Low-voltage Schottky pair for high-current rectification
The STPS40L15CT is a dual Schottky rectifier from STMicroelectronics, configured as a common-cathode pair in a TO-220 through-hole package. The 15 V reverse voltage rating (Vr max) limits this part to low-voltage rails — think 12 V or lower outputs in switch-mode power supplies, OR-ing diodes in redundant power systems, or secondary-side rectification in telecom bricks. The fast recovery characteristic (≤ 500 ns at > 200 mA) is typical for Schottky diodes and supports switching frequencies into the tens of kilohertz without significant reverse-recovery losses.
15 V Vr, 20 A per diode — where the ratings matter
The 15 V reverse voltage is the hard ceiling — never apply more than 15 V reverse bias, even transiently. In a 12 V rail, that leaves only 3 V of headroom, so any ringing or overshoot on the secondary side risks avalanche. For a 5 V output, the margin is comfortable. The 410 mV Vf at 19 A means conduction losses are roughly 7.8 W per diode at full current — thermal management is the limiting factor, not the silicon. Reverse leakage is 6 mA at 15 V — typical for a low-Vf Schottky. That leakage doubles with temperature, so at high junction temps the leakage power adds to the thermal budget.
The closest functional alternative within the same family is the STPS40L15CG, which differs in package (D²PAK vs TO-220).