Microchip Technology JANTX1N4958CUS/TR

Overview

JANTX1N4958US/TR from Microsemi is a military-qualified, hermetically sealed surface-mount Zener diode rated for 5 W power dissipation at 140 °C end-cap temperature, with nominal Zener voltage of 10.0 V ±5%, dynamic impedance of 2.0 Ω at 125 mA test current, and operating junction temperature range from –65 °C to +175 °C. It serves as a precision voltage reference and regulation element in high-reliability power supply rails, analog front-ends, and overvoltage protection circuits for aerospace and defense systems.

For engineers reviewing the JANTX1N4958US/TR datasheet, JANTX1N4958US/TR pinout, JANTX1N4958US/TR application, or JANTX1N4958US/TR equivalent, this part delivers verified MIL-PRF-19500/356 compliance, voidless-glass hermetic sealing, Category I metallurgical bonding, and radiation-hardened behavior per MicroNote 050 - critical for mission-critical voltage stabilization under extreme thermal and radiation stress.

Technical Context

This Zener operates in reverse breakdown mode with tightly controlled V_Z = 10.0 V at I_ZT = 125 mA, exhibiting ΔV_Z ≤ 1.0 V between 10% and 50% of I_ZM. Its low dynamic impedance (2.0 Ω) ensures stable regulation across load transients, while its 7 °C/W junction-to-end-cap thermal resistance supports reliable 5 W operation when mounted on thermally optimized PCB pads.

The device uses a tungsten-slug glass package with copper end caps and Sn/Pb finish, cathode marked by band, and conforms to EIA-481-B tape-and-reel packaging. It is nonsensitive to ESD per MIL-STD-750 Method 1020 and exhibits inherent radiation hardness without external shielding.

Key Specifications

Pinout & Package

Package: Hermetically sealed voidless glass "E" package (also designated D-5B), with two axial end-cap terminals. Cathode identified by black band. Weight: 539 mg. Tape-and-reel compliant per EIA-481-B.

Key Features

Applications

Equivalent & Alternatives

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

Compared with JANTXV1N4958US, the JANTX1N4958US/TR offers full MIL-PRF-19500/356 compliance at lower cost and shorter lead time, while the commercial 1N4958US lacks radiation assurance and lot traceability - making JANTX1N4958US/TR the optimal balance of assured reliability and procurement agility for Tier-1 defense subcontractors.

Availability

JANTX1N4958US/TR is available at Aetrix Electronics and suitable for aerospace power conditioning, defense system reference, and downhole instrumentation requiring stable component supply across extended temperature and radiation environments.

Supply support for JANTX1N4958US/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) designs high-reliability analog and mixed-signal components for aerospace, defense, and industrial markets, with emphasis on radiation-hardened, high-temperature, and hermetically sealed solutions.

The JANTX1N4958US/TR belongs to Microsemi's legacy MIL-PRF-19500/356 qualified Zener series, engineered specifically for voltage regulation in mission-critical systems where failure is not an option - including launch vehicles, tactical radios, and nuclear instrumentation.

FAQ

What is the Zener voltage tolerance for JANTX1N4958US/TR?

The JANTX1N4958US/TR has a nominal Zener voltage of 10.0 V with a standard tolerance of ±5%, as specified in the SD44A datasheet. This tolerance applies at the test current I_ZT = 125 mA and ambient temperature of 25 °C. No suffix letter (e.g., "C" or "D") is present in the part number, confirming the ±5% grade. The JANTX1N4958US/TR does not include tighter tolerances unless explicitly marked with a C (±2%) or D (±1%) suffix.

Does JANTX1N4958US/TR require derating above 140 °C?

Yes, JANTX1N4958US/TR must be derated linearly above an end-cap temperature (T_EC) of 140 °C, reaching zero power dissipation at 175 °C. The derating slope is –35.7 mW/°C, calculated from 5 W over 35 °C. This requirement is defined in the Maximum Ratings table of the SD44A datasheet and applies regardless of mounting method or PCB copper area, due to the fixed thermal resistance of 7 °C/W junction-to-end-cap.

Is JANTX1N4958US/TR compatible with lead-free solder reflow?

No, JANTX1N4958US/TR features a tin/lead (Sn/Pb) termination finish and is not qualified for lead-free reflow profiles. Its end caps are plated with Sn/Pb per the SD44A datasheet, and exposure to peak temperatures ≥260 °C (typical for Pb-free processes) risks intermetallic formation and bond degradation. For Pb-free assembly, Microsemi recommends evaluating the newer Microchip-qualified equivalents or consulting application note AN-1127 for validated thermal profiles.

What is the surge current rating for JANTX1N4958US/TR?

JANTX1N4958US/TR is rated for a nonrepetitive peak Zener surge current (I_ZSM) of 20 A under an 8.3 ms half-sine wave condition, as confirmed in the Electrical Characteristics table on page 2 of SD44A. This rating reflects single-event survivability - not repetitive duty - and assumes proper PCB thermal mass and minimal trace inductance to limit voltage overshoot during surge onset.

How is polarity marked on JANTX1N4958US/TR?

JANTX1N4958US/TR uses a cathode band for polarity identification: a single black band located adjacent to the cathode end-cap. This marking is consistent across all 1N49xxUS devices and aligns with JEDEC standard DO-213AA outline. The anode is the unmarked end-cap. Visual inspection under 10× magnification confirms band placement, and automated optical inspection (AOI) systems use this band for orientation verification during SMT placement.