Hi there,
I have an issue with a boost circuit based in Lm5122. The circuit is composed by 4 sub circuits, each of one has one LM5122 and their respective componets. Each of one of the circuits has the next features:
Vin:12 V, Vout :16 V.
At the output of each cannel, I have a led string where I applied 16V. At that voltaje the leds are working at 2 A each cannel/string, pulsing this at 1 ms 25 Hz.
I have one issue with the noise produced the output channels of the circuit. FIrst, when ther is no led string connected, the pulse signal an the output voltaje looks the next way (Yellow line is the pulsed line, blue line is the Vout, after inductor and MOSFET, terminals ground and Vrfbt) :
But when I connect the load (the led string) there is a very big noise at the signals:
I guess there is some kind of return noise or maybe some capacitance or inductance that apears once the load is connected, probably because the inductor and mosfet in SW, HO and LO. But I am unable to find why is happening this effect.
It would be very useful if someone could give me some clues about what could I test to avoid this effect
best regards
