STMicroelectronics STPS640CB

Overview

STPS640CB from STMicroelectronics is a dual common-cathode Schottky rectifier in DPAK package, rated for 40 V reverse voltage and 2 × 3 A average forward current per diode, with typical forward voltage of 0.50 V at 125 °C and 3 A - optimized for high-frequency free-wheeling and polarity protection in SMPS and DC-DC converters.

For engineers reviewing the STPS640CB datasheet, STPS640CB pinout, STPS640CB application, or STPS640CB equivalent, key selection criteria include low conduction loss (P = 0.42×IF(AV) + 0.050×IF²(RMS)), avalanche-rated 90 W peak power, thermal resistance of 5.5 °C/W (junction-to-case per diode), and ECOPACK®2 compliance for industrial-grade reliability.

Technical Context

This dual Schottky rectifier integrates two independent anodes sharing a common cathode terminal, enabling synchronous freewheeling or dual-path rectification in buck/boost topologies. Its low VF and negligible switching losses stem from platinum-silicide Schottky barrier construction and optimized epitaxial layer design.

Thermal coupling between diodes is characterized by Rth(c) = 0.5 °C/W, requiring derating when both diodes conduct simultaneously: ΔTj(diode1) = P₁×5.5 + P₂×0.5. The device operates up to 150 °C junction temperature and supports surge currents up to 75 A (10 ms sinusoidal).

Key Specifications

Pinout & Package

DPAK (TO-252) thermally enhanced surface-mount package with exposed metal tab for direct PCB copper thermal conduction; 3-pin configuration: two anodes (A1, A2) and one common cathode (K).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual Schottky rectifier applications.

Compared with SS54-E3/57T and MBR640FCT, STPS640CB delivers superior power density via DPAK thermal conduction, lower VF at elevated temperature, and integrated dual functionality - making it optimal for space-constrained, high-efficiency SMPS where thermal coupling and layout simplicity matter.

Availability

STPS640CB is available at Aetrix Electronics and suitable for server power supplies, industrial DC-DC converters, telecom rectifier modules, and automotive body control units requiring stable component supply across multi-year production cycles.

Supply support for STPS640CB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.

STPS640CB belongs to ST's Power Schottky Rectifier product line, engineered specifically for high-frequency, high-efficiency power conversion where low VF, fast switching, and avalanche ruggedness are critical in compact form factors.

FAQ

What is the maximum junction temperature and how is thermal derating handled?

The STPS640CB has a maximum junction temperature of 150 °C. Derating follows the condition (dPtot/dTj) < (1/Rth(j-a)) to prevent thermal runaway. When both diodes operate simultaneously, junction temperature rise is calculated as ΔTj(diode1) = P₁×5.5 + P₂×0.5 °C, using per-diode Rth(j-c) and coupling resistance Rth(c) = 0.5 °C/W.

Does STPS640CB support avalanche operation, and under what conditions?

Yes - STPS640CB is fully avalanche-rated with PARM = 90 W at tp = 10 µs and Tj = 125 °C. It is tested and guaranteed for repetitive avalanche events within these limits, eliminating the need for external clamping in most 40 V bus protection applications, including ISO 7637-2 load dump scenarios.

How does the DPAK package improve thermal performance versus TO-220 or SMC?

The DPAK package features an exposed metal tab that enables direct conduction cooling to PCB copper, achieving Rth(j-c) = 5.5 °C/W per diode - significantly lower than TO-220 (≈10–15 °C/W) or SMC (≈8–10 °C/W). This allows higher power density and simplified thermal design without additional heatsinks in many applications.

Can STPS640CB replace two separate Schottky diodes in a design?

Yes - its dual common-cathode configuration replaces two discrete Schottky diodes (e.g., two 3 A/40 V devices), reducing component count, PCB area, and parasitic inductance. Pin-compatible replacement requires verifying anode separation and ensuring shared cathode routing matches existing layout constraints.