Toshiba Semiconductor and Storage CTS05F40,L3F

Overview

CTS05F40 from Toshiba Electronic Devices & Storage Corporation is a silicon epitaxial Schottky barrier diode optimized for high-speed switching in low-voltage DC-DC converters and power management circuits. It delivers 0.5 A average rectified current, 40 V reverse voltage rating, and 0.40 V typical forward voltage at 100 mA - enabling high-efficiency operation in compact power supplies.

For engineers reviewing the CTS05F40 datasheet, CTS05F40 pinout, CTS05F40 application, or CTS05F40 equivalent, key selection criteria include its low forward voltage drop, sub-2 µA reverse leakage at 40 V, 28 pF junction capacitance, CST2 surface-mount package, and thermal design considerations for Schottky diodes under continuous load.

Technical Context

The CTS05F40 employs a planar Schottky barrier structure on silicon epitaxial substrate to minimize forward conduction loss while maintaining fast recovery characteristics. Its low VF and low IR trade-off is engineered for efficiency-critical 3.3 V/5 V output stages where switching frequency exceeds 1 MHz.

Thermal performance is defined with reference to an FR4 board (25.4 mm × 25.4 mm × 1.6 mm, Cu pad area 645 mm²). Junction temperature must be limited to 150 °C, and reverse leakage increases significantly above 85 °C - requiring derating per Toshiba's Reliability Handbook.

Key Specifications

Pinout & Package

CTS05F40 is housed in the CST2 package (Toshiba designation: 1-1P1S), a miniature surface-mount plastic package weighing 0.7 mg. It features a single-diode configuration with two terminals in a cathode-anode layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RB050M-40 and SS14, the CTS05F40 offers the lowest VF at light load and smallest junction capacitance in the CST2 footprint - making it optimal for space-constrained, high-frequency, low-voltage power conversion where efficiency at partial load matters most.

Availability

CTS05F40 is available at Aetrix Electronics and suitable for DC-DC converters, USB power delivery systems, and industrial sensor modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for CTS05F40 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

Toshiba Electronic Devices & Storage Corporation designs and manufactures discrete semiconductors, power devices, and logic ICs with emphasis on reliability, efficiency, and automotive-grade qualification.

The CTS05F40 belongs to Toshiba's CST2-series Schottky diode family, developed specifically for high-efficiency, low-profile power conversion in consumer and industrial applications where thermal and space constraints dominate.

FAQ

What is the maximum junction temperature for CTS05F40, and how does it affect thermal design?

The CTS05F40 has a maximum junction temperature (Tj) of 150 °C. This rating is validated with a specific FR4 PCB layout (25.4 mm × 25.4 mm × 1.6 mm, 645 mm² Cu pad). Exceeding this temperature accelerates degradation and increases reverse leakage exponentially. For reliable operation, designers must calculate thermal resistance from junction-to-ambient using actual board copper area and airflow, and apply derating per Toshiba's Reliability Handbook - especially above 85 °C ambient. The CTS05F40 datasheet provides no thermal resistance value without this reference layout.

Does CTS05F40 support high-frequency switching above 1 MHz?

Yes, the CTS05F40 supports high-frequency switching above 1 MHz due to its low 28 pF junction capacitance and inherent Schottky zero-recovery behavior. Measured Ct is specified at VR = 0 V and f = 1 MHz, and remains stable up to 5 MHz in typical layouts. However, its 1.8 µA reverse leakage at 40 V increases with temperature - so high-frequency operation at elevated ambient (>70 °C) and full VR requires careful thermal management to avoid thermal runaway. The CTS05F40 is commonly used in 1–3 MHz buck converters where low VF and low Ct outweigh leakage concerns.

What does the marking "7L" indicate on the CTS05F40 package?

The marking "7L" is the official Toshiba date and lot code for the CTS05F40. It appears alongside the part number on the device surface and corresponds to manufacturing batch and week/year information per Toshiba's internal coding system. This marking enables traceability and supports quality investigations. It is not a functional identifier or revision code - the full part number CTS05F40 must always be used for ordering, documentation, and replacement. No electrical or mechanical differences exist between units sharing the same CTS05F40 designation regardless of "7L" marking variation.

Can CTS05F40 replace a standard PN junction diode in an existing design?

CTS05F40 can replace a standard PN diode only if the circuit operates within its 40 V reverse voltage and 0.5 A average current limits - and if reverse leakage tolerance is verified. Unlike PN diodes, the CTS05F40 exhibits higher IR (1.8 µA at 40 V vs. <1 nA for PN), which may cause thermal instability in high-temperature, high-voltage bias conditions. Its lower VF improves efficiency but may alter timing in snubber or clamp circuits. Always revalidate thermal performance, leakage-induced power loss, and transient response before substituting CTS05F40 for a PN diode in production hardware.

Is CTS05F40 RoHS compliant and lead-free?

Yes, the CTS05F40 is RoHS compliant and lead-free, as confirmed by Toshiba's environmental compliance documentation. It meets EU Directive 2011/65/EU (RoHS 2) requirements, including restrictions on lead, mercury, cadmium, hexavalent chromium, PBB, and PBDE. The CST2 package uses matte tin plating on terminal surfaces, and all internal materials are qualified per Toshiba's substance management standards. Full compliance reports and material declarations are available upon request from Toshiba or authorized distributors - essential for medical, industrial, and consumer product certifications involving the CTS05F40.