Hello,
I've been using this IC to drop a 42V rail down to 12V to power an array of high power LEDs. The load current is no greater than an amp, although this is pretty choppy (switching approx 300-500mA at a time). Switching frequency is approx 640kHz.
Over the past months, I've seen almost 10% of these components have their SW and Vin pins short to GND. Replacing the IC clears the issue, but I worry that it's only a matter of time until it happens again.
There is a 100nF capacitor between the Boot and SW pins (as per the datasheet), but I notice that the voltage across this sometimes violates the absolute maximum value in the datasheet (sometimes spiking to almost 16V for <10ns). What could cause this? Also, where does the 8V abs max value come from? Is this a silicone restriction (FET Vgs max etc), or something else?
I'm *not* seeing a great deal of overshoot on Vin on power-up and, besides this Boot-SW voltage spike, the part seems to be working reasonably well until chip failure.
I notice that there are a few threads of this nature surrounding this part, and wonder if anyone's been able to resolve this issue?
Thanks in advance,
Nick