Nexperia USA Inc. BZX58550-B36X

Overview

BZX58550-B36X from Nexperia is a low-current Zener voltage regulator diode in SOD523 (SC-79) package, providing precise 36 V nominal regulation at 50 µA test current with ±2 % tolerance, 350 Ω typical differential resistance at 5 mA, and optimized leakage for noise-sensitive portable power rails.

For engineers reviewing the BZX58550-B36X datasheet, BZX58550-B36X pinout, BZX58550-B36X application, or BZX58550-B36X equivalent, this device is selected for ultra-low-bias voltage reference, battery-powered sensor biasing, and precision analog supply clamping where thermal stability and minimal board space are critical.

Technical Context

This Zener diode operates in reverse breakdown mode with a specified working voltage of 35.3 V to 36.7 V at I_Z = 50 µA, exhibiting a temperature coefficient of +0.05 mV/K and diode capacitance of 45 pF at 0 V and 1 MHz. Its low 50 µA test current enables stable regulation in micro-power circuits.

The device features intentional minor leakage current rise per AN90031 to improve switching speed and reduce noise in signal-path references. Thermal resistance from junction to ambient is 350 K/W on FR4 PCB with 35 mm² cathode copper area, supporting reliable operation up to 150 °C junction temperature.

Key Specifications

Pinout & Package

Package: SOD523 (SC-79), ultra-small surface-mount plastic package measuring 1.2 mm × 0.8 mm × 0.6 mm with flat leads and cathode marking bar.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX58550-C36, the BZX58550-B36X delivers tighter regulation and lower leakage for precision low-power use; versus MMSZ5245B, it trades off power capacity and dynamic impedance for 55% smaller footprint and superior micro-power performance.

Availability

BZX58550-B36X is available at Aetrix Electronics and suitable for portable sensor biasing, low-power microcontroller reset reference, and IoT transceiver supply clamping requiring stable component supply with guaranteed long-term sourcing.

Supply support for BZX58550-B36X 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 leading semiconductor manufacturer specializing in high-performance, energy-efficient logic, analog, and discrete components for automotive, industrial, and consumer markets.

The BZX58550 series belongs to Nexperia's low-current Zener regulator portfolio, engineered specifically for ultra-miniature, low-bias voltage reference applications in battery-constrained and noise-sensitive systems.

FAQ

What is the maximum reverse voltage the BZX58550-B36X can safely clamp without degradation?

The BZX58550-B36X has an absolute maximum non-repetitive peak reverse power dissipation of 40 W for 100 µs pulses at T_j = 25 °C. Its rated working voltage is 35.3–36.7 V at 50 µA, and it must not be subjected to sustained reverse voltages exceeding 36.7 V to avoid parametric shift or thermal runaway. Continuous operation above 300 mW total dissipation on standard FR4 will exceed its thermal limits.

Can the BZX58550-B36X replace a 1N4749A in a 36 V reference circuit?

No - the 1N4749A is a 1 W, DO-41 packaged Zener with 36 V nominal and ±5 % tolerance, requiring significantly higher bias current (typically 20–40 mA). The BZX58550-B36X is rated for 300 mW in SOD523 and specified at only 50 µA, making it unsuitable for high-current reference loads. Substitution would cause severe regulation loss unless the circuit is redesigned for microampere bias and thermal derating.

How does the "intentional minor rise of leakage current" benefit circuit performance?

Per AN90031, this controlled increase in reverse leakage improves carrier injection dynamics, reducing minority-carrier storage time and enabling faster turn-on during transient overvoltage events. In practice, this yields <10 ns response to ESD spikes and lowers broadband noise by 3–5 dB in audio and sensor front-ends compared to conventional low-leakage Zeners.

Is the SOD523 package compatible with standard reflow soldering profiles?

Yes - Nexperia specifies a standard lead-free reflow profile for SOD523, with peak temperature of 260 °C for ≤ 30 seconds and ramp rates compliant with IPC/JEDEC J-STD-020. The recommended footprint (Fig. 10) uses 0.5 mm pad width, 0.4 mm solder mask opening, and 2.15 mm center-to-center spacing to ensure coplanarity and void-free joints on fine-pitch PCBs.