Microchip Technology CDLL4108

Overview

CDLL4108 from Microsemi is a hermetically sealed, surface-mount silicon Zener diode in DO-213AA (MELF/LL34) package, rated for 14 V nominal Zener voltage at 250 µA test current, 200 Ω maximum Zener impedance, 0.05 µA maximum reverse leakage at 10.65 V, and 27 mA maximum Zener current. It operates across –65°C to +175°C junction temperature and delivers stable voltage reference in precision analog power rails.

For engineers reviewing the CDLL4108 datasheet, CDLL4108 pinout, CDLL4108 application, or CDLL4108 equivalent, key selection criteria include its ±5% Zener tolerance, low-leakage performance at 10.65 V reverse bias, thermal resistance of 100 °C/W, and suitability for high-reliability aerospace, industrial control, and test equipment where hermetic sealing and wide temperature operation are required.

Technical Context

The CDLL4108 functions as a two-terminal voltage reference device with cathode-banded polarity, requiring operation with the banded end positive. Its Zener impedance is measured using a 60 Hz RMS AC signal equal to 10% of I_ZT (25 µA), per Note 2 in the specification table.

Thermal design must account for axial coefficient of expansion (~+6 ppm/°C) to match mounting surface COE. Power derating begins at +125°C ambient (TEC), decreasing by 10 mW/°C above that point, with maximum DC dissipation of 500 mW at TEC = +125°C.

Key Specifications

Pinout & Package

DO-213AA (MELF) package: cylindrical, leadless, hermetically sealed glass body with metallurgically bonded ends. Cathode identified by single dark band. No PCB leads - soldered directly via end caps.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4108UR-1, CDLL4108 lacks MIL qualification but offers identical electrical behavior and hermetic reliability at lower cost; versus BZX84-C14, CDLL4108 provides extended temperature capability and superior long-term stability due to glass-sealed construction.

Availability

CDLL4108 is available at Aetrix Electronics and suitable for avionics power monitoring, industrial PLC analog input protection, and downhole oilfield instrumentation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CDLL4108 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, RF, and timing solutions for aerospace, defense, and industrial markets.

The CDLL series was designed specifically for high-stability, hermetically sealed Zener reference applications demanding extended temperature operation, low leakage, and long-term parametric consistency in mission-critical systems.

FAQ

What is the Zener voltage tolerance for CDLL4108?

The CDLL4108 has a nominal Zener voltage of 14 V with a tolerance of ±5%, as specified in Note 1 of the manufacturer's datasheet. This tolerance applies when measured at 25°C ±3°C with the device in thermal equilibrium. The CDLL4108 does not carry a "C" (±2%) or "D" (±1%) suffix, so tighter tolerance variants are not applicable to this specific part number.

Does CDLL4108 require heatsinking in typical applications?

No, CDLL4108 does not require external heatsinking in standard applications. With a maximum DC power dissipation of 500 mW at TEC = +125°C and thermal resistance of 100 °C/W, it remains within safe junction limits at ≤27 mA under moderate ambient conditions. The CDLL4108's DO-213AA package relies on end-cap conduction into the PCB, and typical layouts with ≥10 mm² copper pad per end suffice for most uses.

Can CDLL4108 be used in place of CDLL4107 or CDLL4109?

CDLL4108 is not a direct replacement for CDLL4107 (13 V) or CDLL4109 (15 V), as each part has a distinct nominal Zener voltage and corresponding reverse breakdown threshold. While all share identical package, test current, and impedance specs, substituting CDLL4108 alters the regulated voltage level by ±1 V - potentially violating system-level accuracy or safety margins. Always verify target voltage requirements before selecting among CDLL4107/CDLL4108/CDLL4109.

What is the meaning of "TEC" in CDLL4108 derating curves?

"TEC" stands for "end cap temperature", defined as the temperature measured at the metallized end cap of the DO-213AA package. It is the reference point for the CDLL4108's power derating curve: DC power dissipation must be reduced by 10 mW per °C above TEC = +125°C. This differs from case or ambient temperature and reflects localized thermal conditions critical to CDLL4108's reliability in high-density layouts.

Is CDLL4108 RoHS compliant?

The CDLL4108 features a tin/lead lead finish, as stated in the design data section, and therefore is not RoHS compliant. It is intended for applications where legacy Pb-based solder compatibility or high-reliability hermetic sealing outweighs RoHS requirements - such as aerospace, defense, and certain industrial systems. For RoHS-compliant alternatives, consult Microchip's current-generation Zener offerings with matte tin terminations.