Articles

A resistor delivering 10 mA to a shunt node cannot simultaneously supply a 10 mA load and leave 5 mA in the Zener. The current must divide. That simple balance explains why a circuit that looks stable with no load can sag when a load is connected. A Zener regulator is therefore a current-budget exercise … Read more

The proposed replacement reaches the old pads only if its leads sit at their edges. Its catalog pulse rating is higher, but the current-return route is longer. That is not yet a protection upgrade; it is a different assembly with an unverified clamp path. For an SMD TVS diode, start with the transient and voltage … Read more

One board stops powering up after an event; another still runs but has lost its intended protection path. A shorted shunt and an open protection path can explain those different outcomes. Normal operation alone cannot establish that a TVS remains healthy. The comparison below is a hypothetical repair review, not a report of customer failures. … Read more

“3KP” is not a promise that a small axial component can dissipate three kilowatts continuously. In the referenced families it identifies a peak-pulse class tied to a defined waveform. Omitting that condition turns a useful family code into a misleading power claim. For a buyer or engineer investigating 3KP43, separate the family, voltage row, suffix, … Read more

A 1 mA breakdown test and a surge test at tens of amperes ask different questions. A TVS can pass the first without that result proving its behavior in the second. Keep that distinction visible before deciding that a removed protection part is reusable. For repair work, the immediate objective is often narrower: locate a … Read more

A protection part is marked D7 on the board, and the schematic shows a bent cathode line. That does not tell you whether the part is a Zener reference, a unidirectional TVS, or a generic library symbol assigned to something else. The device label and source document must settle the question. For a reader tracing … Read more

Consider two design reviews. One concerns a supply-line surge absorber with thermal disconnection; the other concerns a sensitive DC input with a narrow voltage allowance. Both need transient protection, but a matching word such as “surge” does not make the components interchangeable. These are hypothetical comparison scenarios. For a buyer preparing alternatives, the useful checklist … Read more

A TVS with the right voltage printed in its name can still let the protected circuit see too much voltage. A higher-power replacement may survive the pulse while the downstream IC fails. Those outcomes are consistent when the original selection confused working voltage with clamping voltage. This guide approaches selection through those failure checks. Start … Read more

A 5 V source across 100 Ω would initially supply 50 mA in an ideal resistive calculation. That is already enough to show why “100 Ω protects any microcontroller pin” is an unsafe assumption. The real output stage has its own impedance, voltage behavior, and current limits. The resistor can still be a reasonable candidate … Read more

The gate trace shows several oscillations after turn-on. Before ordering a larger resistor or rejecting the MOSFET, shorten the probe connection and repeat the measurement. If the displayed ringing changes substantially, part of the problem may be the measurement loop. For an engineer or buyer reviewing an alternative device, that first distinction matters. A transistor … Read more

Consider two three-lead transistors in similar TO-92 bodies. In the referenced onsemi 2N3904 document, pin 1 is emitter. In the referenced onsemi BC547 document, pin 1 is collector. The same-looking housing has not preserved the electrical assignment. This is a documented pin-map comparison, not an assertion that the two devices are substitutes. It establishes a … Read more

A larger avalanche-energy number does not necessarily identify the more suitable MOSFET. One figure may be measured at a different current, starting temperature, or test inductance. A comparison that hides those conditions can reverse the practical conclusion. The engineering cost is the missing analysis: where the spike’s energy goes, how often the event occurs, and … Read more