Hi,
We use LM76002RNPR to make a step-down circuit, Vin=12V, Vout=5.1V, RT pin is floating (fsw=500kHz), but we measured that the switching frequency of SW pin of LM76002 is only about 186kHz, which is not expected 500kHz, and the output current is a sine wave, not the expected constant current! The waveform diagram is shown below!
Iout≈0.36A
Iout≈1.45A
Why is the frequency of SW not set to 500kHz? Why is the output current a sine wave?