Microchip Technology CDLL4100

Overview

CDLL4100 from Microsemi is a hermetically sealed, surface-mount silicon Zener diode in DO-213AA (MELF/LL34) package, rated for 7.5 V nominal Zener voltage at 250 µA test current, 200 Ω Zener impedance, and 51 mA maximum Zener current - used for precision voltage regulation and reference in aerospace-grade power supply monitoring circuits.

For engineers reviewing the CDLL4100 datasheet, CDLL4100 pinout, CDLL4100 application, or CDLL4100 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 (10 µA @ 5.7 V), and MELF packaging optimized for high-reliability thermal cycling environments.

Technical Context

The CDLL4100 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 maintains tight dynamic impedance (200 Ω) across operating temperature.

Designed for hermetic reliability, it features metallurgically bonded construction, 100 °C/W junction-to-case thermal resistance at L = 0 inch, and axial coefficient of expansion (~6 ppm/°C) matched to ceramic or Kovar mounting surfaces - critical for MIL-PRF-19500/435-compliant avionics and space-qualified systems.

Key Specifications

Pinout & Package

DO-213AA (MELF) hermetically sealed glass package: cylindrical body, no external leads; cathode identified by single dark band; mounted axially on PCB with end-cap contact.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL4100, 1N4100UR-1 offers identical electrical specs with enhanced reliability screening, while BZX84-C7V5 trades hermetic performance for compact size and lower cost - making CDLL4100 the optimal choice for mission-critical thermal and radiation resilience.

Availability

CDLL4100 is available at Aetrix Electronics and suitable for aerospace power monitoring, satellite bus regulation, avionics sensor biasing, and tactical radio RF clamping requiring stable component supply across extended temperature and radiation-exposed environments.

Supply support for CDLL4100 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 CDLL4100 belongs to Microsemi's legacy MIL-PRF-19500/435-qualified Zener diode family, engineered specifically for voltage reference stability under extreme thermal cycling, radiation exposure, and long-term hermetic integrity requirements.

FAQ

What is the Zener voltage tolerance for CDLL4100?

The CDLL4100 has a nominal Zener voltage of 7.5 V with a tolerance of ±5%, measured at 250 µA test current and 25°C ambient. This tolerance is specified per Note 1 in the official Microsemi datasheet and applies to all standard CDLL4100 units without C (±2%) or D (±1%) suffixes. The CDLL4100 is not rated for tighter tolerances unless specially ordered with suffix coding.

Does CDLL4100 require heatsinking in typical applications?

No, CDLL4100 does not require external heatsinking in standard operation. With a maximum power dissipation of 500 mW at 125°C case temperature and 100 °C/W junction-to-case thermal resistance, it remains within safe limits at ≤51 mA Zener current (7.5 V × 51 mA ≈ 383 mW). The CDLL4100 relies on PCB copper area and axial mounting for thermal transfer, consistent with DO-213AA design guidelines.

Is CDLL4100 compatible with lead-free reflow processes?

The CDLL4100 features a tin/lead lead finish and is not qualified for Pb-free reflow profiles. Its glass-body construction and metallurgical bond are optimized for SnPb eutectic soldering (peak ~220°C). Using CDLL4100 in lead-free reflow (≥260°C peak) risks thermal shock cracking or seal degradation. For RoHS-compliant designs, consider alternative MELF Zeners explicitly rated for lead-free assembly, not the CDLL4100.

What is the maximum reverse voltage that can be applied to CDLL4100 before breakdown?

The CDLL4100 begins controlled Zener breakdown at its nominal 7.5 V rating, with regulation maintained up to its maximum Zener current of 51 mA. Its absolute maximum reverse voltage is defined by the 5.70 V parameter - the maximum reverse voltage at which leakage remains ≤10 µA. Exceeding 5.70 V initiates measurable conduction; sustained operation above 7.5 V at >51 mA exceeds power rating and risks thermal runaway. The CDLL4100 must be operated within its specified Zener region, not as a general-purpose rectifier.

Can CDLL4100 be used in series or parallel configurations for higher voltage or current capability?

CDLL4100 is not recommended for parallel operation due to mismatched Zener impedances causing current imbalance and thermal instability. Series connection is possible for higher reference voltages (e.g., two CDLL4100s yield ~15 V), but requires individual current limiting resistors and accounts for tolerance stacking (±10% total). The CDLL4100 datasheet does not specify matched pairs or series-derating guidance, so such configurations require empirical validation per application. Standard use is single-device, reverse-biased operation.