Microchip Technology CDLL4128

Overview

CDLL4128 from Microsemi is a hermetically sealed, surface-mount silicon Zener diode in DO-213AA (MELF/LL34) package, rated for 60 V nominal Zener voltage at 250 µA test current, 400 Ω Zener impedance, 45.6 V minimum Zener voltage at 6.4 mA maximum current, and operating junction temperature range of –65°C to +175°C - used in precision voltage reference and overvoltage protection circuits.

For engineers reviewing the CDLL4128 datasheet, CDLL4128 pinout, CDLL4128 application, or CDLL4128 equivalent, key selection factors include its ±5% Zener tolerance, low-leakage performance (≤0.01 µA at 45.6 V), thermal resistance of 100 °C/W, hermetic glass construction, and suitability for high-reliability aerospace and industrial power regulation.

Technical Context

The CDLL4128 operates as a two-terminal voltage-reference device with cathode-banded polarity, requiring reverse-bias connection. Its Zener breakdown mechanism delivers stable regulation under low-current conditions (250 µA I_ZT) and supports up to 6.4 mA I_ZM without exceeding 500 mW dissipation at T_EC = +125°C.

Thermal design relies on matching the device's axial coefficient of expansion (+6 ppm/°C) to the PCB substrate; its DO-213AA package enables automated placement while maintaining hermeticity and long-term parameter stability across military-grade temperature extremes.

Key Specifications

Pinout & Package

DO-213AA (MELF) hermetic glass package: cylindrical, leadless, metallurgically bonded, cathode identified by single black band. Dimensions: D = 1.60–1.70 mm diameter, G = 3.30–3.70 mm length, F = 0.41–0.55 mm band width.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 1N4128UR-1 and BZX84-C62, the CDLL4128 uniquely combines MELF SMT compatibility, hermetic reliability, and full military-temperature operation - making it irreplaceable in new high-reliability embedded designs where board space, long-term stability, and extreme environment resilience are non-negotiable.

Availability

CDLL4128 is available at Aetrix Electronics and suitable for avionics power monitoring, downhole sensor biasing, spacecraft EPS reference, and military radio RF stage protection requiring stable component supply across extended temperature and long-lifecycle programs.

Supply support for CDLL4128 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, mixed-signal, and radiation-hardened components for aerospace, defense, and industrial markets.

The CDLL4128 belongs to Microsemi's legacy CDLL series of hermetic Zener diodes, engineered specifically for precision voltage reference and overvoltage protection in mission-critical systems where parameter stability under thermal, mechanical, and radiation stress is essential.

FAQ

What is the Zener voltage tolerance for CDLL4128?

The CDLL4128 has a nominal Zener voltage of 60 V with a standard tolerance of ±5%, as defined in Note 1 of the datasheet. This tolerance applies when measured at 25°C ±3°C with the device in thermal equilibrium. No "C" (±2%) or "D" (±1%) suffix is present in the CDLL4128 marking, confirming the ±5% grade.

Is CDLL4128 suitable for surface-mount assembly?

Yes, CDLL4128 is designed for surface-mount assembly in its DO-213AA (MELF/LL34) package. It features a leadless, hermetically sealed glass body with standardized dimensions (D = 1.60–1.70 mm, G = 3.30–3.70 mm) compatible with automated pick-and-place and reflow processes per J-STD-020.

What is the maximum reverse leakage current for CDLL4128?

The maximum reverse leakage current for CDLL4128 is 0.01 µA at a reverse voltage of 45.6 V, as specified in the Electrical Characteristics table. This ultra-low leakage supports energy-efficient biasing in battery-operated and low-power monitoring systems where standby current must be minimized.

Does CDLL4128 meet any military specifications?

CDLL4128 is part of the CDLL4099–CDLL4135 family covered under MIL-PRF-19500/435 via its counterpart 1N4099UR-1 through 1N4135UR-1 series. While CDLL4128 itself is the commercial/hermetic variant, its electrical and environmental specifications align with JAN/JANTX-level requirements including temperature range, hermeticity, and test methodology.

What is the thermal resistance of CDLL4128?

The junction-to-case thermal resistance (R_θJC) of CDLL4128 is 100 °C/W maximum at L = 0 inch, as stated in the Design Data section. This value is critical for calculating junction temperature rise under power dissipation and informs heatsinking or board copper area requirements in high-temperature deployments.