Hello,
I'm trying to develop led power supplier using LM3429 in boost topology using LM3429 Boost Evaluation Board.
My conditions:
Input Voltage: 17V - 30V
Output Voltage: 36 V
Output current 230 mA
Switching Frequency 850 kHz
Inductor Value 220 uH
Transistor Q1: IRFR4105ZPBF
So my problems are:
1. I 've got the problem when I'm increasing Input Voltage to about 28 V. Then I can hear the Inductor and the GATE pin of LM3429 works unstable. Duty cycle's changing from 10 to 30%. What can cause this problem?
2. When LM3429 turns on the Q1 transistor, there is quite big ringing problem. Voltage on GATE pin of LM3429 can be above 15 V. The riniging frequency is about 100 MHz. I suppose it cause EMC emission problem. Is it some way to minimise it?
Thank you in advance,
Cris