James

A MOSFET and a BJT can both switch the same load in many circuits, and choosing between them comes down to what the rest of the circuit asks. The BJT is a current-controlled valve: it turns on with base current, and its on-state drop stays relatively fixed. The MOSFET is a voltage-controlled gate: it turns … Read more

Welding and induction heating are the harshest IGBT duties outside the motor drive, because both throw high-current pulses at the device faster and harder than a steady load ever does. A welder draws a current spike at every arc strike; an induction heater switches at high frequency against an inductive coil. Both punish the IGBT … Read more

The four-diode bridge is the default rectifier topology for a reason, but it is not the only arrangement in the family. Center-tapped full-wave circuits, voltage-doubler stages, and common-cathode diode pairs all appear in real power supplies, and each one trades diodes, transformer windings, and stress in a different way. Understanding the family — what the … Read more

A bridge rectifier inside a power supply fails in one of a handful of ways, and the evidence is usually visible before a single meter lead touches the board. Burn patterns around the leads, a body split by thermal stress, a rail that sags after being fine, or smoke that only appears under load — … Read more

Transistors are the diodes that never quite behave like diodes. A transistor datasheet describes a three-terminal device with gain, saturation, and switching behavior, and the multimeter test that works for a plain diode only takes you part of the way. Still, a surprising amount of transistor diagnosis reduces to one model — the transistor seen … Read more

Small-signal diodes are everywhere in a board — logic inputs, I/O protection, level shifters, and switching trains — and their datasheet rarely tells you the thing you actually need to know. The reverse-recovery time is quoted, but what matters in a logic or switching circuit is how the diode blurs or clips a real signal, … Read more

A MOSFET datasheet quotes an RDS(on) at 25 °C, and the part on your board runs at 100 °C — where its on-resistance has climbed to nearly double and the conduction loss has grown by the square of any current increase. The temperature that raises its own resistance is the central reality of MOSFET thermal … Read more

A Schottky diode is supposed to be a low-voltage part — the silicon Schottky’s barrier is low, its reverse voltage is modest, and its leakage climbs with temperature. So the existence of a 1700 V SiC Schottky barrier diode (SBD) looks like a contradiction until the material is changed. Silicon carbide carries the low forward … Read more

Silicon carbide comes in two discrete forms a designer must choose between — the SiC Schottky barrier diode (SBD) and the SiC MOSFET — and the choice is not about which material is better but which device the duty needs. A diode conducts in one direction and blocks the other; a MOSFET switches on command. … Read more

Silicon carbide MOSFETs are presented as the future of power electronics, and a large share of the enthusiasm is not backed by the loss math. The honest picture is that SiC MOSFETs improve exactly three things — conduction loss at high temperature, switching loss at high dv/dt, and voltage class — and every other claim … Read more