Diodes Incorporated DDZ28-7

Overview

DDZ28-7 from Diodes Incorporated is a surface-mount precision Zener diode with nominal zener voltage 27.7–29.13 V, ±5% tolerance at I_ZT = 5 mA, 55 Ω dynamic impedance at test current, and 23.0 V reverse breakdown threshold. It operates as a voltage reference or overvoltage clamp in power supply feedback loops, analog sensor biasing, and industrial voltage monitoring circuits.

For engineers reviewing the DDZ28-7 datasheet, DDZ28-7 pinout, DDZ28-7 application, or DDZ28-7 equivalent, key selection criteria include zener voltage tolerance (±5%), low thermal resistance (425 °C/W on minimal pad), automotive-grade qualification eligibility (Q-suffix variant), and SOD123 package compatibility with high-density PCB layouts.

Technical Context

This device functions as a two-terminal, silicon-based voltage reference diode operating in reverse-biased breakdown mode. Its zener voltage is stabilized by avalanche multiplication above ~6.8 V, confirmed by temperature coefficient data showing +0.07%/°C typical for the 27–30 V range (Fig. 18).

It delivers stable regulation under pulsed conditions (short-duration test per Note 9), supports 0.05 µA maximum reverse leakage at 23.0 V, and maintains 55 Ω impedance at 5 mA test current - critical for low-noise reference stability in analog front-ends and feedback networks.

Key Specifications

Pinout & Package

DDZ28-7 uses the SOD123 surface-mount plastic package with cathode indicated by a band on the top surface. The device has two terminals: anode and cathode - no internal connections beyond the PN junction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with DDZ28-7, BZX84-C27LT1G offers identical voltage tolerance but inferior dynamic regulation due to higher impedance, while MMSZ5256ET1G matches the SOD123 form factor and improves regulation performance but requires verification of thermal dissipation in constrained layouts.

Availability

DDZ28-7 is available at Aetrix Electronics and suitable for industrial power supplies, automotive sensor interfaces, programmable logic controller I/O protection, and portable test equipment requiring stable component supply and long-term obsolescence management.

Supply support for DDZ28-7 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 the Americas.

The DDZ series targets precision voltage reference and clamping applications in industrial, automotive, and consumer systems where tight V_Z tolerance, low leakage, and green packaging are mandatory.

FAQ

What is the maximum continuous reverse current the DDZ28-7 can sustain without degradation?

The DDZ28-7 is rated for 5 mA zener test current (I_ZT) and supports continuous operation up to its 294 mW power limit at +25°C ambient on minimal pad layout. At that condition, sustained current must remain ≤10.5 mA (294 mW ÷ 28 V), but long-term reliability is optimized below 5 mA to minimize thermal stress and parameter drift.

Does DDZ28-7 have automotive qualification, and what does that entail?

The DDZ28-7 itself is the commercial-grade part; its automotive-qualified counterpart is DDZ28Q-7. That variant is AEC-Q101 qualified, manufactured in IATF16949-certified facilities, and PPAP-capable - meaning it undergoes stress testing for temperature cycling, humidity, and mechanical shock specific to automotive under-hood environments.

How does the SOD123 package affect thermal performance compared to larger packages like DO-35?

The SOD123 package has higher thermal resistance (425 °C/W vs. ~200 °C/W for DO-35) due to smaller copper pad area and shorter leadframe path. This means DDZ28-7 reaches higher junction temperatures at the same power dissipation, requiring explicit PCB copper pour design or derating to 294 mW instead of the 500 mW rating achievable with improved heatsinking.

Can DDZ28-7 replace older Zener diodes like 1N4749A in existing designs?

Yes - DDZ28-7 matches the 28 V nominal voltage and ±5% tolerance of 1N4749A, but in SOD123 instead of DO-41. Electrical performance is comparable (55 Ω vs. 35 Ω Z_ZT), though the smaller package requires updated stencil and reflow profiles. No circuit modification is needed if layout accommodates the 2.65 mm × 1.55 mm footprint.