

for the slope rate and there is a Se in Small Signal sheet, l line 31, from Fm formula, I think it present the slope value . 

Thanks

"I think" is not an engineering answer and is not helpful.

1) Please find out how slope compensation is implemented and what its value is - I need this for my Matlab calculations. Knowing the actual inductor pole frequency is important when trying to maximize the crossover frequency.

2) I told you in my reply about the protection and the need to change the text color so I am not sure why you are telling me? Please find out who the original author of the spreadsheet is.

Respectfully, Kurt

HI Kurt:

1. Slope compensation is in internal checking, it is old product , original designer is not in our team, pls wait for the answer

2. the original author is not in our group, I don't know who generate this files, I can help check, but I am not sure whether he is in TI.

Thanks

Hi Kurt:

1. Slope is 1A/V which is indicated in the excel  

2 there is no password.

Sorry for the delayed response; I was out of the office for two weeks.

1. Units of A/V are not directly usable unless you provide additional information. Volts of what? Slope compensation is usually in terms of a slope (Volts/time or Amps/time) - please clarify.

2. In my second post above I established the fact that the spreadsheet was not locked by a password and that the text color needed to be changed to become visible. I'm not certain why you are now telling me this again. The task for number two was to determine a) who the original author was and by extension b) who owns it now?

Respectfully, Kurt