Microchip Technology 1N4460CUS/TR

Overview

1N4460CUS/TR from Microsemi is a military-qualified, hermetically sealed MELF surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with a nominal Zener voltage of 6.2 V at 40 mA test current, ±2% tolerance (indicated by 'C' suffix), and operating junction temperature range of –65 °C to +175 °C. It serves as a precision voltage reference and regulator in high-reliability aerospace, defense, and industrial control systems where failure is not tolerable.

For engineers reviewing the 1N4460CUS/TR datasheet, 1N4460CUS/TR pinout, 1N4460CUS/TR application, or 1N4460CUS/TR equivalent, key selection criteria include its voidless glass construction, Category 1 internal metallurgical bond, MIL-PRF-19500/406 qualification (JANTXV level available), thermal resistance of 20 °C/W (junction-to-end cap), and ESD immunity per MIL-STD-750 Method 1020.

Technical Context

This device operates in reverse breakdown to maintain stable voltage across wide current (0.5–3.72 mA minimum to 230 mA maximum continuous) and temperature ranges. Its Zener voltage exhibits low dynamic impedance (4 Ω at 40 mA) and tightly controlled knee impedance (200 Ω at 0.5 mA), enabling accurate regulation near the breakdown threshold.

The 1N4460CUS/TR uses a hard-glass, voidless hermetic package with tungsten slugs and tin/lead terminations, supporting solder reflow up to 260 °C for 10 s. Its thermal impedance profile (per Figure 4) is optimized for pulsed surge handling, with peak ZθJX ≈ 120 °C/W at 10 ms, reflecting robust transient energy absorption capability.

Key Specifications

Pinout & Package

Package: A-size MELF (D-5A) - cylindrical glass body with axial metallized end caps; dimensions: BD = 0.091–0.103 in (2.31–2.62 mm), BL = 0.168–0.200 in (4.28–5.08 mm); weight = 193 mg; polarity marked by cathode band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4460CUS/TR, the 1N4460US offers identical form and function at reduced tolerance and cost, while the 1N4460TR sacrifices military reliability and hermeticity for standard through-hole mounting - neither is pin-compatible due to differing packages, and both require layout revision if substituted.

Availability

1N4460CUS/TR is available at Aetrix Electronics and suitable for avionics power conditioning, satellite onboard regulators, and tactical radio transceiver biasing requiring stable component supply, full traceability, and long-term obsolescence mitigation.

Supply support for 1N4460CUS/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 Corporation (now part of Microchip Technology) designs high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial markets, emphasizing radiation hardness, extended temperature operation, and military qualification.

The 1N4460CUS/TR belongs to Microsemi's MIL-PRF-19500/406-qualified Zener diode family, engineered specifically for voltage regulation in mission-critical systems where parameter stability, hermetic integrity, and long-term reliability are non-negotiable.

FAQ

What does the 'C' suffix in 1N4460CUS/TR indicate?

The 'C' suffix in 1N4460CUS/TR specifies ±2% Zener voltage tolerance at the 40 mA test current, distinguishing it from the standard ±5% version (1N4460US). This tighter tolerance is critical for precision reference applications where voltage accuracy directly impacts system measurement fidelity or control loop stability. The 1N4460CUS/TR maintains this specification across its full qualified temperature range and lifetime.

Is 1N4460CUS/TR RoHS compliant?

No, the 1N4460CUS/TR is not RoHS compliant because it uses tin/lead (Sn/Pb) terminations required for MIL-PRF-19500/406 qualification and hermetic reliability. RoHS-compliant versions (e3 suffix) are available only in commercial-grade variants (e.g., 1N4460CUS/TR-e3), which lack military screening and hermetic sealing. The 1N4460CUS/TR remains leaded to ensure solder joint integrity under thermal cycling and mechanical stress.

What is the maximum continuous Zener current for 1N4460CUS/TR?

The maximum continuous Zener current (I_ZM) for 1N4460CUS/TR is 230 mA at T_A = 25 °C, derived from its 1.5 W power rating and 6.2 V nominal Zener voltage (P = V × I). This value decreases with rising ambient temperature per the derating curve in Figure 2, reaching zero at approximately +150 °C case temperature. Exceeding I_ZM risks thermal runaway and permanent degradation.

How is polarity identified on the 1N4460CUS/TR package?

Polarity on the 1N4460CUS/TR is indicated by a single cathode band located near one end of the cylindrical MELF glass body. The banded end is the cathode and must be connected to the higher-potential node in the circuit; the unbanded end is the anode and connects to ground or the lower-potential rail. This marking is laser-etched or printed and remains visible after reflow soldering.

Can 1N4460CUS/TR be used in place of 1N4460US in existing designs?

Yes, the 1N4460CUS/TR is a direct functional replacement for 1N4460US in terms of package, pinout, and basic electrical behavior, but with improved ±2% voltage tolerance. No PCB changes are needed since both use the same A-size MELF (D-5A) footprint and cathode-band polarity marking. However, design validation should confirm that the tighter tolerance provides benefit without introducing unintended interaction in feedback networks.