onsemi SZMM3Z3V9ST1G

Overview

SZMM3Z3V9ST1G from onsemi is a 3.89–4.16 V, 500 mW Zener voltage regulator diode in SOD−323 package, with 3.0 Ω dynamic impedance at 5 mA test current, −2.5 mV/°C temperature coefficient, and 450 pF capacitance at 0 V bias-used for precision low-voltage reference and overvoltage clamping in space-constrained portable power rails.

For engineers reviewing the SZMM3Z3V9ST1G datasheet, pinout, applications, or equivalent options, key selection criteria include Zener voltage tolerance (±3.2%), thermal resistance (250 °C/W with heatsink), ESD rating (>16 kV HBM), AEC−Q101 qualification, and SOD−323 mechanical compatibility with high-density PCB layouts.

Technical Context

This device operates as a two-terminal shunt regulator, maintaining stable reverse-biased breakdown voltage across its cathode-anode terminals under controlled current conditions. It delivers specified regulation within ±3.2% of nominal 3.975 V (midpoint of 3.89–4.16 V range) at I_ZT = 5 mA, with low dynamic impedance (≤90 Ω) ensuring minimal voltage deviation during transient load shifts.

Its −2.5 mV/°C temperature coefficient indicates predictable, linear V_Z drift over −65 to +150 °C junction range, enabling accurate compensation in temperature-sensitive references. The 450 pF junction capacitance at 0 V bias supports stable operation in low-frequency (<1 MHz) filtering and clamping roles without signal integrity degradation.

Key Specifications

Pinout & Package

SZMM3Z3V9ST1G uses the SOD−323 surface-mount package (1.7 mm × 1.25 mm × 0.9 mm), with cathode identified by a polarity band. The package supports reflow soldering up to 260°C for 10 seconds and meets UL 94 V−0 flammability rating.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX384-B3V9,115 and MMSZ4684T1G, SZMM3Z3V9ST1G offers superior voltage precision, automotive qualification, and verified ESD resilience-making it the preferred choice when system-level reliability and tight regulation are design-critical.

Availability

SZMM3Z3V9ST1G is available at Aetrix Electronics and suitable for automotive cabin controllers, USB power protection circuits, and wearable battery monitoring systems requiring stable component supply and long-term lifecycle support.

Supply support for SZMM3Z3V9ST1G 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

onsemi (Semiconductor Components Industries, LLC) is a global semiconductor supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

SZMM3Z3V9ST1G belongs to the MM3ZxxxST1G/SZMM3ZxxxST1G Zener regulator family-designed specifically for high-density, space-constrained applications demanding tight voltage tolerance, low profile, and automotive-grade reliability.

FAQ

What is the nominal Zener voltage of SZMM3Z3V9ST1G and how is it tested?

The nominal Zener voltage of SZMM3Z3V9ST1G is 3.975 V-the midpoint of its guaranteed range of 3.89 V to 4.16 V-measured at a test current (I_ZT) of 5.0 mA and ambient temperature of 25°C. This value is confirmed per onsemi's Electrical Characteristics table on page 3 of the official datasheet, and SZMM3Z3V9ST1G maintains this regulation within ±3.2% tolerance under defined thermal and current conditions.

Is SZMM3Z3V9ST1G qualified for automotive applications?

Yes, SZMM3Z3V9ST1G is AEC−Q101 qualified and PPAP capable, as explicitly stated in the "Specification Features" section of the onsemi datasheet. The "SZ" prefix denotes devices meeting automotive-specific site and control change requirements, and SZMM3Z3V9ST1G is validated for use in automotive cabin electronics, body control modules, and infotainment power supervision where reliability across extended temperature and vibration profiles is mandatory.

What is the maximum power dissipation of SZMM3Z3V9ST1G under standard PCB conditions?

SZMM3Z3V9ST1G has a steady-state power dissipation rating of 300 mW when mounted on a standard FR−4 board (single-sided copper, 1 cm² pad), with derating of 2.4 mW/°C above 25°C ambient. With an optimized heatsink (0.72 mm² pad on 38 mm² copper area), its rating increases to 500 mW, derated at 4.0 mW/°C-values confirmed in the "Maximum Ratings" table on page 2 of the onsemi datasheet.

Does SZMM3Z3V9ST1G have a specified temperature coefficient, and what does it mean for circuit design?

Yes, SZMM3Z3V9ST1G has a temperature coefficient of −2.5 mV/°C at I_ZT = 5 mA, meaning its Zener voltage decreases by 2.5 mV for every 1°C rise in junction temperature. This linear drift allows predictable compensation in reference circuits-e.g., in automotive applications spanning −40 to +105°C, total V_Z shift is ≈−363 mV, enabling firmware or analog correction to maintain system accuracy, as documented in the Electrical Characteristics table on page 3.

What packaging and marking information applies to SZMM3Z3V9ST1G?

SZMM3Z3V9ST1G is supplied in SOD−323 package (Case 477, Style 1), marked with "T7" on the cathode end, and packaged in tape-and-reel format (3,000 units per reel). The cathode is indicated by a polarity band, and the device carries a Pb−free indicator ("G") per onsemi's marking diagram on page 5 of the datasheet-consistent with RoHS, halogen-free, and BFR-free compliance requirements.