Why Review SiC Diodes

Silicon carbide junction barrier Schottky diodes are the quiet workhorses of modern power conversion. They carry the freewheeling and rectification current in power factor correction stages, solar inverters and electric vehicle chargers, and their value comes from what they do not do: they do not store minority charge, so they produce almost no reverse recovery. This review examines two CR Micro SiC JBS diodes from the perspective of an FAE who supports customers through design-in and bring-up, the CRXB08D065G3 and the CRXI10D065G2, both rated at 650 volts.

CRXB08D065G3: Third-Generation 650 V, 8 A

The CRXB08D065G3 is a third-generation 650 V, 8 A SiC JBS diode. The third generation refines the Schottky barrier and the junction geometry to lower forward voltage while keeping leakage under control at high temperature. At eight amperes it suits the rectifier position of compact adapters, auxiliary supplies and the boost stage of lower-power factor correction circuits. Its forward voltage is low enough that the conduction loss stays modest even in continuous conduction mode.

Forward Characteristics

The forward voltage rises gently with current and has a positive temperature coefficient at high current, which is the property that makes parallel operation safe. The datasheet curve, not a single number, tells the real story: read the curve at the current and the junction temperature your design will actually see. At twenty-five degrees the diode looks ideal; at one hundred and fifty degrees the forward voltage is higher but still predictable, and the negative coefficient at low current means current tends to spread across parallel devices.

Reverse Recovery and Capacitive Charge

A JBS diode has no minority carrier storage, so the reverse recovery charge is dominated by the junction and package capacitance rather than by stored charge. That means the recovery loss scales with voltage and frequency but stays far below a silicon PIN diode of the same rating. Measure the total capacitive charge on the datasheet and multiply by the bus voltage and the switching frequency to estimate the recovery loss.

CRXI10D065G2: Second-Generation 650 V, 10 A

The CRXI10D065G2 is a second-generation 650 V, 10 A SiC JBS diode. The second generation trades a slightly higher forward voltage for a robust and cost-effective process, which makes it a natural fit for high-volume rectification in power supplies and solar microinverters where the duty cycle is heavy and the budget is tight. The ten ampere rating covers boost and output rectifiers in the several-hundred-watt class.

Switching Behavior

Like the third-generation part, the CRXI10D065G2 produces negligible reverse recovery, so the diode can be used in hard-switched topologies without the recovery penalty that forces silicon designs toward soft switching. The tuning inductance and the snubber can be reduced, which simplifies the magnetics and lowers cost.

Capacitance and Ringing

Fast diodes ring with the parasitic inductance of the loop, so the device capacitance and the loop inductance set the ringing frequency and amplitude. Keep the loop short and, if necessary, add a small RC snubber. The goal is to keep the peak within the diode blocking margin without slowing the transition enough to create overlap loss.

Thermal Performance

Both diodes are rated for a high maximum junction temperature, which is essential because SiC devices are often used to raise power density that in turn raises temperature. Fit the thermal resistance from junction to case to the actual mounting, and account for the copper area around the package, because the board is part of the heatsink. Validate the thermal path with a thermocouple on the case and a calculated junction rise rather than trusting the package rating alone.

Application Fit

In power factor correction, either diode improves efficiency by removing recovery loss and allowing a higher switching frequency, which shrinks the boost inductor. In solar inverters, the low recovery loss and high temperature capability support the compact magnetics and sealed enclosures typical of string inverters. In electric vehicle chargers, the diodes rectify the secondary side and the power factor correction output, where efficiency and thermal margin both matter. Where a low-voltage bus is present, the CRXQ75M120G4Z can serve the higher-voltage switching position alongside these diodes.

Comparison and Selection

Choose the CRXB08D065G3 when the priority is the lowest forward voltage in a compact rectifier at moderate current, and choose the CRXI10D065G2 when the priority is a rugged, cost-effective rectifier for high-volume, high-duty designs. In both cases confirm the current waveform, the junction temperature and the loop inductance before committing, because a diode that is correct on paper can be wrong in a bad layout.

Summary

The CRXB08D065G3 and CRXI10D065G2 deliver the classic SiC diode benefits of negligible reverse recovery, high temperature capability and safe parallel operation in two price and performance points. Measure the forward curve at your operating point, estimate the capacitive recovery loss, engineer the thermal path, and keep the commutation loop short. A simple efficiency sweep across load, from ten percent to full load and at both temperature extremes, quickly confirms whether the diode is operating where the datasheet predicts. If the measured loss is higher than the estimate, recheck the loop inductance and the forward-voltage curve before blaming the diode. That is enough to get the most from either device.