TPS5405: Output voltage drop down when the load current increase

aggil liang

Part Number: TPS5405
Other Parts Discussed in Thread: LM5008

Hi Team

We design a DC/DC module using TPS5405 and find output voltage drop down when the load current increase. we try to change frequency, inductor, and Comp, but there are on improvement.

we also use a wire to connect GND Pin and anode of D11. it is the same result. Would you please give some advise ?

LM5008-TPS5405.pcb

over 5 years ago

0 Shawn Nie over 5 years ago

TI__Genius 10070 points

Hi,

What is the load current?

The layout is not good, the LX is connected to inductor with a very thin wire on the bottom layer, and the vias are too few for the power stage.

Shawn

0 aggil liang over 5 years ago in reply to Shawn Nie

Expert 2660 points

Hi Shawn

The max load current is 0.5A and the Vout is drop down to 4.47V.

Can we use one wire to connect Lx between inductor for testing ?

0 Shawn Nie over 5 years ago in reply to aggil liang

TI__Genius 10070 points

Hi,

You can try it, but it is not a good choice, and also there are vias near the input voltage pin. You'd better to redesign the layout referring to TPS5405 user's guide.

Shawn

0 Jason Wang (BSR-MV) over 5 years ago in reply to aggil liang

TI__Genius 9550 points

Hi,
Device pin 7 GND, should be connected to "clear" GND instead of Diode +; try to connect pin 7 to VIN GND or Vout GND and test (cut off the trace between PIN 7 to Diode+)..

0 aggil liang over 5 years ago in reply to Jason Wang (BSR-MV)

Expert 2660 points

Hi Jason
we will try

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TPS5405: Output voltage drop down when the load current increase