TPS5130: Output oscillating at around 6kHz

TPS5130_DIMENSIONING_3V3.xlsDOC0000723678-B.pdf

Hi,

Can you tell me more information about the issue?

Only channel 3 has the instability issue, right? what's the input voltage and output current?

Best regards,

Edwin,

Hello Edwin,

I added just after my first post some details about the design:

1/ TPS5130_DIMENSIONNING_3V3.xls: This file has been downloaded from TI TPS5130 page. In in are all the details about output characteristics.

2/ First picture: in yellow, you have the +3V3 output when oscillating (not systematic) and in blue, the control of the mos connected to Vin (+5V)

3/ Second picture: Same as picture 1 with a zoom showing that duty cycle on control is always maximal

4/ Our schematic about TPS5130 connexions.

In response to your question, yes, only one channel (n°3) has this kind of behavior. The two others (1 and 2) are not affected and the control seems fine (in not periodically stopped like ch3). So refering to picture on page 9 of datasheet, control interruption seems not linked to OVP or UVP (Fault stop from OVP is common to the 3 channels). Input voltage is +5V and output current is 0.5A max.

Thanks for support!

Hello,

i think the reason is the loop issue. can you test bode plot? if not, can you test load transient and upload the waveform?

You also mention that it's ok when C2 changes to 1950pF. it's suggested to use 2000pF cap for C2.

best regards,

Edwin.

Hello,

I placed 2200pF for C2. I can see on scope that oscillation sometimes starts on output increase but stops systematically.

We are working hard on this development, and the power supply topic is still open and ask researches...

In parallel... I am in holiday for 2 weeks... So could you keep this topic open? We will start again here investigations after 20/08.

Many thanks for your support!