MXLPLAD36KP75A

FAQFrequently Asked Questions

• What is the reverse standoff voltage rating of the MXLPLAD36KP75A, and how does it affect circuit protection strategy? The MXLPLAD36KP75A has a reverse standoff voltage (Vrwm) of 75V, meaning the diode remains non-conducting below this threshold. In your design, this rating determines the maximum safe operating voltage under normal conditions. If your signal or supply line can experience transients above 75V, the MXLPLAD36KP75A will begin conducting to divert energy; however, if your application regularly sees voltages near or exceeding 75V in steady state, this device may conduct continuously and dissipate excessive power, requiring reconsideration of the protection architecture or selection of a higher-rated TVS diode.
• Can the MXLPLAD36KP75A clamp a transient to a safe level for downstream components rated below 121V? The MXLPLAD36KP75A clamps voltage to a maximum of 121V at peak pulse current (Ipp) of 298A. If your protected circuit contains logic or analog components with absolute maximum ratings below 121V, this clamping voltage may still cause damage. You must verify that all downstream components tolerate 121V; if they do not, the MXLPLAD36KP75A may not provide adequate protection for that application, and a lower-clamp TVS or series resistance may be necessary.
• How should the MXLPLAD36KP75A be selected when replacing or migrating from a through-hole TVS diode to surface mount? The MXLPLAD36KP75A uses a nonstandard SMD PLAD package, which differs from common DO-214 or leadframe packages. Before replacing an existing through-hole or conventional SMD TVS, confirm that your PCB layout, via structure, and thermal path can accommodate the PLAD footprint and that your manufacturing process supports this package type. The MXLPLAD36KP75A's 36kW peak pulse power rating and 298A current capability mean it is typically chosen for higher-energy transient events; if your legacy design used a lower-power TVS, the MXLPLAD36KP75A may introduce unnecessary cost or complexity unless the threat environment has changed.
• Is the MXLPLAD36KP75A suitable for continuous overvoltage protection on a 48V power bus? No. The MXLPLAD36KP75A is designed for transient suppression, not continuous overvoltage regulation. Its 75V reverse standoff voltage is intended for suppression of fast transients (nanosecond to microsecond timescale) on systems with a nominal operating voltage well below 75V. If your 48V bus experiences sustained overvoltages at or above 75V, the MXLPLAD36KP75A will conduct continuously, generating heat and potentially failing. For continuous overvoltage protection on 48V rails, use a voltage regulator, supervisor IC, or active clamp circuit instead.
• What thermal management considerations apply to the MXLPLAD36KP75A during repetitive transient events? The MXLPLAD36KP75A is rated for 36kW peak pulse power with an operating junction temperature range of -55°C to 150°C. While a single 10/1000µs transient dissipates energy within the pulse duration, repetitive transients accumulate heat in the die. The PLAD package's thermal impedance to ambient and board depends on PCB copper area, via placement, and solder joint quality. In high-frequency or high-energy transient environments (e.g., industrial switching circuits, automotive load-dump), ensure adequate thermal coupling to ground or power planes; if the MXLPLAD36KP75A junction temperature approaches 150°C during repetitive events, reliability may degrade, and parallel or distributed TVS placement should be considered.
• Can the MXLPLAD36KP75A be used in a series-parallel protection scheme, and what are the trade-offs? Yes, multiple MXLPLAD36KP75A diodes can be paralleled to increase peak current handling or placed in series with other protection stages (such as a fuse or resistor). Parallel devices share transient current, reducing individual power dissipation and junction temperature rise. However, parallel TVS diodes may have slightly different reverse characteristics due to manufacturing variation; to ensure balanced sharing, keep PCB traces to each diode equal length and minimize loop inductance. Series placement (e.g., MXLPLAD36KP75A in series with a current-limiting resistor) reduces peak current but increases clamping voltage, so verify that your protected circuit tolerates the combined effect.
