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onsemi MMSZ5257ET1G
- Part No.:
- MMSZ5257ET1G
- Manufacturer:
- onsemi
- Category:
- Single Zener Diodes
- Package:
- SOD-123
- Datasheet:
-
MMSZ5257ET1G.pdf
- Description:
- DIODE ZENER 33V 500MW SOD123
- Quantity:
- Payment:
- Shipping:
Inventory:12,316
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Product details
Overview
MMSZ5257ET1G from onsemi is a 33 V ±5% Zener voltage regulator diode in SOD-123 surface-mount package, rated for 500 mW power dissipation at 75 °C on FR-5 board, with 700 Ω maximum dynamic impedance at 3.8 mA test current and 0.1 µA reverse leakage at 25 V, used for precision voltage reference and overvoltage protection in power supply rails.
For engineers reviewing the MMSZ5257ET1G datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, thermal derating behavior, cathode/anode terminal mapping, and direct alternatives for voltage-clamping and biasing circuits requiring stable 33 V regulation under medium-current conditions.
Technical Context
This Zener diode operates in reverse breakdown to maintain a stable 33 V reference across its terminals when biased above its knee current (IZK = 3.8 mA), with temperature coefficient optimized for minimal drift across −55 °C to +150 °C junction range. Its 700 Ω dynamic impedance at IZT ensures predictable regulation under small-signal AC perturbations.
The device uses a planar-diffused silicon junction in a void-free thermosetting plastic SOD-123 case, rated for 225 W nonrepetitive surge (8 × 20 µs) and ESD robustness >16 kV HBM. Thermal resistance from junction-to-lead is 150 °C/W, enabling efficient heat transfer to PCB copper in high-density layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 31.35–34.65 V at 3.8 mA - defines clamping threshold for overvoltage protection and reference accuracy |
| Power Dissipation (PD) | 500 mW @ TL = 75 °C - sets maximum continuous DC power handling on standard FR-5 board |
| Zener Impedance (ZZT) | 700 Ω max @ IZT = 3.8 mA - determines AC regulation stability under signal ripple or transient load changes |
| Reverse Leakage (IR) | 0.1 µA max @ VR = 25 V - ensures low standby current in high-impedance bias networks |
| Thermal Resistance (RJL) | 150 °C/W - quantifies junction-to-lead heat transfer efficiency for thermal design margining |
| ESD Rating | Class 3 (>16 kV HBM) - supports robust handling in automated assembly and end-use environments |
| Surge Power (Ppk) | 225 W @ 8 × 20 µs - enables transient suppression of short-duration voltage spikes without failure |
Pinout & Package
Package: SOD-123 (1.60 × 2.69 × 1.16 mm), surface-mount, cathode indicated by polarity band. Void-free thermosetting plastic case with UL 94 V-0 flammability rating and Pb-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (Banded End) | Cathode | Connected to regulated output or higher-potential node; reverse-biased during Zener operation |
| 2 (Non-banded End) | Anode | Connected to ground or lower-potential reference; completes bias path for reverse conduction |
Key Features
| Feature | Design Value |
|---|---|
| 500 mW power rating on FR-5 board | Supports sustained voltage regulation in compact power management circuits without forced cooling |
| ±5% Zener voltage tolerance | Enables predictable clamping within 1.65 V margin at 33 V nominal, suitable for mid-precision references |
| 150 °C maximum junction temperature | Allows operation in automotive under-hood and industrial control environments with ambient up to 125 °C |
| 225 W peak surge capability | Withstands IEC 61000-4-5 level 4 surges without degradation in transient protection applications |
| Pb-free SOD-123 package | Complies with RoHS and J-STD-020 reflow profiles, supporting lead-free manufacturing processes |
Applications
| Industrial Power Supply Monitoring | Automotive ECU Reference Clamp |
|---|---|
Use Scenario: Monitoring 36 V battery rail in PLC I/O modules to detect overvoltage faults before damage occurs. IC Role / Device Role / Timing Role: Zener clamp limiting input to downstream LDO or supervisor IC. Use Value: Maintains 33 V regulation with <0.1 µA leakage at 25 V, minimizing quiescent current in always-on monitoring circuits. |
Use Scenario: Protecting microcontroller ADC reference input from load-dump transients in 12 V/24 V dual-voltage ECUs. IC Role / Device Role / Timing Role: Fast-acting shunt regulator absorbing surge energy above 33 V threshold. Use Value: Withstands 225 W 8 × 20 µs pulses per ISO 7637-2, preserving ADC accuracy during cranking events. |
| Medical Sensor Bias Network | IoT Node Voltage Reference |
Use Scenario: Providing stable bias voltage for analog front-end amplifiers in portable ECG sensors. IC Role / Device Role / Timing Role: Precision DC reference source with low thermal drift across body-temperature range. Use Value: Temperature coefficient optimized for <±0.02 %/°C drift near 33 V, ensuring <0.5% reference error from 0–50 °C. |
Use Scenario: Setting reference point for Li-ion battery fuel gauge ICs in smart home sensors. IC Role / Device Role / Timing Role: Low-leakage Zener establishing accurate 33 V threshold for charge-state detection. Use Value: 0.1 µA leakage at 25 V prevents measurable battery drain over multi-year deployments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| BZX84-C33 | 33 V ±5%, SOT-23 package, 300 mW rating, 60 Ω ZZT @ 5 mA | Lower power and smaller footprint; higher ZZT limits AC regulation fidelity | Select for space-constrained designs where 300 mW suffices and tighter impedance is not required |
| 1N4745A | 33 V ±5%, DO-41 through-hole, 1 W rating, 35 Ω ZZT @ 38 mA | Higher power and lower impedance but requires through-hole assembly and larger board area | Select for legacy through-hole production or high-current biasing where 1 W dissipation is needed |
Compared with MMSZ5257ET1G, BZX84-C33 offers smaller size but reduced power and higher impedance, while 1N4745A provides superior regulation and thermal capacity at the cost of mounting flexibility and modern compliance.
