WEBENCH® Tools/TPS40170: TPS40170

user4469934

Prodigy 40 points

Part Number: TPS40170

Tool/software: WEBENCH® Design Tools

I fill in the reference board data in TPS40KType III Loop Stability.xls but get a different bode plot

Which data I fill in is wrong?

47uF: 23.5uF degrade@25°C 5V 300Khz ESR:2m ohm

10uF: 4uF degrade25°C 5V 300Khz ESR:5m ohm

Cout:3x23.5uF+2x4uF ESR:0.6m ohm

over 4 years ago

0 user4469934 over 4 years ago

Prodigy 40 points

If this 5V power source as the middle power, the Cout_CER need consider next DC-DC buck `s Cin？

0 Katelyn Wiggenhorn over 4 years ago in reply to user4469934

TI__Genius 11040 points

Hello,

Thank you for your detailed information on the schematic and component selection calculator spread sheet. Would you also be able to share the loop response that you are measuring on your board? This will help us understand if there is a pole/zero which is causing an issue.

Thank you,
Katelyn

0 Katelyn Wiggenhorn over 4 years ago in reply to Katelyn Wiggenhorn

TI__Genius 11040 points

Hello,

I want to follow up with you on this thread. Would you be able to share the loop response that you are measuring on your board? This helps us understand if there a pole/zero which is causing the issue.

Thank you,
Katelyn

0 user4469934 over 4 years ago in reply to Katelyn Wiggenhorn

Prodigy 40 points

Katelyn:

Thanks for you mail

Limited by instrument we can`t get the real bode plot.

Accessories is our schematic

We find Vout oscillating when measure ripple voltage and ripple current by scope. Look like the system is unstable.

But it show normal when use excel tool fill in the data.

So we whant to know how data we should key in to more accurate when use this tool

We get a better ripple voltage (Vripple=50mv)when tune the loopback parameter aimless as follow picture

But is become more worse(Vripple=1V) when in -40°C ambient temperature

Is there any advice to us for our power system

dingtao

0 Robert Blattner over 4 years ago in reply to user4469934

TI__Expert 6165 points

Hello dingtao,

Is it possible to check responce to a load transient? If the converter is untable, the response will show ringing. The easiest way is to connect the output ot a load resistor through a MOSFET and drive the MOSFET with a pulse generator.

Regards, Robert

0 Robert Blattner over 4 years ago in reply to Robert Blattner

TI__Expert 6165 points

Hello dingtao,

My last response was hard to read so I am reposting:

Is it possible to check response to a load transient? If the converter is unstable, the response will show ringing. The easiest way is to connect the output to a load resistor through a MOSFET and drive the MOSFET with a pulse generator. While it is easier to analyze a Bode plot, the response to a load transient contains most of the same information. If possible, monitor output voltage offset or AC coupled so that detail can be seen and load current.

Regards, Robert

0 Katelyn Wiggenhorn over 4 years ago in reply to Robert Blattner

TI__Genius 11040 points

Hello,

As Robert mentioned, is it possible to check the load transient response? This will be the easiest way to measure the stability without a bode plot.

Thank you,
Katelyn

0 Katelyn Wiggenhorn over 4 years ago in reply to Katelyn Wiggenhorn

TI__Genius 11040 points

Hello,

I wan to follow up with you on this e2e thread.

As Robert mentioned, is it possible to check the load transient response? This will be the easiest way to measure the stability without a bode plot.

Thank you,
Katelyn

0 Katelyn Wiggenhorn over 4 years ago in reply to Katelyn Wiggenhorn

TI__Genius 11040 points

Hello,

Due to inactivity, I am going to close this thread. If you have any additional questions, please respond to this post to reopen the thread.

Thank you,
Katelyn

Power management

Power management forum

WEBENCH® Tools/TPS40170: TPS40170