Diodes Incorporated MMBZ5258BT-7-F

Overview

MMBZ5258BT-7-F from Diodes Incorporated is a 36 V, 150 mW surface-mount Zener diode in SOT-523 package, with nominal zener voltage 36 V (min 34.2 V, max 37.8 V), test current 3.4 mA, and zener impedance 70 Ω at 1 kHz; used for precision voltage regulation and overvoltage protection in low-power sensor interfaces and portable battery management circuits.

For engineers reviewing the MMBZ5258BT-7-F datasheet, MMBZ5258BT-7-F pinout, MMBZ5258BT-7-F application, or MMBZ5258BT-7-F equivalent, key selection criteria include zener voltage tolerance, dynamic impedance at specified test current, power derating above 25°C, reverse leakage at rated voltage, and SOT-523 thermal resistance (833 °C/W) for PCB layout validation.

Technical Context

This device operates as a silicon planar Zener diode optimized for stable reverse-bias breakdown at 36 V under DC or low-frequency transient conditions. It exhibits 0.1 μA maximum reverse leakage at 27 V and 70 Ω dynamic impedance measured at 1 kHz and 3.4 mA test current.

The SOT-523 package enables high-density placement on compact PCBs, with thermal resistance of 833 °C/W limiting continuous power dissipation to 150 mW at 25°C ambient and requiring linear derating above that temperature per Figure 1.

Key Specifications

Pinout & Package

SOT-523 ultra-small plastic surface-mount package with three terminals: anode, cathode, and case (non-connected). Cathode identified by marking band; polarity confirmed per top-view schematic in DS30267 Rev. 11-2.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BZX584-C36 and MM3Z36VT1G, MMBZ5258BT-7-F offers the smallest footprint (SOT-523) and lowest leakage (0.1 μA), making it optimal for ultra-compact, low-quiescent-current designs where 150 mW power limit is sufficient.

Availability

MMBZ5258BT-7-F is available at Aetrix Electronics and suitable for portable battery monitoring, industrial sensor signal conditioning, USB-C power delivery clamp, and automotive cabin control interface requiring stable component supply and RoHS-compliant sourcing.

Supply support for MMBZ5258BT-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, headquartered in Plano, Texas, serving industrial, computing, consumer, and communications markets with high-reliability components.

This part belongs to the MMBZ52xxBT series of general-purpose Zener diodes designed specifically for space-constrained, low-power voltage regulation and protection in surface-mount applications.

FAQ

What is the maximum reverse leakage current for MMBZ5258BT-7-F?

The maximum reverse leakage current is 0.1 μA at 27 V, measured at 25°C ambient temperature. This value ensures minimal parasitic loading on high-impedance circuits such as sensor outputs or microcontroller ADC references, preserving measurement accuracy and battery life in always-on devices.

Can MMBZ5258BT-7-F be used in place of a 33 V Zener diode?

No - MMBZ5258BT-7-F is specified for 36 V nominal breakdown (34.2–37.8 V range), not 33 V. Substituting it for a 33 V Zener would raise the clamping voltage by ~3 V, risking overvoltage exposure to downstream components. Use MMBZ5257BT-7-F (33 V) instead for that requirement.

Is the SOT-523 package compatible with standard reflow profiles?

Yes - the SOT-523 package supports standard lead-free reflow profiles per J-STD-020D Level 1 moisture sensitivity. Its molded plastic case meets UL 94V-0 flammability rating, and matte tin plating ensures reliable solder wetting without voiding or dewetting under typical peak temperatures of 260°C.

How does thermal derating affect continuous operation?

Power dissipation must be linearly derated above 25°C ambient at 1.2 mW/°C (150 mW ÷ 833 °C/W). At 85°C ambient, maximum allowable power drops to 78 mW. Designers must verify PCB copper area and airflow to maintain junction temperature below 150°C under worst-case load and ambient conditions.