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2017.04.06 SiC Power Device

What are SiC Schottky barrier diodes? - Evolution of SiC-SBDs

SiC Schottky Barrier Diode

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Up to this point, we have explained the characteristics of SiC-SBDs, for reference in comparison with Si diodes. As part of this discussion, we have described how SiC-SBDs have themselves evolved into a second generation, with steadily advancing performance, and with third-generation devices announced. Here we will summarize the evolution of SiC-SBDs and briefly describe their current status and the SiC-SBDs that can actually be acquired.

In the case of power supply ICs and the like, different manufacturers offer products that vary in architecture and built-in functions, but when it comes to discrete devices such as diodes and transistors, there is no difference in the functions of the device itself, and so what are essentially common characteristic parameters can be compared directly when selecting components. In doing so, knowing the device variations can probably shorten the time required for design.

Evolution of SiC-SBDs

ROHM's current SiC-SBDs are mainly second-generation devices, and 50 models are already being mass-produced and provided. The following graph indicates the forward voltage and current characteristics (VF vs. IF), as well as the forward voltage and maximum allowable surge current (VF vs. IFSM), for the first through third generations.

SiC_2-4_vf
SiC_2-4_IFSM

Through innovations in manufacturing processes, second-generation SiC-SBDs retain leakage currents and trr performance comparable to previous devices while lowering VF by approx. 0.15 V. As a result, VF-induced conduction losses are improved.

In the third generation, a JBS (Junction Barrier Schottky) structure was adopted with the aim of improving the maximum allowable surge current (IFMS) and leakage current (IR). The JBS structure essentially is effective with respect to IFSM and IR, but in addition the low-VF characteristic achieved in the second generation was further improved. Typical values at Tj=25℃ are the same, but at Tj=150℃, VF is reduced 0.11 V compared with second-generation devices. That is, there are further advantages for operation under high-temperature conditions. Below are a graph of the reverse voltage VR versus the reverse (leakage) current IR, and a table comparing numerical values of improved parameters, for second- and third-generation SiC-SBDs.

SiC_2-4_if
SiC_2-4_tbl

To gain an understanding of the VF temperature characteristic, we present graphs excerpted from data sheets. The graph on the left is for the second-generation SCS210AG, and that on the right is for the third-generation product SCS310AP, both at 650 V/10 A. We see that the third-generation product has a steep VF-IF curve gradient at high temperatures and a lower VF for the same IF, an improvement over the second-generation device.

vf210_vf310

Currently Available Lineup and Development Plans

Below are currently available second-generation and third-generation products. Models are being added continuously to both product groups. They should be useful for confirming separate product specifications. In addition, data sheets can be accessed here.

2nd Generation SiC-SBDs
SiC_2-4_2Gtable

3rd Generation SiC-SBDs
SiC_2-4_3Gtable

Key Points:

・ROHM SiC-SBDs have already evolved to the third generation.

・Third-generation products offer improved TFMS and reduced leakage currents, and further reduce the low VF values achieved in the second generation.

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