WEBENCH® Tools/TPS54231: Non stable working (Return to Eco-Mode)

Vladimir Kushner

Part Number: TPS54231

Tool/software: WEBENCH® Design Tools

Hello, everyone! I got this the next problem: during to working DC/DC converter it has intering in Eco-Mode periodically. What the main reason?

over 4 years ago

0 Shawn Nie over 4 years ago

TI__Genius 10070 points

Hi,

Could you please share the waveform and work conditions?

Shawn

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

Here is the output voltage oscillogram, it see that IC skip impulses.

I have floating load, a working current can change from <=100mA to 1A in time.

0 Shawn Nie over 4 years ago in reply to Vladimir Kushner

TI__Genius 10070 points

Hi,

The output voltage ripple is very large, right? It is not very clear.

Please also share the schematic and layout, let's check if there is any issue.

Shawn

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

Hi, Shawn! Yes, right, Eco-Mode IC. Below I put my design. Vin_1 - 5V.

0 Shawn Nie over 4 years ago in reply to Vladimir Kushner

TI__Genius 10070 points

Hi,

The output capacitor is electrolytic capacitor, right? How is the ESR? Large ESR may lead to large output ripple.

Shawn

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

No, ceramic 1206. I don`t know how about ESR, X7R ceramic probably.

I used We bench on-line program, it gave other result are:

Was accepted at 5V input and I load max=1A

0 Shawn Nie over 4 years ago in reply to Vladimir Kushner

TI__Genius 10070 points

Hi,

This device can't support 5V-3.3V, Boot UVLO would be triggered. Below app note is for your reference to solve this issue.

https://www.ti.com/lit/an/slua928a/slua928a.pdf

Shawn

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

I tryed (1) "Diode tied from input to boot" and (2) "Diode tied from output to boot" solutions, but it isn`t lead to positiv result.

Besides, I applied dummy load, chip-resistor on 120 Ohm in parallel to output chain; and increase input capasistance till 60uF for eliminate input voltage ripple.

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

I`ve measured ESR output capasitor is 0,98 Ohm at 100 Hz

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

Here is a fragment of topology:

0 Shawn Nie over 4 years ago in reply to Vladimir Kushner

TI__Genius 10070 points

Hi,

It is normal that the output ripple is large at light load, what is the value of the output ripple on your board?

And it would be better to measure the SW waveform, so that we can know how it works.

In addition, have you tried to increase the input voltage? How is it when vin is higher, such as 12V?

Shawn

0 Vladimir Kushner over 4 years ago in reply to Shawn Nie

Intellectual 280 points

I haven`t tried to increase the input voltage, as I can`t to apply this voltage to my electronic device. It must working from 5V on the input strictly.

For expirement I can do it.