NewsROHM’s Compact PMDE Package Diodes: Contributing to Application Miniaturization

ROHM’s Compact PMDE Package Diodes: Contributing to Application Miniaturization

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ROHM introduced 14 brand new designs to the PMDE packaging (2.5mm in size x 1.3mm) range – which meets the demands for smaller switches and protection circuits. (RBxx8 Series, RFN Series, VS Series)

Diodes are utilized for rectification, protection , and switching circuits in a broad spectrum of applications, including industrial, automotive and consumer sectors. In addition, there is an increasing need to decrease dimensions of the device to limit space for mounting. However it is essential to have higher performance to lower the amount of power consumed.

But, as you reduce the dimensions of the package, the surface that the electrodes on both sides as well as mold is also reduced and results in less heat dissipation. To address this problem ROHM’s PMDE package boosts heat dissipation efficiency via expanding the electrode on backside while also optimizing the way heat is dissipated.

This provides the identical electrical characteristics of traditional packages, but with smaller sizes of packages.

ROHM’s exclusive compact PMDE package comes with an equivalent land pattern to that of the traditional SOD-323 model. The review of the backside electrode and the heat dissipation route made it possible for ROHM to attain the same electrical properties (i.e. current and resist voltage) like the SOD-123FL standard packaging (3.5mm in size x 1.6mm) with smaller size which contributes to the board’s miniaturization as it decreases the size of the mounting surface by around 42 percent. In addition, the mechanical strength is approximately 1.4 times greater than the SOD-123FL package, decreasing the chance of solder cracking when strain occurs on the boards, providing more reliability in mounting.

The PMDE line-up of PMDE packages includes eight models from the RBxx8 series of Schottky barrier diodes (SBDs) and 2 models from the RFN series of fast recovery diodes (FRDs) and two models from the VS series of transient voltage suppressors (TVSs). A wide range of circuit applications are possible by using compact diodes.

Moving forward, ROHM will strive to enhance the performance of its semiconductors that range from low to high-voltage devices while improving its distinct line of products to further reduce power consumption and improve packaging miniaturization.

Key Features of the PMDE Package

  1. Significantly improved heat dissipation achieves 42% smaller mounting area.

Generallyspeaking, semiconductor components transfer heat that is generated into the atmosphere and through their substrate. When reducing the package dimensions, the area on the electrode’s back and mold is also reduced and results in less heat dissipation.

This PMDE package, in order to address this issue, expands the area of the back electrode in order to improve the heat dissipation route between the frame and the substrate. This results in significantly better heat dissipation efficiency, while with the same electrical characteristics similar to the standard SOD-123FL packaging (3.5mm by 1.6mm) but less 2.5mm x 1.3mm dimension. This is equivalent to 42% smaller area for mounting which makes it perfect in automotive environments where greater quality components are required.

  1. Ensures higher reliability compared to conventional packages

The PMDE package can achieve an effective mounted strength of 34.8N which is approximately 1.4 times more than the SOD-123FL product, by expanding the size of the metal component that allows for a greater backside electrode. This lowers the possibility of cracking solder when stress applies to the boards, which contributes to better durability. The ability to withstand high surge currents (I FSM) can also be achieved through the use of an unwired structure in which the chip is interspersed between the frames. The resulting high surge resist ability (I FSM) offers superior resistance to damage caused by sudden surges of current that can occur at the time of vehicle start, or during malfunctioning devices.

PMDE Package Products

The PMDE package provides the same electrical properties like the standard SOD-123FL package but with a smaller size that provides better heat dissipation and mounting stability. In addition, all automotive-compatible part numbers are qualified under the AEC-Q101 standard for automotive reliability. The new ranges of PMDE packages are as follows. (SBDs: RBR series only In mass production starting June 2021.)

  1. SBDs: The RBxx8 Series features (New products)

These SBDs provide low V F and high efficiency. Ten models of the PMDE package that have breakdown voltages of 30V up to 150V have been included in the RBxx8 series which provide extremely low I R (reverse current) and operate reliably even in extreme temperatures.

  • RBxx8 Series Lineup Table

  1. SBDs: RBR Series Features (Announced in August 2021)

The RBR series balances the trade-off relationship between low VF which is key to improving efficiency and low IR (mass produced since June 2020), 6 models in the series are available in the PMDE package.

  • RBR Series (PMDE Package) Lineup Table

  1. FRDs: RFN Series Features (New Products) 

FRDs provide high withstand voltage (up to 800V) equivalent to rectifier diodes along with excellent trr (reverse recovery time), which is important for high-frequency operation. The RFN series offers the same electrical characteristics as conventional products in a compact PMDE package.

  • RFN Series (PMDE Package) Lineup Table

  1. TVS: VS Series Features (New Products)

TVS is a type of diode that absorbs the sudden voltage (surge voltage) that flows during engine startup or breakdown, then steps down to a constant voltage. The VS series supports a wide range of standoff voltages (VRWM) from 5V to 130V.

(32 ranks of standoff voltages are offered between 5V and 130V)

  • VS Series (PMDE Package) Lineup Table

Pricing: $0.2/units (samples, excluding tax)

Availability: In mass production, through online distributors Digi-key, Mouser, and Farnell

Application Examples


AEC-Q101 Automotive Reliability Standard

AEC is the abbreviation as the acronym for Automotive Electronics Council, an organisation (comprised of major automobile component manufacturers and manufacturers) that is responsible for setting the standards of reliability for automotive electronic components. Q101 is a specific Q101 standards specifically applicable to semiconductor components that are discrete (i.e. diodes and transistors).

F. Forward Voltage F

A voltage drop is triggered when electricity flows in a upward direction from + to +. The lower the voltage drop is, the better the efficiency.

Reverse Current R

Reverse current is generated by applying reverse voltage. The lower the value the lower the amount of power consumed (reverse power loss).

Reverse Recovery Time TRR

The amount of time it takes the diode to change from an ON state to completely off. The shorter this time and the less loss it suffers when switching.


A huge amount of current or voltage suddenly happens. Events like surges, lightning, static electricity and even cranking at the start of the engine may occur in a variety of scenarios according to the specific application and, therefore, when creating circuits it is vital to incorporate protection circuits that do not be able to function in case of such unusual events.

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Michal Pukala
Electronics and Telecommunications engineer with Electro-energetics Master degree graduation. Lightning designer experienced engineer. Currently working in IT industry.