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TPS62143 output voltage drops down

Other Parts Discussed in Thread: TPS62143

Hi Community.


I have soldered schematic with the TPS62143 as Voltageregulator. I selected the components according to the WebBench Design Report. The partnumbers are not the same because my distributor did not sell them but the parameters are the required one. I used this coil.

The input voltage range is 6V - 15V, output voltage = 5V and my schematic needs about 200mA.

The Problem is, that the output voltage drops down to about 3,4V if the input voltage exceeds about 10V.

At first, I thought that the Switcher is damaged and changed it. But the second one has the same behavior.

I have also a seconds (another board) with this switcher and nearly the same desgin with the same parts and this one works very fine.

Can anyone help me to find out why the voltage drop happens?

Here is the design:

  • I have found the solution by myself. The C on the output was for 6 V and not for 10 as assumed. I changed the capacitor and soldered a wire from the Caps Ground to the Switchers Ground to shortend the path. Now all works fine.

  • I have exactly the same problem. The regulator works until Vin = 7.6. After that, Vout decreases until at Vin = 12V, Vout is about 3.8V.

    My design is a Vin 12v, Vout 5V regulator

    The situation is worst under load.

     I don't believe that the capacitor voltage rating would have anything with this problem but I went ahead an replaced the output cap with one with a 25V rating to no avail.

    I think the regulator is unstable and tends to oscillate when Vin > 7.5V. Possible cause can be layout (in my case) I am using a two layer pcb. I have to say that my layout is very similar to yours, though....