TPS54239: Load current

Moti Esh

Part Number: TPS54239

The device works well up to 100mA load,the frequency is 600kHz. At load 130mA the voltage drops by 1.3V and the frequency is 300kHz with bizarre waveform on Pin 3, see below. At 200mA load the output voltage pulsating with 0.5V average. We use the exactly recommended circuit, see below. What is the problem?

over 4 years ago

0 Ryan Hu (BSR-MV) over 4 years ago

TI__Expert 4035 points

Hi Moti,

What's your output cap info, like the rate voltage and size? Can you try with one or two more output cap at the output side?

0 Moti Esh over 4 years ago in reply to Ryan Hu (BSR-MV)

Prodigy 60 points

Hi,

Thank you. Their are more two caps, 100u aluminium and 0.1u ceramic. Does it possible brcause fake devices?

BR,

Moti

0 Ryan Hu (BSR-MV) over 4 years ago in reply to Moti Esh

TI__Expert 4035 points

Hi Moti,

From your schematic, I see the 22uF. If you actually used the 100uF aluminium cap, please also add one 10uF or 22uF MLCC cap in parallel with the 100uF aluminium cap to see if any improvement. Also maybe you can check without the 1uH inductor.

If no improvement by doing above, i need check your PCB layout, thanks.

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TPS54239: Load current