Diodes Incorporated DDZ39F-7

Overview

DDZ39F-7 from Diodes Incorporated is a surface-mount precision Zener diode rated for 38.02–39.98 V nominal zener voltage at 5 mA test current, with 85 Ω maximum zener impedance at 5 mA and 0.05 µA maximum reverse leakage at 30 V. It operates across –65°C to +150°C and delivers stable voltage reference in low-power analog monitoring circuits.

For engineers reviewing the DDZ39F-7 datasheet, DDZ39F-7 pinout, DDZ39F-7 application, or DDZ39F-7 equivalent, this device serves as a tight-tolerance, low-capacitance (≈1.5 pF) voltage reference in power supply feedback loops, overvoltage protection clamps, and sensor biasing networks where thermal stability and SOD123 board-space efficiency are critical.

Technical Context

This Zener diode employs silicon planar construction with controlled avalanche breakdown to achieve precise, repeatable reverse-bias voltage regulation. Its 39 V nominal rating places it in the medium-voltage range where temperature coefficient crosses zero near room temperature - confirmed by Fig. 19 showing TC ≈ +0.04%/°C at 39 V.

Designed for DC voltage reference and clamping, it features low dynamic impedance (85 Ω @ 5 mA), minimal capacitance (1.5 pF typical), and robust thermal performance: R_θJA = 425 °C/W on minimal pad layout and 266 °C/W on 1-in² copper, enabling reliable operation in compact industrial PCBs.

Key Specifications

Pinout & Package

Package: SOD123 - surface-mount plastic package with cathode band marking; dimensions: 2.65 mm × 1.55 mm × 1.05 mm (L × W × H); moisture sensitivity level 1 per J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX84-C39LT1G and MMSZ4702T1G, DDZ39F-7 offers tighter voltage tolerance (±2.5% vs ±5%), lower leakage (0.05 µA vs 1 µA), and optimized thermal performance on minimal pads - making it preferred for space-constrained, high-accuracy industrial and automotive voltage reference designs.

Availability

DDZ39F-7 is available at Aetrix Electronics and suitable for industrial power supply feedback, automotive battery monitoring, medical sensor biasing, and test equipment reference applications requiring stable component supply and long-term manufacturability.

Supply support for DDZ39F-7 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, headquartered in Plano, Texas, with design, manufacturing, and sales operations across Asia, Europe, and North America.

The DDZ series targets precision voltage reference and clamping in space-constrained, thermally demanding environments - emphasizing tight V_Z tolerance, low leakage, and SOD123 compatibility for automotive, industrial, and medical end equipment.

FAQ

What is the maximum continuous power dissipation for DDZ39F-7 at 75°C ambient?

At T_L = +75°C, DDZ39F-7 supports 500 mW continuous power dissipation per the datasheet's Note 6. This rating assumes proper thermal coupling to a leadframe or PCB thermal pad, not free-air operation. Derating curves (Figure 1) confirm linear reduction to ~294 mW at 25°C with minimal copper area.

Does DDZ39F-7 have AEC-Q101 qualification?

No - DDZ39F-7 is the commercial-grade variant. The automotive-qualified version is DDZ39FQ-7, which carries AEC-Q101 qualification, PPAP capability, and is manufactured in IATF16949-certified facilities. The "Q" suffix denotes automotive compliance; DDZ39F-7 lacks this designation and associated change control documentation.

What is the typical junction-to-ambient thermal resistance on a standard FR-4 board?

When mounted on a single-sided FR-4 PCB (25 mm × 25 mm × 1.6 mm, 2 oz copper) with minimum recommended pad layout, R_θJA is 425 °C/W (Note 8). With a 1-in² copper pad, it improves to 266 °C/W (Note 7), directly impacting safe operating current limits under sustained load.

Can DDZ39F-7 be used in place of a 39 V Zener in legacy through-hole designs?

Yes, functionally - but only with PCB redesign. DDZ39F-7 uses the SOD123 surface-mount package (2.65 mm × 1.55 mm), not axial or DO-35. Direct replacement requires footprint conversion, rework of solder mask/paste stencil, and verification of thermal performance due to differing heat-spreading behavior versus through-hole equivalents.