Microchip Technology CDLL829/TR

Overview

CDLL829 from Central Semiconductor (CDI) is a temperature-compensated, hermetically sealed MELF (DO-213AA) Zener diode with nominal zener voltage 5.9–6.5 V, 7.5 mA test current, 15 Ω zener impedance, ±0.0005 %/°C temperature coefficient, and 500 mW power rating at +50°C - used for precision voltage reference in aerospace-grade power regulation circuits.

For engineers reviewing the CDLL829 datasheet, CDLL829 pinout, CDLL829 application, or CDLL829 equivalent, key selection criteria include its ultra-low tempco (0.0005 %/°C), tight V_Z tolerance band (5.9–6.5 V), DO-213AA glass MELF package, 2 µA reverse leakage at 3 V, and MIL-PRF-19500/159 qualification path via 1N829UR-1.

Technical Context

The CDLL829 employs metallurgically bonded, double-plug construction to achieve stable zener voltage over -65°C to +175°C operating range. Its temperature coefficient is specified as ±0.0005 %/°C across -55°C to +100°C, measured per JEDEC Std No.5, with zener impedance (Z_ZT) of 5 Ω derived using 10% 60 Hz AC superimposed on I_ZT.

This device operates in reverse-biased mode with cathode band positive, requires no heatsinking below +50°C, and follows strict derating (4 mW/°C above +50°C) to maintain 500 mW DC power dissipation limit. Reverse leakage remains ≤2 µA at 3 V_R and 25°C.

Key Specifications

Pinout & Package

Package: DO-213AA (MELF, SOD-80, LL34), hermetically sealed glass case with tin/lead lead finish. Axial mounting; polarity marked by cathode band (cathode end positive in operation).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL829, the 1N829UR-1 offers military-grade screening in a larger metal-can package, while CDLL829A shifts the optimal test current to 10 mA - both retain the same ultra-low tempco and voltage range but serve distinct reliability and bias-point design needs.

Availability

CDLL829 is available at Aetrix Electronics and suitable for aerospace power reference, satellite voltage monitor, and downhole instrumentation requiring stable component supply with full traceability and extended temperature performance.

Supply support for CDLL829 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

Central Semiconductor (CDI) is a U.S.-based manufacturer specializing in high-reliability discrete semiconductors, including Zener, Schottky, and switching diodes for defense, aerospace, and industrial markets.

The CDLL821–CDLL829A series was designed specifically for precision voltage reference applications demanding ultra-low temperature coefficients and hermetic packaging - targeting MIL-PRF-19500/159-compliant systems.

FAQ

What is the exact zener voltage range for CDLL829 at 7.5 mA test current?

The CDLL829 exhibits a zener voltage range of 5.9 V to 6.5 V when measured at I_ZT = 7.5 mA and 25°C. This range reflects manufacturing tolerance and is guaranteed per datasheet Table 1. The nominal value is often cited as 6.2 V, but design margins must accommodate the full 5.9–6.5 V span. CDLL829 maintains this specification across its qualified temperature range.

Does CDLL829 have a MIL-spec equivalent, and what is its part number?

Yes - the MIL-PRF-19500/159 qualified equivalent of CDLL829 is the 1N829UR-1, available in JAN, JANTX, JANTXV, and JANS levels. It shares identical electrical characteristics (V_Z, tempco, Z_ZT) but uses a hermetic TO-46 metal can package and undergoes military screening. CDLL829 itself is commercial-grade; the 1N829UR-1 is the direct MIL-spec counterpart.

What is the maximum power dissipation of CDLL829 at 100°C ambient?

At 100°C ambient, CDLL829's maximum power dissipation is 300 mW. This is calculated from its 500 mW rating at +50°C and 4 mW/°C derating: 500 mW − (100 − 50) × 4 mW = 300 mW. Operation above this limit risks thermal runaway or parametric shift. CDLL829 must be mounted on thermally appropriate substrates to maintain junction temperature within limits.

Is CDLL829 compatible with reflow soldering, and what is its peak temperature limit?

CDLL829 is rated for IR reflow per J-STD-020, with a peak temperature limit of 260°C for 10 seconds maximum. Its DO-213AA glass MELF package withstands standard lead-free reflow profiles, but thermal shock must be avoided due to coefficient-of-expansion mismatch with PCB materials. CDLL829 requires controlled ramp rates and no preheat exceeding 150°C to prevent glass fracture.

How does the temperature coefficient of CDLL829 compare to CDLL827A?

CDLL829 has a temperature coefficient of ±0.0005 %/°C, while CDLL827A is ±0.001 %/°C - CDLL829 offers half the drift per degree. Both operate in the same 5.9–6.5 V range, but CDLL829's tighter tempco results from refined double-plug construction and tighter process control. For applications requiring <±0.25 mV total drift over -55°C to +100°C, CDLL829 is the preferred choice over CDLL827A.