Diodes Incorporated DDZ31-7

Overview

DDZ31-7 from Diodes Incorporated is a surface-mount precision Zener diode with nominal zener voltage 31.0 V (min 30.32 V, max 31.88 V), 5 mA test current, 65 Ω zener impedance at 1 kHz, 0.05 µA reverse leakage at 25.0 V, and ±5% voltage tolerance. It operates in SOD123 package, delivers stable voltage reference in power supply feedback loops, and supports industrial sensor signal conditioning.

For engineers reviewing the DDZ31-7 datasheet, DDZ31-7 pinout, DDZ31-7 application, or DDZ31-7 equivalent, this page provides verified electrical parameters, thermal derating behavior, temperature coefficient data, packaging details, and automotive-grade alternatives for voltage regulation and reference design.

Technical Context

This Zener diode uses silicon planar epitaxial construction to achieve tight voltage tolerance and low dynamic impedance across its operating current range. Its 31 V breakdown point falls in the medium-voltage Zener region where temperature coefficient transitions from negative to positive, resulting in near-zero TC near 30–33 V - confirmed by Fig. 19 showing +0.04%/°C typical at 31 V.

The device is rated for 470 mW power dissipation at 25°C ambient on standard FR-4 PCB (2 oz copper, 1 in² pad), with thermal resistance of 266°C/W. Derating begins linearly above 75°C ambient per Figure 1, reaching zero power at 150°C junction temperature.

Key Specifications

Pinout & Package

DDZ31-7 is housed in the SOD123 plastic surface-mount package: 2.55–2.85 mm width (E), 1.40–1.70 mm length (D), 1.00–1.35 mm height (A), with cathode indicated by a visible band on the top surface. Terminals are matte tin-annealed alloy 42 leads, solderable per MIL-STD-202 Method 208.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DDZ31-7, BZX84-C30LT1G trades package size for higher impedance and reduced power handling, while DDZ30D-7 offers identical form factor and qualification but shifts regulation down by 0.5 V - making it suitable for fine-tuning existing 30 V designs without layout change.

Availability

DDZ31-7 is available at Aetrix Electronics and suitable for industrial power supplies, automotive body control modules, medical instrumentation, and test equipment calibration requiring stable component supply and long-term sourcing continuity.

Supply support for DDZ31-7 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 applications in cost-sensitive, high-volume systems - emphasizing tight V_Z tolerance, low Z_ZT, and automotive-grade reliability in compact SOD123 packaging.

FAQ

What is the maximum continuous reverse current for reliable operation?

DDZ31-7 is rated for 5 mA test current (I_ZT) and supports continuous reverse current up to 15 mA at 25°C ambient, limited by its 470 mW power rating. At 31 V, this corresponds to ~15.1 mA; operation beyond this requires thermal derating per Figure 1, especially above 75°C ambient.

Is DDZ31-7 qualified for automotive applications?

No - DDZ31-7 is the commercial-grade variant. The automotive-qualified version is DDZ31Q-7, which is AEC-Q101 certified, PPAP capable, and manufactured in IATF16949-certified facilities. DDZ31-7 lacks automotive change control and qualification documentation.

How does temperature affect its zener voltage stability?

At 31 V, DDZ31-7 exhibits a typical temperature coefficient of +0.04%/°C (Fig. 19), meaning voltage increases by ~12.4 mV per 10°C rise. This low, predictable drift enables stable reference performance across -65°C to +150°C without active compensation in most industrial applications.

Can it replace older 1N4748A Zener diodes?

Yes - DDZ31-7 matches the 1N4748A's 30 V nominal rating (1N4748A: 28.5–31.5 V) with tighter tolerance (±5% vs ±10%), lower Z_ZT (65 Ω vs 35 Ω), and SOD123 instead of DO-41. Layout adaptation is required, but electrical performance improves regulation accuracy and thermal efficiency.