• Is the MXLPLAD36KP75A MIL-PRF-19500 qualification suitable for aerospace or high-reliability applications? The MXLPLAD36KP75A carries MIL-PRF-19500 qualification, which indicates it meets military-grade screening and reliability standards. This qualification is relevant for aerospace, defense, and critical infrastructure applications where component traceability, burn-in, and failure-rate data are mandatory. However, MIL-PRF-19500 qualification does not automatically approve the MXLPLAD36KP75A for a specific program; you must verify that the device's part number and qualification date align with your program's approved component list (ACL) and that procurement includes required certifications (test reports, material certs, traceability documentation).
• What are the lead-free and environmental compliance implications of the MXLPLAD36KP75A? The MXLPLAD36KP75A is RoHS non-compliant, meaning it may contain lead or other restricted substances. For applications in regions with strict RoHS mandates (EU, China), this device may not be acceptable without a formal exemption or alternative compliance pathway. Verify your customer requirements and end-market regulations before design-in. If RoHS compliance is mandatory, consult Microchip's product portfolio for a compliant TVS alternative with similar electrical ratings; substitution may involve re-qualification and PCB layout changes.
• How does the MXLPLAD36KP75A's breakdown voltage minimum (83.3V) differ from its reverse standoff (75V), and what does this mean for transient response? The reverse standoff voltage (Vrwm) of 75V is the maximum voltage at which the MXLPLAD36KP75A remains essentially non-conducting in normal operation. The breakdown voltage minimum (VBR) of 83.3V is the threshold at which the diode enters active conduction under controlled test conditions. Between 75V and 83.3V, the diode exhibits soft-turn-on behavior with increasing leakage current. This slope region allows the MXLPLAD36KP75A to respond dynamically to transients; a very fast transient spike may reach above 83.3V, triggering rapid conduction and clamping before damage occurs. Understanding this window is critical for circuits operating near the standoff voltage, where marginal transients could be suppressed or could slip through, depending on transient rise time and energy.
• Can the MXLPLAD36KP75A be used in AC or bipolar transient environments, or is it suitable only for unidirectional (DC) suppression? The MXLPLAD36KP75A is a unidirectional (single-channel) TVS diode, meaning it conducts only in one polarity direction. It is designed for DC or unidirectional transient suppression. If your application experiences bidirectional or AC transients (e.g., differential signaling lines, transformer secondary spikes, AC power distribution), a single MXLPLAD36KP75A will protect against transients in only one polarity. For bidirectional protection, you must place two MXLPLAD36KP75A diodes back-to-back in opposite polarity orientation, effectively doubling the footprint and component cost; alternatively, use a dedicated bidirectional TVS array designed for AC applications.
• How does the MXLPLAD36KP75A perform under cold-soak or thermal-shock conditions in military or aerospace environments? The MXLPLAD36KP75A's operating temperature range is -55°C to 150°C (TJ junction temperature). Military and aerospace applications often demand rapid thermal cycling (e.g., -55°C to +125°C at 10 cycles per hour). The PLAD nonstandard SMD package and solder joints experience mechanical stress during thermal cycling, which can lead to interconnect fatigue or package failure over time. MIL-PRF-19500 qualification includes thermal-cycling test protocols; however, you should obtain the device's lot-specific thermal-shock and vibration qualification reports from your supplier and verify that the MXLPLAD36KP75A meets your program's additional reliability testing (e.g., HALT, HASS, or thermal-vacuum cycling).
• What is the capacitance of the MXLPLAD36KP75A, and could it affect high-speed signal integrity? The MXLPLAD36KP75A's capacitance data is not specified in the datasheet (listed as "-"). Typical TVS diodes in this voltage class exhibit junction capacitance in the range of 50–200 pF. Even though the exact value is not published, the presence of parasitic capacitance means the MXLPLAD36KP75A will load high-speed signal lines (e.g., GHz-range digital signals or RF traces). If you are protecting ultra-high-speed signals (>1 GHz), the undisclosed capacitance may introduce timing skew or signal distortion. Contact Microchip for the capacitance datasheet or conduct board-level measurements; if capacitive loading is unacceptable, consider low-capacitance TVS alternatives or shielded/isolated transient suppression topologies.