Microchip Technology CDLL4623

Overview

CDLL4623 from Microsemi is a hermetically sealed, glass-encapsulated MELF (DO-213AA) Zener diode with nominal 4.3 V zener voltage, 250 µA test current, 1600 Ω zener impedance at I_ZT, 4.0 µA max reverse leakage at 2 V, and 77 mA maximum DC zener current. It operates across –65°C to +175°C and is used for precision voltage reference and low-current regulation in aerospace power conditioning circuits.

For engineers reviewing the CDLL4623 datasheet, CDLL4623 pinout, CDLL4623 application, or CDLL4623 equivalent, key selection considerations include its ±5% zener tolerance, 500 mW power rating at T_EC = +125°C, axial thermal expansion coefficient of +6 ppm/°C, hermetic glass package suitability for high-reliability environments, and MIL-PRF-19500/435 compliance for space-grade designs.

Technical Context

The CDLL4623 functions as a low-noise, temperature-stable voltage reference in series-shunt regulator topologies, leveraging metallurgical bonding and hermetic glass sealing to ensure long-term parametric stability under thermal cycling and radiation exposure. Its 4.3 V nominal zener voltage is specified at 250 µA test current with 1600 Ω dynamic impedance, supporting stable operation in low-power bias networks.

Designed for high-reliability applications, the device exhibits a maximum reverse leakage of 4.0 µA at 2 V and forward voltage ≤1.1 V at 200 mA. Its thermal resistance of 100 °C/W (L = 0 inch) and Z_JX of 35 °C/W enable predictable junction-to-case thermal behavior in constrained mounting configurations.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4623UR-1, the CDLL4623 offers identical performance in non-military programs but lacks formal QPL listing; compared with CDLL4622, it provides higher reference voltage for improved noise immunity in noisy 5 V domains, at the cost of reduced headroom.

Availability

CDLL4623 is available at Aetrix Electronics and suitable for aerospace power reference, satellite sensor biasing, downhole instrumentation, and military radio RF stage bias requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CDLL4623 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 CDLL4614–CDLL4627 series was developed to deliver MIL-qualified, hermetic Zener references with stable low-current regulation for mission-critical voltage referencing in extreme environments.

FAQ

What is the zener voltage tolerance for CDLL4623?

The CDLL4623 has a nominal zener voltage of 4.3 V with a tolerance of ±5%, as defined in Note 1 of the datasheet. This tolerance applies under thermal equilibrium at 25°C ±3°C. No "C" (±2%) or "D" (±1%) suffix is present in the CDLL4623 designation, confirming the ±5% grade. The CDLL4623 maintains this specification across its full operating temperature range when used within rated power limits.

Is CDLL4623 suitable for surface-mount assembly?

Yes, CDLL4623 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 per J-STD-020 guidelines. The axial symmetry and absence of leads eliminate tombstoning risk, making CDLL4623 compatible with standard SMT pick-and-place and reflow processes used in high-reliability PCB assembly.

What is the maximum power dissipation for CDLL4623 at +150°C end-cap temperature?

At T_EC = +150°C, CDLL4623 power dissipation is derated linearly from 500 mW at +125°C using the specified 10 mW/°C slope. This yields 500 mW – (25°C × 10 mW/°C) = 250 mW maximum. The device remains within safe operating limits up to +175°C, where dissipation reaches zero. Thermal impedance data (Z_JX = 35 °C/W) supports junction temperature modeling under actual board-level cooling conditions.

Does CDLL4623 have a specified forward voltage?

Yes, CDLL4623 specifies a maximum forward voltage of 1.1 V at 200 mA forward current, per the "Maximum Ratings" table. This value characterizes the diode's anode-to-cathode drop during forward conduction and is relevant for applications involving dual-mode operation (e.g., ESD protection clamping). The forward voltage is measured under pulsed conditions to avoid self-heating effects and reflects typical silicon PN junction behavior at high current density.

How does the axial coefficient of expansion affect CDLL4623 mounting?

The CDLL4623 has an axial coefficient of expansion (COE) of approximately +6 ppm/°C. To minimize thermomechanical stress during thermal cycling, the mounting surface-such as ceramic substrate or metal-core PCB-should match this COE closely. Mismatches exceeding ±2 ppm/°C may accelerate hermetic seal fatigue or glass-body microfracture over repeated temperature excursions, especially in aerospace or downhole applications where reliability exceeds 10 years.