I am using the STPS5L60U in a low voltage landscape driver design. Input is 9-15Vac. Circuit is a buck-boost. Driver chip is a TI LM3429, driving an external FET. Switching frequency is only 145kHz. COB load is 20V and 750mA. I use 4 of these diodes to make the bridge, and they have always worked perfect here. Then a 5th location at the output diode. Recently, I have had problems with the STPS5L60U as the output diode. At elevated temperatures for HALT/ALT (60-65C), the diode is causing the driver chip and/or external FET to blow. At these elevated temperatures, the diode tab is only 100C with a junction rating of 150C. I am no where near maximum. If I put an equivalent PANJIT part in, I can run at that temperature, in addition to another 20-25C. If I put 3A/60V schottky from say Diodes Inc., I run at the elevated temperature, in addition to another 20-25C. It seems the performance of the STPS5L60U has degraded over time. It cannot be used in high frequency switching applications. It seems like maybe a leakage current issue when it is supposed to be blocking. I know 100% the cause of my failures in the ST part. Other manufacturers parts don't blow my driver chip or FET. Are there known quality issues that have crept up in the last year or two? Any idea why your diode would cause the driver chip and/or FET to blow?
