Microchip Technology JANTX1N4959CUS/TR

Overview

JANTX1N4959CUS/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 11 V ±2% (C suffix), dynamic impedance of 2.5 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, overvoltage protection circuits, and biasing networks for aerospace and defense electronics.

For engineers reviewing the JANTX1N4959CUS/TR datasheet, JANTX1N4959CUS/TR pinout, JANTX1N4959CUS/TR application, or JANTX1N4959CUS/TR equivalent, this part is selected for its voidless-glass hermetic seal, Category I metallurgical bond, radiation-hardened construction per MicroNote 050, and MIL-PRF-19500/356 qualification - critical for mission-critical analog stabilization where leakage, thermal drift, and long-term parametric stability must be guaranteed.

Technical Context

This device operates in reverse-biased Zener breakdown mode, delivering stable regulation across 10%–50% of maximum Zener current (IZM = 430 mA) with voltage change ΔVZ ≤ 0.8 V. Its low dynamic impedance (2.5 Ω @ IZT = 125 mA) ensures minimal output variation under load transients, while triple-layer passivation and tungsten slug construction enhance moisture resistance and mechanical robustness.

The "E" package (D-5B) features copper end caps with Sn/Pb finish, cathode band polarity marking, and EIA-481-B tape-and-reel compliance. Thermal resistance is 7 °C/W junction-to-end-cap, enabling reliable 5 W operation up to 140 °C end-cap temperature before linear derating to zero at 175 °C.

Key Specifications

Pinout & Package

The JANTX1N4959CUS/TR uses the "E" package (also designated D-5B), a hermetically sealed voidless glass surface-mount case with tungsten slugs and copper end caps finished in Sn/Pb. Cathode is marked by a visible band on the glass body. No marking appears on the device surface per specification.

Key Features

Applications

Equivalent & Alternatives

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

Compared with JANTX1N4959CUS/TR, JANTXV1N4959CUS/TR adds verified radiation tolerance and extended reliability screening for space missions, while 1N4959US removes military qualification entirely - offering identical electrical specs but no assurance of performance under extreme environmental stressors.

Availability

JANTX1N4959CUS/TR is available at Aetrix Electronics and suitable for aerospace power conditioning, defense system reference voltage generation, and avionics overvoltage protection requiring stable component supply across extended lifecycle programs.

Supply support for JANTX1N4959CUS/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 analog and mixed-signal components for aerospace, defense, and industrial markets.

The JANTX1N4959CUS/TR belongs to Microsemi's legacy MIL-PRF-19500/356 qualified Zener series, designed specifically for voltage regulation and reference stability in mission-critical systems where failure is not an option.

FAQ

What is the Zener voltage tolerance of JANTX1N4959CUS/TR?

JANTX1N4959CUS/TR has a Zener voltage tolerance of ±2%, indicated by the "C" suffix in the part number. This corresponds to a nominal 11 V rating ranging from 10.78 V to 11.22 V at 125 mA test current and 25 °C ambient. The tolerance remains valid across the full –65 °C to +175 °C operating junction temperature range per MIL-PRF-19500/356 requirements. JANTX1N4959CUS/TR is therefore suited for applications demanding tighter regulation than standard ±5% Zeners.

Does JANTX1N4959CUS/TR require heatsinking in 5 W operation?

JANTX1N4959CUS/TR is rated for 5 W dissipation at an end-cap temperature (T_EC) of 140 °C, with a junction-to-end-cap thermal resistance of 7 °C/W. Heatsinking is not mandatory if PCB copper area and airflow maintain T_EC ≤140 °C; however, for sustained 5 W operation in enclosed or high-ambient environments, thermal vias and 1–2 in² of 2-oz copper are recommended. Derating begins linearly above 140 °C, reaching zero power at 175 °C. JANTX1N4959CUS/TR's glass package does not support clip-on heatsinks.

Is JANTX1N4959CUS/TR compatible with lead-free reflow processes?

JANTX1N4959CUS/TR features Sn/Pb (tin/lead) terminations per specification and is not qualified for lead-free reflow. Its maximum peak reflow temperature is limited to 235 °C for 30 seconds, below typical SAC305 (Sn-Ag-Cu) profiles peaking at 245–260 °C. Using JANTX1N4959CUS/TR in lead-free assembly risks solder joint fracture, glass-to-metal seal cracking, or end-cap finish degradation. For RoHS-compliant designs, consult Microchip's qualified lead-free alternatives or consider JANTX1N4959CUS/TR only in Sn/Pb-compatible lines. JANTX1N4959CUS/TR must not be subjected to lead-free thermal profiles.

What is the surge current rating of JANTX1N4959CUS/TR and how is it tested?

JANTX1N4959CUS/TR has a non-repetitive peak Zener surge current (I_ZSM) rating of 19 A for an 8.3 ms half-sine waveform, per MIL-STD-750 Method 3011. This rating reflects capability to absorb transient energy without parametric shift or physical damage. Testing is performed after preconditioning at maximum rated junction temperature. The value is derived from the device's 5 W power rating and thermal time constant - JANTX1N4959CUS/TR leverages its low thermal impedance (1.8 °C/W at 10 ms) to safely dissipate surge energy. Repeated surges must respect duty-cycle limits defined in the datasheet.

How does the radiation hardness of JANTX1N4959CUS/TR compare to commercial Zeners?

JANTX1N4959CUS/TR is radiation-hardened per Microsemi MicroNote 050, demonstrating total ionizing dose (TID) tolerance exceeding 100 krad(Si) with no significant Zener voltage shift or leakage increase. Commercial Zeners (e.g., 1N4959US) lack radiation characterization and typically degrade above 10 krad(Si). This makes JANTX1N4959CUS/TR suitable for low-earth-orbit satellites and nuclear-hardened platforms where cumulative radiation exposure would compromise unhardened devices. JANTX1N4959CUS/TR's voidless glass seal and Category I bond further mitigate displacement damage effects.