Diodes Incorporated BZT585B33TQ-7

Overview

BZT585B33TQ from Diodes Incorporated is a precision Zener diode with nominal 33 V breakdown voltage (±2.0% tolerance), 350 mW power dissipation, and SOD523 package. It operates across –65 °C to +150 °C, features 36.7 mV/°C temperature coefficient, and delivers stable voltage reference in automotive and industrial power regulation circuits.

For engineers reviewing the BZT585B33TQ datasheet, BZT585B33TQ pinout, BZT585B33TQ application, or BZT585B33TQ equivalent, key selection criteria include Zener voltage accuracy, thermal stability at elevated ambient temperatures, low reverse leakage (<0.05 µA @ 23.1 V), and AEC-Q101 qualification for automotive-grade reliability.

Technical Context

This Zener diode functions as a two-terminal voltage reference device, operating in reverse-biased breakdown mode with tightly controlled V_Z = 33 V (min 32.34 V, max 33.66 V) at I_ZT = 2 mA. Its ±2.0% tolerance and 36.7 mV/°C temperature coefficient enable predictable drift compensation in analog sensing and supply monitoring.

The device uses a planar-diffused silicon junction in a molded plastic SOD523 package with matte tin–annealed Alloy 42 leads. Thermal resistance R_θJA = 357 °C/W (FR-4 PCB, minimum pad layout) supports stable operation up to +150 °C junction temperature under defined derating conditions.

Key Specifications

Pinout & Package

Package: SOD523 - ultra-compact, low-profile surface-mount package (1.25 mm × 0.85 mm × 0.65 mm) with flat lead design optimized for thermal performance and board space efficiency.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5261BT1G and BZX84-C33, BZT585B33TQ offers tighter ±2.0% tolerance, AEC-Q101 qualification, and superior thermal performance in the smaller SOD523 footprint-making it optimal for space-constrained, high-reliability automotive voltage reference designs.

Availability

BZT585B33TQ is available at Aetrix Electronics and suitable for automotive power monitoring, industrial sensor reference supplies, LED driver overvoltage clamping, and PLC input protection requiring stable component supply and full traceability.

Supply support for BZT585B33TQ 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 BZT585B series belongs to Diodes' precision Zener diode product line, engineered specifically for automotive and industrial applications demanding tight voltage tolerance, high-temperature reliability, and AEC-Q101 compliance.

FAQ

What is the maximum reverse voltage that can be continuously applied to BZT585B33TQ without breakdown?

The rated Zener voltage is 33 V, but breakdown begins gradually above ~30 V. The absolute maximum reverse voltage before irreversible damage is not specified; however, sustained reverse bias must remain below the 33 V nominal value with appropriate current limiting to avoid exceeding 350 mW power dissipation. Derating is required above +25 °C ambient per Figure 1.

Is BZT585B33TQ suitable for use in a 12 V automotive system?

Yes - its 33 V Zener voltage provides ample margin above 12 V system transients (e.g., load dump up to 40 V). When used as a shunt clamp with proper series resistance, it reliably protects downstream circuitry from ISO 7637-2 Pulse 5a surges while maintaining low leakage (<0.05 µA) during normal 12–14 V operation.

How does the SOD523 package affect thermal performance compared to SOD-123?

The SOD523 has higher thermal resistance (R_θJA = 357 °C/W) than SOD-123 (~250 °C/W), limiting its usable power at elevated temperatures. However, its smaller footprint (1.25 × 0.85 mm vs. 2.9 × 1.3 mm) enables denser layouts, and its flat-lead design improves solder joint reliability and reduces mechanical stress in vibration-prone automotive environments.

Does BZT585B33TQ require external current limiting in all applications?

Yes - as a two-terminal Zener, it must always be used with a series current-limiting resistor to prevent thermal runaway. For example, at 33 V Zener voltage and 2 mA test current, a 3.3 kΩ resistor is required from a 40 V rail. The resistor value must be recalculated based on worst-case supply voltage, desired Zener current, and power dissipation limits of both resistor and diode.