Microchip Technology CDLL4122

Overview

CDLL4122 from Microsemi is a hermetically sealed, surface-mount silicon Zener diode in DO-213AA (MELF/LL34) package, rated for 36 V nominal Zener voltage at 250 µA test current, 200 Ω Zener impedance, and 27.38 V minimum Zener voltage at 11 mA maximum current - used for precision voltage reference and overvoltage protection in aerospace-grade power regulation circuits.

For engineers reviewing the CDLL4122 datasheet, CDLL4122 pinout, CDLL4122 application, or CDLL4122 equivalent, key selection factors include its ±5% Zener tolerance, -65°C to +175°C junction temperature range, 500 mW power dissipation at 125°C, low-leakage performance (<0.01 µA at 27.38 V), and MELF packaging optimized for high-reliability thermal cycling environments.

Technical Context

The CDLL4122 operates as a two-terminal voltage reference device with cathode-banded polarity, requiring reverse-bias connection to maintain stable Zener breakdown. Its metallurgically bonded construction ensures long-term parameter stability under thermal stress.

Designed for low-current regulation (250 µA test condition), it delivers predictable clamping behavior across its full operating current range (up to 11 mA), with Zener impedance measured using 25 µA AC superimposed on DC bias per MIL-PRF-19500/435.

Key Specifications

Pinout & Package

DO-213AA (MELF/LL34) hermetically sealed glass package with axial symmetry; no discrete pins - terminals are metallized end caps. Cathode identified by single black band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL4122, 1N4122UR-1 offers enhanced screening without electrical or mechanical change, while BZX84-C36 trades hermetic reliability and thermal capability for smaller size and lower cost in non-critical applications.

Availability

CDLL4122 is available at Aetrix Electronics and suitable for avionics power monitoring, satellite bus regulation, and downhole oilfield sensors requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for CDLL4122 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, radiation-hardened, and aerospace-grade components.

The CDLL series was developed for MIL-PRF-19500/435-compliant Zener reference applications demanding hermetic sealing, wide temperature operation, and long-term parametric stability in mission-critical systems.

FAQ

What is the Zener voltage tolerance for CDLL4122?

The CDLL4122 has a nominal Zener voltage of 36 V with a tolerance of ±5%, as specified in Note 1 of the official Microsemi datasheet. This tolerance applies when measured at 25°C ±3°C with the device in thermal equilibrium. The CDLL4122 does not carry a 'C' (±2%) or 'D' (±1%) suffix, so tighter tolerances are not applicable to this specific part number.

Is CDLL4122 suitable for surface-mount assembly?

Yes, CDLL4122 is designed for surface-mount assembly in its DO-213AA (MELF/LL34) package. It features a leadless, hermetically sealed glass construction with metallized end caps. Reflow profiles must respect its glass-body thermal limits, and board layout should accommodate its axial symmetry and coefficient of expansion matching guidance (6 ppm/°C).

What is the maximum reverse leakage current for CDLL4122?

The maximum reverse leakage current for CDLL4122 is 0.01 µA at a reverse voltage of 27.38 V, as specified in the Electrical Characteristics table. This ultra-low leakage supports use in battery-powered or energy-harvesting systems where standby current must be minimized without compromising voltage reference accuracy.

Does CDLL4122 require derating above 125°C ambient?

Yes, CDLL4122 requires linear power derating above 125°C case temperature (T_EC): 10 mW/°C reduction from the 500 mW maximum rating. At 150°C T_EC, its allowable power drops to 475 mW. This derating curve is defined in Figure 2 of the Microsemi datasheet and must be applied in thermal design for high-temperature deployments.

How is polarity identified on CDLL4122?

Polarity on CDLL4122 is identified by a single black band on the cathode end of the DO-213AA glass body. The device must be operated with the banded (cathode) end held at a more positive potential than the anode (unbanded end) to achieve Zener breakdown and voltage regulation. Reversing polarity subjects it to forward conduction, not regulation.