Microchip Technology CDLL825/TR

Overview

CDLL825/TR from Central Semiconductor (CDI) is a hermetically sealed, surface-mount temperature-compensated Zener diode in DO-213AA (MELF/LL34) package, rated for 5.9–6.5 V zener voltage at 7.5 mA test current, 15 Ω zener impedance, ±0.002 %/°C temperature coefficient, and 500 mW power dissipation at +50°C. It serves as a precision voltage reference in analog power supply feedback loops.

For engineers reviewing the CDLL825/TR datasheet, CDLL825/TR pinout, CDLL825/TR application, or CDLL825/TR equivalent, key selection criteria include low TC (0.002 %/°C), stable zener impedance under load, MELF package thermal robustness, and operation across –65°C to +175°C ambient range.

Technical Context

The CDLL825/TR uses metallurgically bonded double-plug construction to achieve tight voltage tolerance and low temperature drift. Its zener impedance of 19 Ω is measured with 10% 60 Hz AC superimposed on 7.5 mA DC test current per JEDEC 5, ensuring stability under dynamic load conditions.

Designed for high-reliability analog references, it maintains voltage stability within ±96 mV over –55°C to +100°C, with reverse leakage limited to 2 µA at 3 V and 25°C. The DO-213AA glass package provides hermetic sealing and axial CTE (~6 ppm/°C) for matched thermal expansion on PCBs.

Key Specifications

Pinout & Package

Package: DO-213AA (MELF/LL34), hermetically sealed glass case with tin/lead lead finish; cathode identified by band; axial CTE ≈ +6 ppm/°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with CDLL825/TR, CDLL825A/TR offers lower impedance for improved transient response, while 1N825UR-1 delivers identical performance with full MIL-spec qualification-neither is pin-compatible in the sense of drop-in replacement without documentation review, but both share identical footprint and biasing.

Availability

CDLL825/TR is available at Aetrix Electronics and suitable for switch-mode power supply feedback, industrial sensor signal conditioning, and high-temperature automotive control unit applications requiring stable component supply and long-term parametric consistency.

Supply support for CDLL825/TR 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 Corp. (CDI) is a U.S.-based manufacturer specializing in high-reliability discrete semiconductors, including Zener, Schottky, and switching diodes, with emphasis on ruggedized and temperature-stable devices.

The CDLL82x series was developed to deliver MIL-grade voltage reference stability in commercial-form-factor MELF packages, targeting analog power and sensing applications where IC-based references lack thermal or radiation resilience.

FAQ

What is the zener voltage tolerance of CDLL825/TR?

The CDLL825/TR has a specified zener voltage range of 5.9 V to 6.5 V at 7.5 mA test current (I_ZT). This ±5% nominal spread reflects manufacturing tolerance under JEDEC-standard test conditions and is verified per batch data sheets. The CDLL825/TR achieves tighter effective regulation in-circuit due to its low 19 Ω zener impedance and ultra-low temperature coefficient.

Does CDLL825/TR require heatsinking in standard PCB layouts?

No, CDLL825/TR does not require external heatsinking in standard FR-4 layouts operating below 500 mW dissipation. Its DO-213AA glass package dissipates heat axially, and the 4 mW/°C derating above +50°C allows full-rated power up to +50°C ambient. At +100°C ambient, maximum dissipation drops to 300 mW - still sufficient for typical reference current loads (<10 mA).

Is CDLL825/TR compatible with lead-free reflow processes?

CDLL825/TR features tin/lead lead finish and is rated for wave soldering and hand-soldering per J-STD-001. It is not qualified for Pb-free reflow profiles (e.g., JEDEC J-STD-020 Level 3 peak of 260°C); exposure to such temperatures risks glass-to-metal seal integrity. For lead-free assembly, consult Central Semiconductor's CDLL825-TR-LF variant or equivalent qualified MELF Zeners.

How does the temperature coefficient of CDLL825/TR compare to CDLL827/TR?

CDLL825/TR has a temperature coefficient of ±0.002 %/°C, while CDLL827/TR is tighter at ±0.001 %/°C. Both share identical V_Z range (5.9–6.5 V) and DO-213AA package, but CDLL827/TR achieves lower drift via optimized doping and junction design - making it preferred for metrology-grade references where <±50 mV total drift over –55°C to +100°C is required. CDLL825/TR remains optimal for cost-sensitive industrial applications.

Can CDLL825/TR be used in bidirectional configurations?

No - CDLL825/TR is a unidirectional Zener diode intended for reverse-bias operation only, with cathode marked by a band. Unlike the †-marked CDLL822 and CDLL824 (which are double-anode types), CDLL825/TR lacks symmetrical breakdown characteristics and must be oriented with banded (cathode) end positive relative to anode. Reverse polarity application may cause irreversible damage.