November 19, 2019
Ensuring stable operation under high temperature environments and contributing to lower power consumption and space savings in automotive systems
ROHM recently announced the availability of 200V ultra-low IR Schottky Barrier Diodes (SBD) optimized for automotive applications including powertrains and xEVs. The RBxx8BM/NS200 expands on the RBxx8 lineup of SBDs enabling high temperature operation that have already been proven in the automotive market in Japan. This new series offers ultra-low leakage current (IR) characteristics to achieve high withstand voltage of 200V. Replacing Fast Recovery Diodes (FRD) and rectifier diodes typically used in vehicle systems with ROHM's new SBDs make it possible to improve forward voltage (VF) characteristics significantly (11% lower than conventional FRDs). This reduces application power losses and allows smaller package designs by reducing heat generation, contributing to greater space savings.
In recent years, the technological trend in Drive Systems for 48V mild hybrids is mechanical integration, in which the motor and peripheral circuits are combined into a single module. This demands high efficiency and high voltage SBDs capable of stable operation at high temperatures. At the same time, higher voltage SBDs are required in systems utilizing conventional 150V components to increase functionality and reliability.
ROHM has been offering the RBxx8 lineup of ultra-low IR SBDs that withstand up to 150V compatible with high temperature automotive environments. This latest series adds 200V models to meet the new automotive requirements. ROHM will continue to enhance its lineup and contribute to lower power consumption and greater space savings in a wide range of applications in the industrial and automotive fields.
SBDs featuring superior efficiency are expected to replace conventional rectifier diodes and FRDs in automotive power supply exposed to high temperature. However, one drawback of SBDs is degraded IR characteristics at higher operating temperatures that can lead to thermal runaway, requiring products that provide stable operation at higher temperatures.
The RBxx8 series utilizes a barrier metal optimized for high temperature that significantly improves the IR characteristics (which is perhaps the most important challenge when using SBDs in automotive power supply). This ensures safe operation at high temperatures in automotive and industrial applications, eliminating the possibility of thermal runaway.
1. Replacing FRDs decreases application power consumption
Ultra-low IR allows ROHM to achieve high withstand voltage of 200V. This enables replacing 200V FRDs used in automotive systems with high efficiency SBDs. Therefore, the RBxx8BM/NS200 series reduces VF characteristics by 11% over conventional FRDs, contributing to lower application power losses.
2. Low heat generation reduces package size, contributing to greater space savings in a variety of applications
Reducing VF minimizes heat generation, enables users to adopt one smaller package size vs conventional solutions. ROHM is currently developing medium power packages, with plans to decrease mounting area by as much as 71% by replacing 5.9mm × 6.9mm FRDs with compact 2.5mm × 4.7mm products.
The addition of these eight new 200V models brings the total number of products in the RBxx8 lineup to 212.
Automotive applications (i.e. xEVs) such as powertrain, industrial inverters, and various types of power supplies
Reverse Current (IR)
Reverse current generated when reverse voltage is applied. The smaller this value is, the lower the power consumption.
Schottky Barrier Diode (SBD)
Characterized by low forward voltage drop and fast switching speed, SBDs are mainly used in switching power supplies.
A diode designed to convert AC to DC voltage.
Fast Recovery Diode (FRD)
A diode featuring fast reverse recovery time, which is the time it takes for the instantaneous current flowing in the reverse direction (generated when the voltage switches from the forward to the reverse direction) to reach zero.
Forward Voltage (VF)
The voltage generated in the diode when current flows in the forward direction. The smaller this value is, the lower the power consumption.