Alternatives to onsemi MMSZ5242B
onsemi MMSZ5242B and its qualified second sources, compared on form/fit/function, stock, lifecycle and price — the same checks Parter runs inside a BOM.
 MMSZ5242Bonsemi |  MMSZ5242BT1Gonsemi |  MMSZ5242B-7-FDiodes Incorporated | +1more | |
|---|---|---|---|---|
| FFF Compatibility | The pinout is identical (Pin 1 Cathode, Pin 2 Anode), but the package is SOD-123 instead of the original flat-lead SOD-123F. They share compatible PCB footprints, but the package name and lead form differ.The SOD-123 has gull-wing leads, whereas the original SOD-123F package uses flat/folded leads, resulting in a slightly higher package profile (approx 1.16mm vs 0.75mm for flat lead).Matches all critical electrical parameters including 12V nominal Zener voltage, 500mW maximum power rating, 5% voltage tolerance, and identical leakage current specs (1µA at 9.1V). | The pin assignments are identical (Pin 1 Cathode, Pin 2 Anode), but the package is SOD-123 instead of SOD-123F. They are footprint-compatible on standard land patterns.SOD-123 utilizes gull-wing leads compared to the flat-lead style of SOD-123F, altering the physical profile height.Matches the 12V nominal breakdown voltage, 500mW power dissipation, and 5% tolerance criteria perfectly. | ||
 AI Summary | MMSZ5242B by onsemi: Zener Diode 12 V 500 mW ±5% Surface Mount SOD-123. | This is an active, highly reliable industry-standard alternative from onsemi that matches the electrical performance of the obsolete Taiwan Semi part. It uses a standard SOD-123 package which fits on the same land pattern as the original flat-lead SOD-123F package. Automotive-grade options (SZMMSZ-prefix) are also available in this series.
| An active, widely available alternative from Diodes Inc. that provides matching electrical ratings and reliability. It mounts on the existing footprint but introduces standard gull-wing leads (SOD-123) instead of flat-lead (SOD-123F).
| |
| Lifecycle Status | Obsolete | Active | Active | |
| Market Availability | Non-stock | In stock | In stock | |
| REACH | REACH | REACH | REACH | |
| RoHS | RoHS | RoHS | RoHS | |
| Description | Zener Diode 12 V 500 mW ±5% Surface Mount SOD-123 | Zener Diode 12 V 500 mW ±5% Surface Mount SOD-123 | Zener Diode 12 V 500 mW ±5% Surface Mount SOD-123 | |
| Manufacturer | onsemi | onsemi | Diodes Incorporated | |
| Type | Diodes | Diodes | Diodes | |
| Datasheet | Open | Open | Open | |
| Lead Time | 11 weeks | 44 weeks | 40 weeks | |
| Country of Origin | JP | - | - | |
| Export Control Class Number | EAR99 | EAR99 | EAR99 | |
| HTSUS Code | 8541.10.0050 | - | - | |
| Moisture Sensitivity Level | 1 (Unlimited) | - | - | |
| Tolerance | ±5% | - | - | |
| Power - Max | 500.0mW | - | - | |
| Mounting Type | Surface Mount | - | - | |
| Package / Case | SOD-123F | - | - | |
| Impedance (Max) (Zzt) | 30.0Ω | - | - | |
| Supplier Device Package | SOD-123F | - | - | |
| Voltage - Zener (Nom) (Vz) | 12.0V | - | - | |
| Current - Reverse Leakage @ Vr | 1 µA @ 9.1 V | - | - |
Unlock all 3 alternatives
- Find & compare verified second sources
- Spot risk early with real-time part monitoring
- Stay compliant and production-ready
Related parts
| Part | Market availability | Lifecycle | Alternatives available |
|---|---|---|---|
 MMSZ5226Bonsemi | Discontinued | Obsolete | 5Alternatives availableSee Alternatives |
| MMSZ5245Bonsemi | In stock | Obsolete | 5Alternatives availableSee Alternatives |
| MMSZ5239Bonsemi | In stock | Obsolete | 6Alternatives availableSee Alternatives |
 MMSZ4680T1onsemi | Discontinued | Obsolete | 5Alternatives availableSee Alternatives |
| MMSZ4686T1onsemi | Discontinued | Obsolete | 6Alternatives availableSee Alternatives |
| MMSZ4697T1onsemi | Discontinued | Obsolete | 7Alternatives availableSee Alternatives |
You searched one part. Parter watches your whole BOM.
All your BOM, at once
Parter maps every line to live stock, lead time, lifecycle and compliance data across the entire market — not part by part.
Hear about problems before they hit production
Allocation, EOL and last-time-buy notices surface the moment they appear, not when your buyer's PO bounces.
Qualified replacements in minutes, not days
Every at-risk line gets form-fit-function matches like the ones above — deltas flagged, evidence attached. Review, push to your BOM, and Parter starts watching the new part too.
Frequently asked questions
Yes. The onsemi MMSZ5242B is marked obsolete, so the manufacturer has discontinued it and any remaining supply is limited to distributor stock. The qualified second sources on this page are active parts you can design in today.
The closest qualified second sources for the onsemi MMSZ5242B are the MMSZ5242BT1G (onsemi) and the MMSZ5242B-7-F (Diodes Incorporated), out of 3 matched alternatives in total. Each is compared against the original on fit, form and function in the table above.
Not always. The alternatives to the MMSZ5242B are matched on function but can differ in package, pinout or a key parameter, so review the fit/form/function notes in the table and the datasheet before designing one in.
The MMSZ5242B (onsemi) is a part in the Diodes category. This page lists qualified, cross-referenced replacements for it with a side-by-side comparison.
Schedule a demo
See Parter in action
Discover how Parter can help your hardware team:
- Streamline your hardware operations with AI
- Detect and prevent lifecycle disruptions
- Accelerate product development
- Stay compliant and production-ready