Tool/software:
Hi,
We use the LM3409HV for the LED Drivers, and now, we have below issue:
1. The circuit spec: The input voltage of LM3409HV is 40VDC, LED voltage is 32V, LED current is 3A, the inductance is 10uH;
Our issue: It is Internal thermal shutdown after LM3409HV work about 5mins when we set No FET PWM Dimming mode(FET Shunt) ;
2. The waveform refer to below:
1) The current waveform for the FET shunt;
2) The turn on time waveform:
3) The turn off time waveform:
4) The Iout waveform, the Imax=3.5A, the average current value=3A;
5) The PWM dimming Frequency is 40KHz, Duty cycle is 30%;
6) The pink one is the G-pole voltage waveform of FET Shun , and the high-level driving voltage is 12V:
7) The waveform of the current when the FET shnut turn on:
8) The detail waveform, the current has the ringing phenomenon:
9) Please advise if we can reduce the charging time, we try to increase the input voltage but It doesn't have much effect, and we update to larger inductance, but the charging time is Longer:
10) Plesae kindky review the schematic and MOSFET datasheet, and then advise how to solve this issue, thanks.
