Microchip Technology CDLL4614

Overview

CDLL4614 from Microsemi is a hermetically sealed, glass-encapsulated 1.8 V Zener diode in DO-213AA (MELF/LL34) package, rated for 250 µA test current, 1200 Ω dynamic impedance, and 7.5 µA reverse leakage at 1 V, designed for precision low-current voltage reference and biasing in high-reliability aerospace and military circuits.

For engineers reviewing the CDLL4614 datasheet, CDLL4614 pinout, CDLL4614 application, or CDLL4614 equivalent, key selection criteria include its ±5% Zener tolerance, +175°C max operating temperature, 100 °C/W thermal resistance at L = 0 inch, and MIL-PRF-19500/435 qualification for space-grade analog signal conditioning.

Technical Context

The CDLL4614 operates as a two-terminal voltage reference device with cathode-banded polarity, requiring reverse-bias connection to maintain stable 1.8 V regulation. Its metallurgically bonded junction ensures long-term stability under thermal cycling between –65°C and +175°C.

Zener impedance of 1200 Ω is measured at 250 µA test current with 60 Hz AC superimposed at 10% IZT; maximum DC power dissipation is 500 mW at end-cap temperature (TEC) of +125°C, derating linearly at 10 mW/°C above that point.

Key Specifications

Pinout & Package

DO-213AA (MELF) glass package: cylindrical, leadless, surface-mountable with axial symmetry; cathode identified by single black band; no discrete pins - terminals are metallized end caps.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL4614, 1N4614UR-1 adds full military screening and traceability at higher cost, while CDLL4614C improves voltage tolerance at no change to thermal or reliability specs - enabling trade-offs between cost, certification, and precision.

Availability

CDLL4614 is available at Aetrix Electronics and suitable for avionics power sequencing, satellite sensor biasing, downhole telemetry calibration, and military radio frequency reference applications requiring stable component supply across extended temperature and radiation environments.

Supply support for CDLL4614 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) designs high-reliability analog and mixed-signal semiconductors for aerospace, defense, and industrial markets, emphasizing radiation tolerance, extended temperature operation, and military qualification.

The CDLL4614 belongs to Microsemi's MIL-PRF-19500/435-compliant Zener diode family, engineered specifically for precision voltage reference in mission-critical systems where long-term parametric stability and environmental survivability are non-negotiable.

FAQ

What is the Zener voltage tolerance of CDLL4614?

The CDLL4614 has a nominal Zener voltage of 1.8 V with a tolerance of ±5%, as specified in Note 1 of the manufacturer's datasheet. This tolerance applies under thermal equilibrium at 25°C ± 3°C and reflects the initial calibration spread before environmental stress. The CDLL4614 does not carry a "C" (±2%) or "D" (±1%) suffix, so tighter tolerances require selecting CDLL4614C or CDLL4614D variants instead of the base CDLL4614.

Is CDLL4614 suitable for surface-mount assembly?

Yes, CDLL4614 is packaged in DO-213AA (MELF/LL34), a leadless, cylindrical glass case explicitly designated for surface-mount applications. Its hermetic seal and axial symmetry allow reflow-compatible placement, though thermal expansion matching with the PCB substrate must be verified due to its +6 ppm/°C coefficient of expansion. The CDLL4614 does not require through-hole mounting and is commonly used in high-density SMT layouts for space-constrained avionics modules.

What is the maximum reverse leakage current for CDLL4614?

The maximum reverse leakage current (IR) for CDLL4614 is 7.5 µA at VR = 1 V, per the Electrical Characteristics table. This value is measured at 25°C and defines the upper bound of unwanted current flow when the diode is reverse-biased below its Zener knee. In low-power sensor bias networks, this leakage ensures minimal loading on high-impedance nodes - a key reason why CDLL4614 is selected over higher-leakage alternatives in precision analog designs.

Does CDLL4614 meet MIL-PRF-19500/435 requirements?

No, CDLL4614 itself is not MIL-PRF-19500/435 qualified. However, the functionally identical 1N4614UR-1 variant - listed alongside CDLL4614 in the same datasheet - is fully compliant with MIL-PRF-19500/435 for JAN, JANTX, JANTXV, and JANS levels. Engineers requiring formal military qualification must specify 1N4614UR-1 rather than CDLL4614, as the latter is a commercial-grade version sharing electrical specs but lacking screening and documentation traceability mandated by the specification.

What is the thermal resistance of CDLL4614 and how does it affect layout?

The CDLL4614 has a maximum thermal resistance (RθJL) of 100 °C/W at L = 0 inch, meaning junction-to-lead temperature rise is capped at 100°C per watt dissipated when leads are untrimmed. In practice, this requires careful PCB copper area allocation beneath the MELF body and attention to mounting surface COE matching (+6 ppm/°C) to avoid mechanical stress. For designs using CDLL4614 in 500 mW operation, thermal simulation must confirm junction temperature stays below +175°C - especially in enclosed, convection-limited enclosures where the CDLL4614's glass package offers no thermal pad path.