Microchip Technology CDLL4622

Overview

CDLL4622 from Microsemi is a hermetically sealed, glass-encapsulated MELF (DO-213AA) Zener diode with nominal 3.9 V zener voltage, 250 µA test current, 1650 Ω maximum zener impedance at I_ZT, 5.0 µA maximum reverse leakage at 2 V, and 80 mA maximum DC zener current. It operates from –65°C to +175°C and is used for precision voltage reference and low-current regulation in high-reliability aerospace and military power supplies.

For engineers reviewing the CDLL4622 datasheet, CDLL4622 pinout, CDLL4622 application, or CDLL4622 equivalent, key selection criteria include its ±5% zener tolerance, hermetic DO-213AA package, 500 mW power rating at 125°C end-cap temperature, low-leakage performance at 2 V reverse bias, and compatibility with MIL-PRF-19500/435 screening levels.

Technical Context

The CDLL4622 functions as a low-current, high-stability voltage reference diode optimized for operation at 250 µA test current. Its metallurgically bonded junction ensures long-term stability under thermal cycling, and its hermetic glass package provides immunity to moisture and contaminants critical for space-grade applications.

Designed per MIL-PRF-19500/435, the CDLL4622 supports JAN, JANTX, JANTXV, and JANS screening levels. Its axial coefficient of expansion (+6 ppm/°C) requires matched PCB substrate selection to minimize mechanical stress during thermal excursions.

Key Specifications

Pinout & Package

Package: DO-213AA (MELF, SOD-80, LL34), hermetically sealed glass case with tin/lead lead finish. Axial device with cathode band marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL4622, 1N4622UR-1 adds formal military qualification and traceability for defense programs, while CDLL4622C improves initial tolerance and dynamic impedance for metrology-grade references-neither is pin-compatible by default, but both share identical DO-213AA mechanical footprint and polarity marking.

Availability

CDLL4622 is available at Aetrix Electronics and suitable for aerospace power reference, military sensor biasing, downhole instrumentation, and avionics thermal monitoring requiring stable component supply across extended temperature ranges and long-lifecycle programs.

Supply support for CDLL4622 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, mixed-signal, and RF solutions for aerospace, defense, and industrial markets.

The CDLL4622 belongs to Microsemi's legacy MIL-PRF-19500/435-compliant Zener diode family, engineered for extreme-environment voltage reference and regulation in mission-critical systems.

FAQ

What is the zener voltage tolerance for CDLL4622?

The CDLL4622 has a nominal zener voltage of 3.9 V with a tolerance of ±5%, as specified in Note 1 of the manufacturer's datasheet. This tolerance applies at 25°C ambient temperature with the device junction in thermal equilibrium. Tighter tolerances are available via suffix variants: CDLL4622C offers ±2%, and CDLL4622D offers ±1%.

Is CDLL4622 suitable for surface-mount assembly?

Yes, CDLL4622 uses the DO-213AA (MELF) package, which is a leadless cylindrical surface-mount format also known as SOD-80 or LL34. Its glass body and metallized ends support reflow soldering, though thermal profile must respect the 175°C maximum junction temperature and avoid thermal shock during ramp-up.

What is the maximum power dissipation for CDLL4622 at 150°C end-cap temperature?

Per the power derating curve (Figure 2), CDLL4622 is rated for 500 mW at T_EC = +125°C, with linear derating of 10 mW/°C above that point. At 150°C end-cap temperature, maximum power dissipation is 250 mW (500 mW – 10 mW/°C × 25°C). Exceeding this risks thermal runaway or parameter shift.

Does CDLL4622 have a defined cathode marking, and how is polarity identified?

Yes, CDLL4622 features a visible cathode band on the glass body - the banded end is the cathode and must be held at the more positive potential during Zener operation. Polarity is unambiguous and consistent across all DO-213AA devices in the CDLL4614–CDLL4627 series, as confirmed in the "POLARITY" section of the design data.

Can CDLL4622 replace CDLL4621 in an existing design?

CDLL4622 (3.9 V) can replace CDLL4621 (3.6 V) only if the circuit accommodates the +0.3 V increase in reference voltage and associated changes in bias current and regulation error. Both share identical package, test current (250 µA), and thermal specs, but the zener voltage difference may affect loop stability or accuracy in feedback-sensitive applications.