Toshiba Semiconductor and Storage CMS20I40A(TE12L,QM

Overview

CMS20I40A from Toshiba is a Schottky barrier diode optimized for secondary rectification and reverse-current protection in compact DC-DC converters and mobile power circuits. It delivers V_RRM = 40 V, I_F(AV) = 2 A, V_FM ≤ 0.52 V at 2 A, R_th(j-a) = 60 °C/W (on ceramic board), and uses the ultra-thin 3-4E1S (M-FLAT™) package.

For engineers reviewing the CMS20I40A datasheet, CMS20I40A pinout, CMS20I40A application, or CMS20I40A equivalent, key selection criteria include forward voltage drop under 2 A load, thermal resistance in high-density layouts, junction-to-lead thermal path, repetitive peak reverse voltage margin, and suitability for low-profile mobile and portable power designs.

Technical Context

The CMS20I40A employs a planar Schottky junction structure with low-barrier metal-semiconductor contact to achieve fast switching (no minority-carrier storage) and minimal forward conduction loss. Its 40 V V_RRM rating targets 5–12 V output rails in synchronous buck converters where reverse recovery is irrelevant but leakage and thermal stability are critical.

Designed for surface-mount assembly on thermally constrained PCBs, it specifies two thermal resistance values: 60 °C/W (junction-to-ambient, ceramic board) and 135 °C/W (junction-to-ambient, glass-epoxy board), with a dedicated 16 °C/W junction-to-lead value confirming direct cathode lead heat sinking capability.

Key Specifications

Pinout & Package

Package: 3-4E1S (Toshiba M-FLAT™), 2-pin surface-mount, 0.023 g typical weight, 1.0 mm max height, designed for high-density automated placement and reflow soldering.

Key Features

Applications

Equivalent & Alternatives

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

Compared with RB055LAM-40 and SS24, the CMS20I40A offers optimal balance of low-profile packaging, verified 2 A capability, and 0.52 V V_FM performance-making it preferred for new space-constrained, thermally sensitive mobile and portable designs where M-FLAT™ mounting is feasible.

Availability

CMS20I40A is available at Aetrix Electronics and suitable for secondary rectification in switching regulators, reverse-current protection in mobile devices, and battery-isolation circuits requiring stable component supply, long-term lifecycle support, and RoHS-compliant sourcing.

Supply support for CMS20I40A 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 energy efficiency, miniaturization, and reliability for consumer, industrial, and automotive markets.

The CMS20I40A belongs to Toshiba's M-FLAT™ Schottky diode product line, engineered specifically for high-density power conversion and protection in portable electronics where thinness, low forward voltage, and controlled thermal resistance are essential.

FAQ

What is the maximum junction temperature rating for the CMS20I40A?

The CMS20I40A has an absolute maximum junction temperature (T_j) of 150 °C. However, Toshiba recommends limiting steady-state operation to T_j ≤ 120 °C to ensure long-term reliability. This derating guideline applies to the CMS20I40A in all standard mounting configurations and must be validated using the Ta(max)-I_F(AV) curve from the official CMS20I40A datasheet.

Does the CMS20I40A have a specified junction-to-case thermal resistance?

No-the CMS20I40A datasheet does not specify R_th(j-c). Instead, it provides R_th(j-a) = 60 °C/W (on ceramic board) and R_th(j-ℓ) = 16 °C/W (junction-to-lead). The latter confirms that the cathode lead serves as the primary thermal conduction path, and thermal design should focus on optimizing the cathode land pattern per the CMS20I40A land pattern dimensions.

Is the CMS20I40A suitable for use in USB Type-C power delivery applications?

Yes-the CMS20I40A is suitable for USB Type-C power delivery applications requiring reverse-current blocking on VBUS lines. With V_RRM = 40 V and I_F(AV) = 2 A, it supports up to 20 W (5 V/4 A or 9 V/2.2 A) configurations. Its 0.52 V V_FM at 2 A ensures minimal voltage drop, preserving compliance with USB PD voltage regulation requirements across the CMS20I40A's operational range.

What marking code appears on the CMS20I40A package?

The CMS20I40A is marked with "SS" on its top surface, per the official Toshiba marking specification. This 2-character code identifies the device as the CMS20I40A within Toshiba's M-FLAT™ Schottky diode family and is used for traceability and visual inspection during assembly. The full part number "CMS20I40A" also appears in the datasheet marking diagram (Fig. 7.1).

How does the CMS20I40A's thermal resistance compare between ceramic and FR-4 PCBs?

The CMS20I40A exhibits R_th(j-a) = 60 °C/W on a 50 mm × 50 mm ceramic board versus 135 °C/W on an identically sized glass-epoxy (FR-4) board-more than double the thermal resistance. This difference arises from FR-4's lower thermal conductivity and highlights the importance of using the CMS20I40A's dedicated cathode land (R_th(j-ℓ) = 16 °C/W) for reliable thermal management in production designs.