Microchip Technology 1N5240A

Overview

1N5240A from Microsemi is a 10 V, ±10% tolerance, 500 mW glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 20 mA test current, 600 Ω dynamic impedance at 20 mA, and operating across –65°C to +175°C. It serves as a precision voltage reference or shunt regulator in low-power analog circuits, power supply feedback paths, and overvoltage protection.

For engineers reviewing the 1N5240A datasheet, 1N5240A pinout, 1N5240A application, or 1N5240A equivalent, key selection criteria include its 10 V nominal Zener voltage with ±10% tolerance (A suffix), 600 Ω Zener impedance at I_ZT, thermal resistance of 250 °C/W junction-to-lead, and compatibility with manual or wave soldering at 260 °C for 10 s.

Technical Context

This discrete Zener diode operates in reverse breakdown to maintain stable voltage across a wide current range (0.25 mA to 20 mA), with minimal capacitance (<2.0 pF typical at 10 V) and inherent radiation hardness per MicroNote 050. Its DO-35 glass package provides hermetic sealing and ESD insensitivity per MIL-STD-750 Method 1020.

The device exhibits a positive temperature coefficient of +0.075 %/°C (25°C to 125°C, I_ZT = 20 mA), enabling predictable drift behavior in temperature-varying environments. Forward voltage is ≤1.5 V at 200 mA, supporting bidirectional testing and polarity verification during board-level validation.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) glass axial-leaded package with cathode indicated by a single black band; operated with banded end positive relative to unbanded end for Zener regulation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener regulation applications.

Compared with 1N5240A, the 1N4740A offers higher power handling and lower impedance but larger package and no radiation hardening; the BZX55-C10 delivers tighter tolerance and lower Z_ZT yet lacks inherent radiation hardness and military screening options.

Availability

1N5240A is available at Aetrix Electronics and suitable for voltage reference design, power supply feedback networks, and overvoltage protection circuits requiring stable component supply across aerospace, industrial control, and test equipment programs.

Supply support for 1N5240A includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and high-performance analog and mixed-signal components.

The 1N52xx series was designed for precision voltage regulation in mission-critical systems where long-term stability, wide temperature operation, and environmental robustness are essential.

FAQ

What is the nominal Zener voltage and tolerance of the 1N5240A?

The 1N5240A has a nominal Zener voltage of 10 V with a tolerance of ±10%, as indicated by the "A" suffix per JEDEC standards. This tolerance applies under specified test conditions of 20 mA current at 25°C ambient, and the device maintains regulation across its full operating temperature range of –65°C to +175°C. The 1N5240A is not rated for tighter tolerances like ±5% (B suffix) or ±1% (D suffix).

What package type and marking does the 1N5240A use?

The 1N5240A uses the DO-35 (DO-204AH) glass axial-leaded package with hermetic sealing and tin-lead or RoHS-compliant matte-tin plating. It is marked with the full part number "1N5240A" on the glass body, and polarity is indicated by a single black cathode band - the banded end must be held positive relative to the unbanded anode for proper Zener operation.

Can the 1N5240A be used in high-temperature environments?

Yes, the 1N5240A is rated for continuous operation from –65°C to +175°C, making it suitable for downhole drilling tools, avionics, and engine-control modules. Its thermal resistance is 250 °C/W junction-to-lead at 10 mm lead length, and derating begins above 25°C ambient - at 100°C ambient, maximum power drops to approximately 300 mW per Figure 1 in the datasheet.

Does the 1N5240A have radiation hardness certification?

Yes, the 1N5240A is inherently radiation-hardened per MicroNote 050, a documented characteristic of the 1N52xx family. This hardness is process-derived and does not require additional screening; it supports total ionizing dose (TID) resilience relevant to space and nuclear instrumentation applications, though specific TID values require consultation of MicroNote 050.

What is the Zener impedance and test condition for the 1N5240A?

The 1N5240A has a maximum Zener impedance (Z_ZT) of 600 Ω, measured at the 20 mA test current (I_ZT) and 60 Hz AC superimposed on DC bias. This value reflects dynamic resistance near the knee of the breakdown curve and directly impacts regulation accuracy under varying load currents - lower Z_ZT improves line and load regulation performance.