Microchip Technology JANS1N4985CUS/TR

Overview

JANS1N4985CUS/TR from Microsemi is a hermetically sealed, voidless-glass surface-mount Zener diode rated for 5 W power dissipation at 140 °C end-cap temperature, with nominal Zener voltage of 130 V ±5%, dynamic impedance of 190 Ω at 10 mA test current, and operating junction temperature range from –65 °C to +175 °C. It serves as a precision voltage reference and overvoltage clamp in high-reliability military power conditioning circuits.

For engineers reviewing the JANS1N4985CUS/TR datasheet, JANS1N4985CUS/TR pinout, JANS1N4985CUS/TR application, or JANS1N4985CUS/TR equivalent, key selection criteria include its MIL-PRF-19500/356 qualification, radiation-hardened construction, Category I metallurgical bond, and 130 V regulation stability across wide current (1–98.8 mA) and thermal extremes.

Technical Context

This device belongs to Microsemi's JANS-qualified 1N4954US–1N4996US family, designed for space- and defense-grade applications requiring zero-failure tolerance. Its voidless-glass hermetic seal and triple-layer passivation ensure long-term reliability under thermal cycling, humidity, and radiation exposure.

The JANS1N4985CUS/TR uses an "E" package (D-5B outline) with tungsten slugs and copper end caps finished in Sn/Pb. Its Zener breakdown exhibits low temperature coefficient (+0.105 %/°C), stable regulation ΔVZ ≤11 V between 10% and 50% of IZM, and surge capability up to 1.8 A (8.3 ms square wave).

Key Specifications

Pinout & Package

The JANS1N4985CUS/TR uses the "E" package (also designated D-5B), a surface-mount hermetic glass case with two axial end-cap terminals. Cathode is marked by a band on the glass body. The package has no internal leads; electrical connection is made directly via metallized end caps soldered to PCB pads per Microsemi's recommended pad layout.

Key Features

Applications

Equivalent & Alternatives

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

Compared with JANS1N4985CUS/TR, JANTXV1N4985CUS/TR offers identical performance with reduced screening rigor, while 1N4985CUS/TR omits radiation hardness and extreme-temperature validation-making both unsuitable as drop-in replacements in flight hardware without requalification.

Availability

JANS1N4985CUS/TR is available at Aetrix Electronics and suitable for aerospace power bus protection, defense radar bias supply, and nuclear instrumentation signal conditioning requiring stable component supply across extended product lifecycles and obsolescence-sensitive programs.

Supply support for JANS1N4985CUS/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 semiconductors for aerospace, defense, and industrial markets, with core expertise in radiation-hardened and hermetically sealed components.

The JANS1N4985CUS/TR belongs to Microsemi's legacy MIL-PRF-19500/356 Zener regulator family, engineered specifically for zero-failure-tolerance voltage reference and transient suppression in mission-critical electronic systems.

FAQ

What is the Zener voltage tolerance and test current for JANS1N4985CUS/TR?

The JANS1N4985CUS/TR has a nominal Zener voltage of 130 V with ±5% tolerance, measured at a test current (I_ZT) of 10 mA. This tolerance reflects the standard specification for the "CUS" suffix variant and is verified per MIL-PRF-19500/356 screening requirements. The device maintains regulation within this band across its full operating temperature range.

Is JANS1N4985CUS/TR compatible with lead-free soldering processes?

JANS1N4985CUS/TR features Sn/Pb-finished copper end caps and is qualified for traditional eutectic solder reflow. While it can survive lead-free peak temperatures (≤260 °C), Microsemi does not guarantee performance or reliability under Pb-free assembly due to absence of Pb-free qualification testing. For JANS1N4985CUS/TR, use Sn63/Pb37 or Sn62/Pb36/Ag2 reflow profiles per Microsemi's application note AN-102.

Does JANS1N4985CUS/TR require derating above 140 °C end-cap temperature?

Yes. JANS1N4985CUS/TR is rated for 5 W dissipation only at T_EC = 140 °C. Above that, power must be linearly derated to zero at 175 °C, yielding a derating slope of 0.143 W/°C. At 155 °C end-cap temperature, maximum allowable continuous power drops to 2.86 W. This derating applies regardless of ambient or board-level cooling method.

What is the maximum reverse leakage current for JANS1N4985CUS/TR at 104 V?

The maximum reverse leakage current (I_R) for JANS1N4985CUS/TR is 2 μA when measured at V_R = 104 V and T_A = 25 °C. This value is guaranteed per MIL-PRF-19500/356 Group A testing and remains ≤5 μA across the full –65 °C to +125 °C operating range, supporting ultra-low-power standby modes in battery-operated systems.

How is polarity indicated on the JANS1N4985CUS/TR package?

JANS1N4985CUS/TR uses a cathode band - a single opaque black or dark-gray circumferential stripe near one end of the glass body - to identify the cathode terminal. The unmarked end is the anode. This marking complies with JEDEC standards and is visible under 10× magnification; no laser marking or alphanumeric codes are present on the device.