Diodes Incorporated MMSZ5251BS-7-F

Overview

MMSZ5251BS-7-F from Diodes Incorporated is a surface-mount Zener diode with a nominal zener voltage of 22 V, ±5% tolerance (20.9–23.1 V), rated power dissipation of 200 mW, and maximum zener impedance of 29 Ω at 5.6 mA test current. It features SOD-323 package, cathode band polarity marking, and is used for precision voltage regulation and overvoltage protection in low-power analog circuits.

For engineers reviewing the MMSZ5251BS-7-F datasheet, MMSZ5251BS-7-F pinout, MMSZ5251BS-7-F application, or MMSZ5251BS-7-F equivalent, key selection considerations include zener voltage accuracy at 5.6 mA, thermal resistance (625 °C/W), reverse leakage (<0.1 µA at 17 V), and compatibility with automated SMT assembly on FR-4 PCBs.

Technical Context

This Zener diode operates in reverse breakdown mode to maintain stable reference voltage under varying load and temperature conditions. Its planar die construction ensures consistent breakdown characteristics, while the SOD-323 package enables high-density placement and reliable thermal performance up to +150 °C junction temperature.

The device exhibits low dynamic impedance (29 Ω at I_ZT = 5.6 mA) and minimal reverse leakage (≤0.1 µA at V_R = 17 V), supporting accurate voltage clamping in feedback networks and sensor biasing applications where stability and low quiescent current are critical.

Key Specifications

Pinout & Package

Package: SOD-323 - ultra-small plastic surface-mount case (2.3–2.7 mm length × 1.2–1.4 mm width × 0.25–0.35 mm height), cathode indicated by band marking, compatible with reflow soldering per J-STD-020D Level 1 moisture sensitivity.

Key Features

Applications

Availability

MMSZ5251BS-7-F is available at Aetrix Electronics and suitable for industrial sensor signal conditioning, USB-C power delivery reference clamp, and low-power IoT node voltage monitor requiring stable component supply with full traceability and long-term lifecycle support.

Supply support for MMSZ5251BS-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, with design and manufacturing operations across Asia and the Americas.

The MMSZ52xxBS series belongs to Diodes' general-purpose Zener diode product line, engineered specifically for cost-sensitive, space-constrained voltage regulation and protection in consumer, industrial, and computing applications.

FAQ

What is the maximum reverse voltage this diode can withstand before breakdown?

The MMSZ5251BS-7-F has a nominal zener voltage of 22 V with a guaranteed range of 20.9 V to 23.1 V at 5.6 mA test current. Below 20.9 V, it remains in high-impedance reverse blocking state with leakage ≤0.1 µA at 17 V; breakdown begins gradually near the lower limit and stabilizes within the specified range.

Can this Zener diode be used in series for higher voltage references?

Yes - multiple MMSZ5251BS-7-F diodes may be connected in series to achieve higher reference voltages (e.g., two in series yield ~44 V), but tolerance stacking and thermal tracking must be considered; total zener impedance becomes additive, and power derating must follow the 200 mW per device limit.

Is the SOD-323 package compatible with standard reflow profiles?

Yes - the SOD-323 package is qualified for lead-free reflow per J-STD-020D Level 1 moisture sensitivity, with peak temperatures up to 260 °C. Recommended pad layout (AP02001) and thermal relief design ensure void-free solder joints and mechanical reliability on FR-4 boards.

How does its zener impedance affect regulation accuracy under load?

With Z_ZT = 29 Ω at 5.6 mA, a 1 mA load change causes ~29 mV output shift - acceptable for non-critical biasing. For tighter regulation, pair with a low-output-impedance buffer or use higher-test-current Zeners (e.g., MMSZ5252BS at 5.2 mA) with lower Z_ZT.