Diodes Incorporated BZT52C18Q-7-F

Overview

BZT52C18Q-7-F from Diodes Incorporated is an automotive-grade surface-mount Zener diode with a nominal zener voltage of 18 V, ±5.6% tolerance (16.8–19.1 V), 500 mW power dissipation at TL = +75°C, and 370 mW at TA = +25°C, used for precision voltage regulation and overvoltage protection in automotive control modules.

For engineers reviewing the BZT52C18Q-7-F datasheet, BZT52C18Q-7-F pinout, BZT52C18Q-7-F application, or BZT52C18Q-7-F equivalent, key selection criteria include zener voltage accuracy at 5 mA test current, low dynamic impedance (45 Ω at IZT), temperature coefficient (+12.6 mV/°C), and AEC-Q101 qualification for under-hood electronics.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable reference voltage across load variations and supply fluctuations. It features planar die construction and a cathode-band polarity indicator, optimized for automated SMT assembly on FR-4 PCBs with 1-inch copper pad layouts.

Thermal performance is defined by RθJA = 338 °C/W (on standard board) and RθJL = 150 °C/W, enabling reliable operation from –65 °C to +150 °C. Its low leakage (IR ≤ 0.1 µA at VR = 12.4 V) and tight voltage tolerance support robust voltage clamping in safety-critical automotive subsystems.

Key Specifications

Pinout & Package

Two-terminal device in SOD123 package: anode (unmarked end) and cathode (band-marked end). Mounting requires cathode-band alignment per PCB silkscreen; no internal circuitry or polarity inversion.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMSZ5245BQ-7-F and BZX84-C18-Q, BZT52C18Q-7-F delivers superior thermal robustness (370 mW vs. 350 mW), tighter voltage tolerance (±5.6% vs. ±6%), and lower impedance (45 Ω vs. 60 Ω), making it optimal for high-reliability automotive voltage references where long-term stability under thermal cycling is critical.

Availability

BZT52C18Q-7-F is available at Aetrix Electronics and suitable for automotive electronic control units, body control modules, and ADAS camera systems requiring stable component supply with guaranteed AEC-Q101 compliance and traceable lot-level documentation.

Supply support for BZT52C18Q-7-F 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, specializing in high-reliability components for automotive, industrial, and computing markets since 1959.

The BZT52C series belongs to Diodes' AEC-Q101-qualified Zener diode product line, engineered specifically for voltage regulation and transient suppression in harsh automotive environments including engine compartments and chassis electronics.

FAQ

What is the maximum reverse voltage (VR) at which BZT52C18Q-7-F guarantees IR ≤ 0.1 µA?

The datasheet specifies IR ≤ 0.1 µA at VR = 12.4 V. This value is derived from the "Maximum Reverse Current" column for BZT52C18 in the Electrical Characteristics table, where VR is defined as the voltage applied during leakage testing - not the zener voltage itself. It reflects the device's ability to block current below its breakdown threshold, critical for low-power standby circuits.

Can BZT52C18Q-7-F be used in parallel for higher power dissipation?

No - Zener diodes must not be paralleled due to mismatched breakdown voltages causing current hogging and thermal runaway. For higher power needs, use a single higher-rated device (e.g., PZMxx series) or implement active regulation with a pass transistor. The BZT52C18Q-7-F's 370 mW limit is absolute under standard PCB conditions.

Does the "Q" suffix indicate AEC-Q101 qualification for the entire reel or per-device level?

The "Q" suffix certifies that every unit on the reel has undergone full AEC-Q101 stress testing per the qualification sample plan (including HTOL, TCT, HAST, and ESD), not just representative samples. Lot traceability and test reports are provided with each shipment, meeting IATF 16949 requirements for PPAP submission.

How does the SOD123 package's RθJL = 150 °C/W impact thermal design in high-temperature environments?

With RθJL = 150 °C/W, a 370 mW dissipation raises junction temperature by 55.5 °C above lead temperature. In a +105 °C under-hood environment, TJ reaches 160.5 °C - exceeding the 150 °C max rating. Derating to ≤250 mW (or enhancing copper pour area) is required to maintain reliability at elevated ambient temperatures.