Microchip Technology CDLL4123

Overview

CDLL4123 from Microsemi is a hermetically sealed, surface-mount silicon Zener diode in DO-213AA (MELF/LL34) package, rated for 39 V nominal Zener voltage at 250 µA test current, 200 Ω maximum Zener impedance, and 9.8 mA maximum Zener current, used for precision voltage regulation in aerospace-grade power supply reference circuits.

For engineers reviewing the CDLL4123 datasheet, CDLL4123 pinout, CDLL4123 application, or CDLL4123 equivalent, this part supports low-current, high-stability voltage reference design in harsh-environment systems where junction temperature range (-65°C to +175°C), hermetic sealing, and ±5% Zener tolerance are critical selection criteria.

Technical Context

The CDLL4123 operates as a two-terminal, cathode-banded voltage reference device with metallurgically bonded construction and glass-encapsulated MELF packaging. Its thermal resistance is 100 °C/W (max) at L = 0 inch, and it exhibits 29.65 V minimum Zener voltage at 9.8 mA, confirming stable regulation under defined load conditions.

Designed per MIL-PRF-19500/435, the CDLL4123 supports operation up to +175°C junction temperature and requires matching of mounting surface coefficient of expansion (~6 ppm/°C) to minimize mechanical stress-induced parameter drift during thermal cycling.

Key Specifications

Pinout & Package

Package: DO-213AA (MELF/LL34), hermetically sealed glass case, axial leadless surface-mount configuration with cathode band marking.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL4123, 1N4123UR-1 offers identical regulation performance with enhanced process controls, while BZX84-C39 trades hermeticity and thermal range for compactness and cost-making CDLL4123 the sole choice for extended-temperature, mission-critical Zener reference needs.

Availability

CDLL4123 is available at Aetrix Electronics and suitable for aerospace power reference, downhole sensor biasing, military radio RF stage bias, and avionics display backlight control requiring stable component supply across extended temperature and lifecycle requirements.

Supply support for CDLL4123 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 defense, aerospace, and industrial markets.

The CDLL4123 belongs to Microsemi's legacy MIL-qualified Zener diode family designed specifically for precision voltage reference applications in extreme-environment electronics where hermeticity, wide temperature range, and long-term stability are mandatory.

FAQ

What is the Zener voltage tolerance for CDLL4123?

The CDLL4123 has a nominal Zener voltage of 39 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 ambient with the device in thermal equilibrium. No suffix indicates the standard ±5% grade; "C" or "D" suffixes would denote tighter ±2% or ±1% tolerances, which do not apply to the base CDLL4123 part number.

Is CDLL4123 suitable for surface-mount assembly?

Yes, CDLL4123 is explicitly designed for surface-mount use in its DO-213AA (MELF/LL34) package. The datasheet confirms "LEADLESS PACKAGE FOR SURFACE MOUNT" and provides dimensional data (D = 1.60–1.70 mm, G = 3.30–3.70 mm) compatible with standard MELF pick-and-place and reflow processes. Its axial symmetry and glass body require careful orientation control during placement due to the cathode band marking.

What is the maximum junction temperature rating for CDLL4123?

The CDLL4123 is rated for a junction and storage temperature range of -65°C to +175°C, as stated in the Maximum Ratings table. This specification enables operation in high-reliability applications such as avionics, downhole tools, and military electronics where sustained exposure to extreme thermal conditions is expected. Derating begins above +125°C case temperature at 10 mW/°C.

Does CDLL4123 have hermetic packaging?

Yes, CDLL4123 features a hermetically sealed glass case in the DO-213AA package, as confirmed by the "CASE: DO-213AA, Hermetically sealed glass case" designation in the Design Data section. This construction prevents moisture penetration and ensures long-term parametric stability in high-humidity or corrosive environments-critical for aerospace and defense applications.

What is the Zener test current for CDLL4123?

The CDLL4123 is characterized at a Zener test current (I_ZT) of 250 µA, as shown in the Electrical Characteristics table. This low test current enables stable regulation in ultra-low-power reference circuits without requiring additional current sources. The corresponding Zener voltage is 39 V nominal, with a minimum of 29.65 V guaranteed at the maximum Zener current (I_ZM) of 9.8 mA.