MP24894 + external MOSFET (IRL540NSPBF-VB) blows on power-up in 48V LED driver

[3421384967]

Dear MPS,

MP24894 used as the gate driver in a 48V LED/COB driver and the external MOSFET fails on power-up. Key facts:

• Controller: MP24894 (DR used to drive external N-MOSFET)
• MOSFET: IRL540NSPBF-VB
• VIN = 48 V
• EN = 5V
• Load: COB/LED, Vf ≈ 24 V, target constant current 2 A
• Measured: DR ≈ 6 V; with MOSFET removed SW ≈ 48 V; on power-up MOSFET is destroyed (D–S pins shorted)

Questions to the community:

1. From MP24894’s point of view, what design points most likely cause MOSFET to fail on power-up?
2. If replacing the MOSFET, what device characteristics should I prioritize?

Thank you！

[adhish.FAE]

Hi 3421384967,

Welcome to the MPS forums,

The MOSFET not working in your design will be due to the gate voltage(Vgs) not being proper or it is getting too hot due to layout issues, can you try capture VDs, Vgate (DR oin),Il and SW node waveforms for us to review?

In addition, may I know how many LEDs are you trying to load at the output, OR is this is a LED module with 24V Vf?

Regards,
Adhish

[adhish.FAE]

Hi 3421384967,

After taking a quick look at the schematic it looks like, your switching frequency for the inductor is >600Khz, our datasheet recommends this to be between 100kHz and 600kHz. Also the input capacitor of 4.7uF is less as per our recommended EVB designs.

If you don’t want to worry about selecting the FETs, then we have another part that should work for your application which is MP24881. Its a synchronous buck with two internal FETs and comes in a SOIC-8 package such as shown below:

Regards,
Adhish

[vijaybhong555]

HI Ashish,

We are using the MP24881 for Dual channel dali application.

Vin 58V

Vout 8-54V

Iout 1.05A

Pout 20W max at Vout.

L 150uH

We have below observation,

1. While Dimming Sound comes at 100% no observation but 10 % to 90% noise are present

2. We have get 5 no samples from customer complained in that Vin and Ground Pin of 1 Channel showing short.———> As absolute Vin is 65V and im giving 58V only.