Microchip Technology 1N5247B

Overview

1N5247B from Microsemi is a 500 mW, 17 V ±5% glass axial-lead Zener diode in DO-35 (DO-204AH) package, designed for precision voltage regulation in low-power analog circuits, reference supplies, and overvoltage protection. It delivers 17 V nominal Zener voltage at 7.4 mA test current, with 600 Ω maximum Zener impedance at knee current and ±0.084 %/°C temperature coefficient.

For engineers reviewing the 1N5247B datasheet, 1N5247B pinout, 1N5247B application, or 1N5247B equivalent, key selection criteria include its tight 5% tolerance (B suffix), low thermal resistance (250 °C/W junction-to-lead), stable regulation across -65 °C to +175 °C, and compatibility with manual or wave soldering at 260 °C for 10 s.

Technical Context

The 1N5247B operates as a two-terminal reverse-biased silicon junction device, leveraging controlled avalanche breakdown to maintain stable output voltage under varying load and temperature conditions. Its Zener impedance is measured at both IZT (7.4 mA) and IZK (0.25 mA), ensuring sharp knee characteristics and rejection of unstable units.

It exhibits minimal capacitance (typical <2 pF at VR = 0 V, per Figure 2), nonsensitive ESD behavior (MIL-STD-750 Method 1020), and inherent radiation hardness per MicroNote 050 - making it suitable for aerospace, industrial, and high-reliability embedded systems where long-term parametric stability is critical.

Key Specifications

Pinout & Package

Hermetically sealed DO-35 (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. Mounting requires ≥10 mm (3/8″) lead length from body for rated thermal performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4742A and MMBZ5247B, the 1N5247B uniquely balances 17 V regulation, 500 mW axial-leaded power handling, JEDEC-standard DO-35 footprint, and radiation tolerance - making it irreplaceable in legacy industrial controls and aerospace retrofits requiring through-hole reliability.

Availability

1N5247B is available at Aetrix Electronics and suitable for industrial sensor reference, overvoltage clamp circuit, and programmable power supply feedback applications requiring stable component supply, long-lifecycle support, and traceable sourcing.

Supply support for 1N5247B 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 aerospace-grade components with deep heritage in discrete power and timing devices.

The 1N52xxB series was engineered for mission-critical voltage regulation in harsh environments - targeting defense electronics, satellite subsystems, and industrial control systems demanding guaranteed parametric stability over extended temperature and radiation exposure.

FAQ

What is the Zener voltage tolerance of the 1N5247B?

The 1N5247B has a nominal Zener voltage of 17 V with a guaranteed tolerance of ±5%, as indicated by the "B" suffix per JEDEC specification. This tolerance applies across the full operating temperature range of −65 °C to +175 °C and is verified at 7.4 mA test current under stabilized thermal conditions.

Can the 1N5247B be used in surface-mount designs?

No - the 1N5247B is packaged exclusively in the axial-leaded DO-35 (DO-204AH) glass case and is not a surface-mount device. For SMT equivalents with identical 17 V/±5% specs, consider the MMBZ5247B (SOT-23) or NZ9F17V (SOD-123), both requiring validation of thermal and mechanical compatibility in your layout.

What is the maximum steady-state power dissipation for the 1N5247B on a standard PCB?

When mounted on an FR4 board with 1 oz copper, 4 mm² pads, and 1 mm × 25 mm traces, the 1N5247B delivers 0.48 W steady-state power at TA < 25 °C. Derating begins above 25 °C at 3.2 mW/°C, reaching zero dissipation at 175 °C ambient - consistent with its specified thermal resistance of 310 °C/W junction-to-ambient.

Does the 1N5247B require external current limiting in Zener regulator circuits?

Yes - like all Zener diodes, the 1N5247B must be used with a series current-limiting resistor to prevent thermal runaway. The resistor value is calculated using (V_IN − 17 V) / I_Z, where I_Z is selected between 1 mA (minimum regulation) and 7.4 mA (rated test current), depending on load and stability requirements.

Is the 1N5247B compliant with RoHS directives?

Yes - the RoHS-compliant version is designated as 1N5247B-e3 and features annealed matte-tin plating per MIL-STD-750 Method 2026. Standard 1N5247B uses tin-lead plating; both versions share identical electrical and thermal specifications except for finish composition.