LM5118: problem with HO signal

jesus britoloaiza

Prodigy 60 points

Part Number: LM5118

Hello good morning
I have a noise problem with the HO pin switching signal.
The signal looks like this:

VIN = 24VDC.

VOUT = 12VDC.

switching frequency = 100 KHZ.

I don't have load for the output.

This is my circuit, I got it from webench power designer

thank you very much in advance, I would be very pleased if you could help me.

over 2 years ago

0 Stefan Schauer over 2 years ago

TI__Guru 53711 points

Hi Jesus,

thank you for using the E2E forum.

can you please confirm that the scope plot shown above is from the HO signal and not the HS.

Best regards,

Stefan

0 jesus britoloaiza over 2 years ago in reply to Stefan Schauer

Prodigy 60 points

yes, it is the HO signal, but when i add the load the signal is clean and the pwm looks like it should according to the datasheet. is this normal?

when I have it in my minimum input range and I have the load added, if I try to turn it on the regulator does not start, but if I do a little delay to wait for the regulator to turn on without the load, the regulator does work.
How can I get the regulator to start at my minimum input voltage with the added load, what do I need to modify?