Nexperia USA Inc. BZT52-C18X

Overview

BZT52-C18X from Nexperia is a ±5 % tolerance Zener diode in SOD123 package, rated for 18 V nominal Zener voltage at 5 mA test current, 170 Ω maximum differential resistance, and 590 mW total power dissipation at 25 °C ambient - used for precision voltage reference and low-power regulation in sensor biasing, ADC reference stabilization, and microcontroller reset circuitry.

For engineers reviewing the BZT52-C18X datasheet, BZT52-C18X pinout, BZT52-C18X application, or BZT52-C18X equivalent, key selection criteria include Zener voltage tolerance (±5 %), thermal resistance (210 K/W junction-to-solder-point), reverse current ≤0.05 μA at 14.4 V, temperature coefficient of +12.6 mV/K, and SOD123 footprint compatibility with automated SMT assembly.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable voltage across its terminals under varying load and supply conditions. Its 18 V nominal Zener voltage is specified at I_Z = 5 mA, with a typical temperature coefficient of +12.6 mV/K - indicating positive drift with rising junction temperature.

The device features low differential resistance (≤170 Ω) ensuring minimal output voltage variation under current changes, and is qualified for surface-mount use on FR4 PCBs with single-sided copper and tin-plated pads - supporting reliable thermal dissipation up to 590 mW at Tamb ≤ 25 °C.

Key Specifications

Pinout & Package

SOD123 plastic surface-mounted package: 2-terminal, flat lead, small outline; cathode marked by bar on body; dimensions: 3.75 mm × 1.7 mm × 1.3 mm (L × W × H); thermal pad for cathode supports 210 K/W junction-to-solder-point resistance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBZ5246BS and BZX84-C18, BZT52-C18X delivers 65 % higher power rating and 40 % lower thermal resistance in SOD123 - making it optimal for thermally demanding industrial regulation where long-term stability at full-rated current is required.

Availability

BZT52-C18X is available at Aetrix Electronics and suitable for industrial sensor biasing, microcontroller reset circuits, ADC reference stabilization, and low-power analog front-end designs requiring stable component supply with consistent parametric performance across production batches.

Supply support for BZT52-C18X 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

Nexperia is a global semiconductor expert focused on high-volume, high-reliability discrete and logic devices, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.

The BZT52 series targets general-purpose voltage regulation in cost-sensitive, space-constrained applications - delivering robust Zener performance in compact SMD packages without automotive qualification overhead.

FAQ

What is the maximum continuous reverse current the BZT52-C18X can sustain at 25 °C ambient?

The BZT52-C18X supports a maximum continuous reverse current of 250 mA, derived from its 590 mW power rating and 18 V Zener voltage (P = V × I → I = 590 mW / 18 V ≈ 32.8 mA), but absolute maximum rating allows 250 mA under short-duration pulse conditions. For continuous operation, design must limit average power to ≤590 mW using thermal derating curves - typically restricting I_Z to ≤30 mA at 25 °C ambient on standard FR4 PCB.

How does the +12.6 mV/K temperature coefficient affect regulation accuracy over −40 °C to +85 °C?

With a +12.6 mV/K coefficient, the Zener voltage shifts +1.575 V across a 125 K temperature span (85 − (−40)), resulting in a total drift of ~8.75 % relative to 18 V nominal. This means V_Z ranges from ~17.1 V at −40 °C to ~18.6 V at +85 °C at I_Z = 5 mA. Designers mitigate this by using temperature-compensated resistor dividers or selecting tighter-tolerance variants (e.g., B-series ±2 %) where drift budget is critical.

Can BZT52-C18X be used in forward conduction mode for ESD protection?

No - the BZT52-C18X is not characterized or rated for forward-biased ESD clamping. Its forward voltage is only specified ≤0.9 V at 10 mA (not at ESD-current levels), and its 250 mA absolute maximum forward current is insufficient for IEC 61000-4-2 Level 4 (30 A contact discharge). Dedicated TVS diodes like PESD5V0S1BA should be used instead; BZT52-C18X is intended strictly for reverse-bias voltage regulation.

What is the minimum reverse voltage required to achieve stable Zener breakdown behavior?

Stable Zener breakdown begins at approximately 90 % of nominal V_Z, so for BZT52-C18X, regulation initiates near 16.2 V. Below this, reverse current remains <0.05 μA (per datasheet Table 8), exhibiting high impedance. Full regulation with ≤170 Ω differential resistance is only guaranteed at V_R ≥ 16.8 V and I_Z ≥ 5 mA - meaning the device must be biased above 16.8 V with sufficient series resistance to sustain ≥5 mA for accurate voltage reference operation.