Diodes Incorporated BZT585B18TQ-7

Overview

BZT585B18TQ from Diodes Incorporated is a precision Zener diode with 18 V nominal breakdown voltage (±2.0% tolerance), 350 mW power dissipation, and SOD523 package. It operates across –65 °C to +150 °C, features 45 Ω dynamic impedance at 5 mA test current, and delivers stable voltage reference in low-power analog circuits and automotive sensor signal conditioning.

For engineers reviewing the BZT585B18TQ datasheet, BZT585B18TQ pinout, BZT585B18TQ application, or BZT585B18TQ equivalent, key selection criteria include Zener voltage accuracy, thermal stability (16.9 mV/°C tempco), low reverse leakage (<0.05 µA at 12.6 V), and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This Zener diode uses silicon planar epitaxial construction to achieve tight 2.0% V_Z tolerance and low temperature coefficient (16.9 mV/°C) at 5 mA. Its SOD523 package enables high power density (350 mW) in a 1.25 mm × 0.85 mm footprint with flat-lead design for improved thermal conduction.

The device exhibits 80 pF capacitance at 0 V and 1 MHz, 0.9 V forward voltage at 10 mA, and maintains <0.05 µA reverse current up to 12.6 V - making it suitable for precision biasing and overvoltage clamping where low parasitic capacitance and minimal leakage are critical.

Key Specifications

Pinout & Package

Package: SOD523 - ultra-compact surface-mount plastic package (1.25 mm × 0.85 mm × 0.65 mm), flat-lead design optimized for low profile and thermal performance on FR-4 PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5245B-TP and BZX84-C18, BZT585B18TQ offers tighter voltage tolerance, automotive qualification, and superior thermal performance in a smaller SOD523 footprint - making it optimal for space-constrained, safety-critical designs requiring long-term stability.

Availability

BZT585B18TQ is available at Aetrix Electronics and suitable for automotive cabin electronics, industrial PLC analog inputs, medical infusion pump power monitors, and EV battery management systems requiring stable component supply with full traceability and lifecycle support.

Supply support for BZT585B18TQ 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 BZT585 series belongs to Diodes' precision Zener diode product line, engineered specifically for automotive and industrial applications demanding high accuracy, AEC-Q101 qualification, and robust thermal performance in miniature packages.

FAQ

What is the maximum reverse voltage before breakdown for BZT585B18TQ?

The BZT585B18TQ has a nominal Zener voltage of 18.0 V with ±2.0% tolerance, meaning breakdown occurs between 17.64 V and 18.36 V at I_ZT = 5 mA. At 12.6 V (70% of nominal), reverse current is guaranteed ≤0.05 µA - confirming stable non-conduction below the specified knee voltage.

Is BZT585B18TQ compatible with lead-free reflow profiles?

Yes - BZT585B18TQ uses matte tin annealed terminals over Alloy 42 leadframe and is rated for peak reflow temperatures up to 260 °C per JEDEC J-STD-020. Its moisture sensitivity level is Grade 1, eliminating bake requirements prior to assembly.

How does the temperature coefficient affect regulation accuracy over temperature?

With a +16.9 mV/°C temperature coefficient at 5 mA, BZT585B18TQ's Zener voltage increases by approximately 1.7 V across a 100 °C range (–40 °C to +60 °C). This predictable positive drift enables first-order compensation in reference circuits using matched NTC thermistors or complementary transistor pairs.

Can BZT585B18TQ replace older BZX84-C18 in existing designs?

No direct drop-in replacement - BZT585B18TQ uses SOD523 (1.25 mm × 0.85 mm), while BZX84-C18 uses SOT-23 (3.0 mm × 1.4 mm) with three terminals. The cathode-anode polarity matches, but PCB layout, thermal relief, and reflow profile must be requalified due to differences in package size, power rating, and qualification status.