Dual Schottky in a DPAK — what this part is
The STPS640CB is a dual Schottky rectifier from STMicroelectronics, pairing two 40 V, 3 A diodes in a common-cathode configuration inside a single DPAK (TO-252) surface-mount package. The common-cathode layout means both anodes are independent while the cathode tab is shared — typical for center-tapped secondary rectification or OR-ing diode arrays in low-voltage power supplies.
Forward drop and leakage — the thermal budget drivers
At 3 A forward current the maximum forward voltage is 630 mV. The reverse leakage at 40 V is 100 µA.
STMicroelectronics lists the STPS640CB as obsolete.
Package and reflow — DPAK checklist
The tube shipment means parts are not pre-baked for moisture sensitivity; check the MSL level on the date-code-specific label before reflow if the parts have been stored outside a dry cabinet.