Test board: LM5141QRGEVM
Test condition: VOUT = 5 V, DEMB mode, Frequency = 2.2 MHz, others are default set
VIN = 12 V, IOUT = 1 A (Electronic load)
As the figure shows, I observed abnormal waveform under above test condition. There are wide and narrow pulses at SW node. It looks like sub-harmonic, but actually the duty ratio is below 0.5 (VIN=12V,VOUT=5V). Meanwhile, the switching frequency is only 1 MHz, not 2.2 MHz.
My questions are summarized as follows:
1. How does the wide and narrow pulses at the SW node happen? How to avoid this phenomenon?
2. Why the switching frequency is not 2.2MHz?
