Microchip Technology 1N5240B/TR

Overview

1N5240B/TR from Microsemi is a 10 V, ±5% 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 IZK, and operating from –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 1N5240B/TR datasheet, 1N5240B/TR pinout, 1N5240B/TR application, or 1N5240B/TR equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (250 °C/W junction-to-lead), reverse leakage at VR = 7.6 V (≤30 µA), temperature coefficient (+0.075 %/°C), and RoHS-compliant "e3" availability with "TR" tape-and-reel packaging.

Technical Context

This discrete Zener diode operates in reverse breakdown mode with cathode band marking polarity. Its regulation performance is specified at 20 mA test current (IZT) and validated across –65°C to +175°C ambient, leveraging hermetically sealed glass construction for stable long-term voltage reference behavior.

Thermal design relies on junction-to-lead resistance (250 °C/W at 10 mm lead length) and derated power dissipation above 50°C. Capacitance is minimized per Figure 2 (typical <4 pF), supporting high-frequency stability in sensing and feedback loops without added filtering.

Key Specifications

Pinout & Package

Hermetically sealed DO-35 (JEDEC DO-204AH) glass axial-leaded package with cathode indicated by a single black band. Leads are tin-lead or RoHS-compliant matte-tin plated, solderable per MIL-STD-750 Method 2026. Weight: 0.2 g.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5240B/TR, 1N4740A offers higher power margin but requires layout changes due to DO-41 size, while BZX55C10 delivers superior dynamic regulation at lower test current but lacks radiation hardening and military screening options.

Availability

1N5240B/TR is available at Aetrix Electronics and suitable for power supply feedback reference, overvoltage clamp protection, and low-power analog sensor reference applications requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for 1N5240B/TR 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-temperature analog and mixed-signal components.

The 1N52xxB series was designed for precision voltage regulation in mission-critical systems including aerospace, defense, and industrial control, where long-term stability and extreme environmental resilience are mandatory.

FAQ

What is the Zener voltage tolerance of the 1N5240B/TR?

The 1N5240B/TR has a nominal Zener voltage of 10 V with a guaranteed tolerance of ±5%, as indicated by the "B" suffix per JEDEC specification. This means the actual measured VZ at 20 mA test current falls between 9.5 V and 10.5 V at 25°C. The tolerance remains valid across the full operating temperature range of –65°C to +175°C, though voltage drift is governed by the +0.075 %/°C temperature coefficient.

Can the 1N5240B/TR be used in surface-mount designs?

No, the 1N5240B/TR is a through-hole DO-35 axial-leaded device and is not surface-mount compatible. However, Microsemi offers the MLL5240B as a direct surface-mount equivalent in DO-213AA (MELF) package with identical electrical specifications. For SMT integration, specify MLL5240B/TR and verify land pattern compliance with JEDEC MO-127 standards.

What is the maximum reverse leakage current for the 1N5240B/TR?

The 1N5240B/TR has a maximum reverse leakage current (IR) of 30 µA when tested at VR = 7.6 V (0.76 × VZ), per the Electrical Characteristics table on page 2 of the Microsemi datasheet. This value is guaranteed for all units with "A" or "B" suffixes and reflects worst-case off-state conduction-critical for low-power bias networks and battery-backed circuits.

Does the 1N5240B/TR require heatsinking in typical applications?

No, the 1N5240B/TR does not require external heatsinking in standard 500 mW operation at ambient temperatures ≤50°C. Its thermal resistance is 250 °C/W junction-to-lead at 10 mm lead length, meaning a 125°C junction rise occurs at full 500 mW. Derating begins above 50°C (see Figure 1); at 70°C ambient, max power drops to ~350 mW. PCB copper area provides sufficient passive cooling for most designs.

Is the 1N5240B/TR suitable for aerospace applications?

Yes, the 1N5240B/TR is suitable for aerospace applications due to its radiation-hardened construction per MicroNote 050, –65°C to +175°C operating range, and availability in MIL-PRF-19500 screened versions (e.g., JANTXV-1N5240B with "MV" prefix). These variants undergo rigorous testing for total ionizing dose (TID), ELDRS, and burn-in, making them qualified for satellite power systems and avionics voltage references.