Post Go back to editing

LT3743EUFD - SW Pin is burning out

Category: Hardware
Product Number: LT3743EUFD


I'm using the LT3743 on a laser diode driver PCB. The input supply voltage is +36V DC and the driver output voltage is around +27V at up to 10A. I've discovered that on some PCBs the output current can run at 1A but when increasing the output to 2A or higher the driver shuts down. Testing the resistance of the SW pin (pin 24) I measure 4.7 Ohms permanently, suggesting that it's burned out somehow. 

During measurement I can see that the the CBOOST voltage may be approaching > 40V and wondered if this was travelling through the boost capacitor on to the SW pin?

Current regulator sheet from Altium.PDF