TPS60400-Q1: Generating the correct output voltage

Hi Paul,

Thanks for your question.

Do you see any switching on the flying capacitor? Please send an oscilloscope screenshot of VIN, VOUT, CFLY+, CFLY-.

What is the expected output current at the output of the converter?

Thanks,

Stefano

Hello Stefano, 

Please find below the oscilloscope screenshot: 

With Yellow Input, green output, blue CFLY-, and magenta Cfly+

Expected output current is far below 60mA, it is only to drive 2 mosfet gates and a passive circuit, so it should not be an issue to use this charge pump. 

Regards, 

P-A Burdet

Hi Paul,

Thanks for the data.

From the screenshot it seems that the output voltage is less than 2V.

From the schematic it seems that the nominal voltage is 3V. Could you try to increase VIN and check if the device is correctly switching?

I would also advise to zoom in on the VIN ramp, in order to see whether the device is switching at the beginning and if anything strange happens when it stops.

Let me know if I am missing something.

Thanks,

Stefano

Hello Stefano, 

I cannot reproduce it, output is now 0V, and there is no difference anymore whether Vin=3V or Vin = 0 V
I will try to replace it and make measurements again, I will sync up with you when done.

Regards, 
P-A Burdet

Hi Paul,

Ok, I will wait for your feedback.

Thanks,

Stefano