Availability
MMSZ5257ET1G is available at Aetrix Electronics and suitable for industrial power monitoring, automotive ECU protection, and medical sensor biasing requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for MMSZ5257ET1G 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 is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and IoT markets.
The MMSZ5257ET1G belongs to the MMSZ52xxET1G Zener regulator series designed for high-reliability, surface-mount voltage reference and clamping in space-constrained, medium-power applications.
FAQ
What is the nominal Zener voltage and tolerance of the MMSZ5257ET1G?
The MMSZ5257ET1G has a nominal Zener voltage of 33 V with a standard tolerance of ±5%, meaning the actual measured voltage falls between 31.35 V and 34.65 V when tested at 3.8 mA and thermal equilibrium at 30 °C. This tolerance is confirmed in the Electrical Characteristics table on page 3 of the official onsemi datasheet.
What is the maximum power dissipation rating for the MMSZ5257ET1G under typical PCB conditions?
The MMSZ5257ET1G is rated for 500 mW total power dissipation on an FR-5 board at a lead temperature (TL) of 75 °C, with linear derating of 6.7 mW/°C above that temperature. This rating assumes use of the minimum recommended footprint per onsemi's mechanical guidelines.
Does the MMSZ5257ET1G meet automotive qualification standards?
The MMSZ5257ET1G itself is not AEC-Q101 qualified; however, the SZMMSZ5257ET1G variant (with SZ prefix) is explicitly stated as AEC-Q101 qualified and PPAP capable. Engineers requiring automotive-grade reliability must specify the SZ-prefixed version, not the standard MMSZ5257ET1G.
What is the reverse leakage current specification for the MMSZ5257ET1G at 25 V?
The MMSZ5257ET1G exhibits a maximum reverse leakage current (IR) of 0.1 µA when subjected to 25 V reverse bias at 25 °C ambient, as specified in the Electrical Characteristics table. This low leakage supports ultra-low-power biasing in battery-operated systems.
How is the cathode identified on the MMSZ5257ET1G SOD-123 package?
The cathode of the MMSZ5257ET1G is marked by a polarity band on the SOD-123 case - the banded end corresponds to Pin 1 (cathode), while the non-banded end is the anode (Pin 2). This marking aligns with JEDEC-standard SOD-123 orientation and is visible under standard optical inspection.
MMSZ5257ET1G Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- MMSZ52xxxT1G
- Package/Case:
- SOD-123
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 500 mW
- Impedance (Max) (Zzt):
- 58 Ohms
- Current - Reverse Leakage @ Vr:
- 100 nA @ 25 V
- Voltage - Forward (Vf) (Max) @ If:
- 900 mV @ 10 mA
- Operating Temperature:
- -55°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOD-123
MMSZ5257ET1G FAQ
1.How can I place an order for MMSZ5257ET1G through Aetrix?
Please submit a Request for Quotation (RFQ) for MMSZ5257ET1G on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for MMSZ5257ET1G reliable?
The price and inventory of MMSZ5257ET1G are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MMSZ5257ET1G is usually 5 days.
3.What payment methods are accepted for MMSZ5257ET1G?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MMSZ5257ET1G transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MMSZ5257ET1G?
MMSZ5257ET1G orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MMSZ5257ET1G order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for MMSZ5257ET1G?
For technical support, including MMSZ5257ET1G datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MMSZ5257ET1G requirements.
6.How does Aetrix verify that MMSZ5257ET1G is sourced from the original manufacturer or authorized distributors?
All MMSZ5257ET1G products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that MMSZ5257ET1G meets industry standards.
7.What is the process for return or replacement of MMSZ5257ET1G?
All MMSZ5257ET1G units undergo pre-shipment inspection (PSI). If there is an issue with MMSZ5257ET1G, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The MMSZ5257ET1G part is unused and in its original packaging.
Return procedure for MMSZ5257ET1G:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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