Tool/software: WEBENCH® Design Tools
Hallo,
I've designed through the WEBENCH Tool, a DC-DC step-up circuit based on the LM3478 IC (see first image below).
Main requirements was: Vin=+5v Vou=+17v, 600mA max
I've tested the solution and it worked well but, I've discovered that, it introduced glitches/noise on the rest of the circuit board.
Practically, what I've seen is that, during the LM3478 "DR - pin6" output PWM transitions, glitches are present on this signal (second picture below, yellow trace + red circles),and they
are transmitted on some signals of the rest of the circuit too (second picture below, green trace). That glitches affected the correct functiong of the global circuit board.
Their frequency was around 150Mhz (see third picture below).
I've tried to increase the C5 180uF output capacitor and tried to add a filter (R=10ohm + C=1uFcap), on the Vin LM3478 input but, glitches still remained.
Please consider that, the +5v input signal came from an USB-C UL certified power supply so, clean and stable.
There is a method to avoid this problem and remove that glitches from the "DR pin6" PWM signal?
Thanks in advance for the suggestions.
Alex
