Silicon Carbide Diodes Increase Application Power Densities

Bourns is extending its product family of silicon carbide (SiC) Schottky barrier diode (SBD) with ten new high-voltage models (650 V and 1200 V) that will accommodate higher application power densities in emerging e-transportation, renewable energy, and industrial applications.   

 

New SiC Schottky barrier diode models. Image used courtesy of Bourns
 

Building on the company’s existing SiC SBD offering, the wide bandgap (WBG) models will improve performance in peak forward surge, forward voltage drop, thermal resistance, and efficiency. These characteristics allow greater power densities in the latest high-frequency power conversion applications.

The models are rated for currents ranging from 5 to 10 A with varying forward voltage and package options, including TO220-2, TO247-3, TO252, TO263, and TO247-2.

     

Schottky Barrier Diodes

Diodes are passive semiconductor components that allow current to pass in only one direction (forward bias). Diodes are an essential building block for the power rectifier and inverter circuits used in AC-DC switched mode power supplies (SMPS), solar inverters, electric motor drives, and other power conversion circuits.    

 

  

Schottky diode bridge rectifier used in an AC-DC power supply. Image used courtesy of Toshiba

 

An ideal diode would have no voltage drop during forward bias operation, zero leakage current when reversed bias (blocking current), and change nearly instantaneously between forward conduction and reverse blocking states.

The design of Schottky barrier diodes offers improvements over silicon junction diodes with lower forward voltage drops and reverse bias recovery currents that are closer to ideal. Silicon carbide (SiC) materials in these devices allow for much higher blocking voltages, faster switching speeds, and better thermal performance – all of which translate to more compact, efficient, and power-dense circuits.  

 

Constructing a SiC Schottky barrier diode. Image used courtesy of Bourns

 

Bourns constructs its SBDs with lightly doped n-type SiC material and a metal electrode made of aluminum or platinum. The metal electrode serves as the anode of the diode, while the n-type SiC substrate is the cathode.  
 

Reverse Recovery Time

A diode’s reverse recovery time is roughly the amount of time it takes to transition from a forward conduction state to a full reverse blocking state, and faster is better. When a diode transitions from the forward to reverse bias state, the charge between the metal electrode and semiconductor must be removed. 

 

Recovered charge vs. reverse voltage for a SiC SBD. Image used courtesy of Bourns

 

SiC Schottky diodes have about one-tenth the capacitance of silicon junction diodes, so they have a much lower amount of charge to be removed when transitioning to a reverse state. The result is a shorter reverse recovery time and better circuit operation.  

 

Forward Voltage Drop and Withstand Voltage

The new model extensions offer low forward bias voltage drops that simplify power system design while improving efficiency, performance, and predictability over temperature and other operating conditions.  

Higher bus voltages are essential for cutting-edge, high-power e-mobility and renewable energy applications to mitigate I2R current losses and meet system performance targets, such as efficiency, range, and operating life. Bourns’ new SiC SBD models support withstand voltages of 650 V and 1200 V, suitable to the needs of these latest high-voltage power conversion circuits.  

 

BSDV10G120E2 SiC SBD forward voltage characteristics. Image used courtesy of Bourns

 

Forward Power Dissipation

Along with power density, conversion efficiency is another headline specification in power conversion circuits. 

 

BSDV10G120E2 SiC SBD forward power dissipation. Image used courtesy of Bourns

 

The BSDV10G120E2 model (1200 V, 10 A) of the SiC SBD family offers low forward power dissipation to help meet overall system efficiency targets.