Microchip Technology JANS1N4993DUS/TR

Overview

JANS1N4993DUS/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 300 V ±5%, dynamic impedance of 950 Ω at 4 mA test current, and maximum reverse leakage of 2 μA at 228 V. It serves as a precision voltage reference and overvoltage clamp in radiation-hardened military power conditioning circuits.

For engineers reviewing the JANS1N4993DUS/TR datasheet, JANS1N4993DUS/TR pinout, JANS1N4993DUS/TR application, or JANS1N4993DUS/TR equivalent, this part is selected for high-reliability DC rail regulation where extended temperature operation (–65 °C to +175 °C), MIL-PRF-19500/356 qualification, and ESD insensitivity per MIL-STD-750 Method 1020 are mandatory.

Technical Context

This JANS1N4993DUS/TR belongs to the 1N4954US–1N4996US family of military-grade Zener regulators. Its voidless-glass construction uses Category I internal metallurgical bonds and triple-layer passivation to ensure long-term stability under thermal cycling and radiation exposure.

It operates across –65 °C to +175 °C junction temperature range with 10 °C/W thermal resistance (junction-to-end-cap), 1.5 V forward voltage at 1.0 A, and exhibits a positive temperature coefficient of +0.120 %/°C at 4 mA test current - critical for predictable drift in high-temperature avionics power rails.

Key Specifications

Pinout & Package

Package: Hermetically sealed voidless hard glass case with tungsten slugs; copper end caps with Sn/Pb finish; polarity indicated by cathode band; "E" package (also designated D-5B); 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 high-voltage Zener regulation applications.

Compared with JANS1N4993DUS/TR, JANTXV1N4993US provides identical electrical performance with reduced traceability and screening rigor, while 1N4993US omits all military qualifications and environmental hardening - making JANS1N4993DUS/TR the sole choice for deployed systems requiring guaranteed lifetime reliability.

Availability

JANS1N4993DUS/TR is available at Aetrix Electronics and suitable for aerospace power bus regulation, nuclear instrumentation bias supply, and military radar transmitter modulator applications requiring stable component supply under extended temperature, radiation, and shock/vibration stress.

Supply support for JANS1N4993DUS/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 emphasis on radiation-hardened and high-temperature operation.

The JANS1N4993DUS/TR belongs to Microsemi's legacy MIL-PRF-19500/356 qualified Zener regulator product line, engineered specifically for voltage reference and overvoltage protection in mission-critical power systems where failure is not an option.

FAQ

What is the Zener voltage tolerance for JANS1N4993DUS/TR?

JANS1N4993DUS/TR has a nominal Zener voltage of 300 V with a standard tolerance of ±5%, as specified in the Microsemi SD44A datasheet. This tolerance applies at 25 °C and I_ZT = 4 mA. No tighter tolerance suffix (e.g., 'C' or 'D') is present in the part number, confirming the ±5% rating. The JANS qualification does not alter this electrical specification.

Is JANS1N4993DUS/TR compatible with lead-free soldering processes?

JANS1N4993DUS/TR features copper end caps with Sn/Pb finish, making it incompatible with lead-free reflow profiles exceeding 220 °C peak temperature. Its glass package and metallurgical bonds are rated for traditional Sn63/Pb37 soldering per MIL-STD-202 Method 210. Lead-free assembly requires process validation and may void qualification unless explicitly approved in a Microsemi deviation notice.

What is the maximum continuous Zener current for JANS1N4993DUS/TR?

The maximum continuous Zener current (I_ZM) for JANS1N4993DUS/TR is 1.0 mA, derived from its 5 W power rating and 300 V Zener voltage (I_ZM = P_MAX/V_Z ≈ 5 W / 300 V ≈ 16.7 mA), but the datasheet specifies 1.0 mA as the absolute maximum continuous current at 25 °C - consistent with its 4 mA test current and thermal derating curve.

Does JANS1N4993DUS/TR require heatsinking in typical applications?

JANS1N4993DUS/TR has a thermal resistance of 10 °C/W (junction-to-end-cap) and is designed for conduction cooling via its end caps. In 5 W operation at 140 °C end-cap temperature, no external heatsink is required if mounted to a thermally conductive chassis or PCB copper pour meeting Microsemi's pad layout guidelines. Forced air or liquid cooling is unnecessary for rated conditions.

How is polarity identified on JANS1N4993DUS/TR?

JANS1N4993DUS/TR uses a cathode band to indicate polarity - a visible marking on the glass body adjacent to the cathode end cap. This band aligns with the cathode terminal in the "E" (D-5B) package outline. Correct orientation is critical: reverse connection will forward-bias the device at 1.5 V, potentially damaging downstream circuitry if current-limited improperly.