Microchip Technology 1N5243A

Overview

1N5243A from Microsemi is a 13 V, ±10% tolerance, 500 mW glass axial-lead Zener diode in DO-35 (DO-204AH) package, rated for 9.5 mA test current and 13 Ω dynamic impedance at 0.25 mA, 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 loops, and overvoltage protection.

For engineers reviewing the 1N5243A datasheet, 1N5243A pinout, 1N5243A application, or 1N5243A equivalent, key selection criteria include its 13 V nominal Zener voltage, ±10% tolerance (A suffix), 13 Ω Zener impedance at IZK = 0.25 mA, temperature coefficient of +0.079 %/°C, and DO-35 mechanical compatibility with axial-lead PCB layouts.

Technical Context

The 1N5243A operates as a reverse-biased silicon junction device with sharp Zener breakdown at 13 V under 9.5 mA test current. Its regulation stability relies on low dynamic impedance (13 Ω at 0.25 mA) and a positive temperature coefficient (+0.079 %/°C), indicating voltage increases with temperature - critical for thermal drift compensation in reference designs.

It is specified for operation across –65°C to +175°C with 250 °C/W junction-to-lead thermal resistance at 3/8″ lead length. The DO-35 hermetically sealed glass package ensures ESD insensitivity (MIL-STD-750 Method 1020) and minimal capacitance, supporting stable DC regulation without high-frequency coupling concerns.

Key Specifications

Pinout & Package

DO-35 (DO-204AH) hermetically sealed glass axial-lead package with cathode band marking. Leads are tin-lead or RoHS-compliant matte-tin plated, solderable per MIL-STD-750 Method 2026. Polarity: banded end = cathode (positive terminal during Zener operation).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N5243B and MMBZ5243B, the 1N5243A delivers optimal balance of cost, thermal robustness (250 °C/W), and axial-lead manufacturability for through-hole production, while its ±10% tolerance meets requirements in non-critical regulation and clamping roles.

Availability

1N5243A is available at Aetrix Electronics and suitable for power supply feedback, overvoltage protection, and low-power sensor biasing requiring stable component supply across extended temperature ranges and long-lifecycle programs.

Supply support for 1N5243A 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 1N52xx series was designed for military, aerospace, and industrial applications demanding proven JEDEC-standard Zener performance, hermetic reliability, and wide-temperature operation - not general-purpose consumer use.

FAQ

What is the nominal Zener voltage and tolerance of the 1N5243A?

The 1N5243A has a nominal Zener voltage of 13 V with a ±10% tolerance, meaning its actual breakdown voltage falls between 11.7 V and 14.3 V at 25°C and 9.5 mA test current. This tolerance is indicated by the "A" suffix per Microsemi's part numbering convention and is verified per JEDEC 1N52xx specifications.

What package type and marking does the 1N5243A use?

The 1N5243A uses the DO-35 (DO-204AH) hermetically sealed glass axial-lead package. It is marked with the full part number "1N5243A" on the body, and polarity is indicated by a cathode band on the banded end - which must be held positive relative to the anode for Zener operation.

What is the Zener impedance of the 1N5243A and why does it matter?

The 1N5243A has a Zener impedance of 13 Ω measured at IZK = 0.25 mA. This value reflects how tightly the device maintains its regulated voltage under varying load currents - lower impedance yields better regulation, especially in low-current or high-precision reference applications where small current changes must not cause significant voltage shifts.

Can the 1N5243A be used in high-temperature environments?

Yes, the 1N5243A is rated for operation from –65°C to +175°C and features a junction-to-lead thermal resistance of 250 °C/W at 3/8″ lead length. Its hermetic glass package and radiation-hardened construction make it suitable for downhole, avionics, and industrial control systems where sustained high-temperature reliability is mandatory.

How does the temperature coefficient of the 1N5243A affect circuit design?

The 1N5243A has a temperature coefficient of +0.079 %/°C, meaning its Zener voltage increases by approximately 10.3 mV per °C rise. Designers use this known drift to compensate other temperature-sensitive elements - for example, pairing it with a negative-tempco resistor network to achieve near-zero net drift in precision reference circuits.