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Microchip Technology 1N4742UR/TR
- Part No.:
- 1N4742UR/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-213AB, MELF (Glass)
- Datasheet:
-
1N4742UR/TR.pdf
- Description:
- DIODE ZENER 12V 1W DO213AB
- Quantity:
- Payment:
- Shipping:
Inventory:7,762
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Product details
Overview
1N4742UR/TR from Microsemi is a surface-mount 12 V, ±5% tolerance glass Zener diode in DO-213AB (MELF) package, rated for 1.0 W steady-state power dissipation at 25°C, with 21 mA test current, 9 Ω dynamic impedance at IZT, and 5 μA maximum reverse leakage at 9.1 V. It serves as a precision voltage reference and shunt regulator in low-parasitic, high-density power supply feedback loops.
For engineers reviewing the 1N4742UR/TR datasheet, 1N4742UR/TR pinout, 1N4742UR/TR application, or 1N4742UR/TR equivalent, key selection criteria include Zener voltage accuracy, thermal resistance (130°C/W on FR4), surge current rating (380 mA), cathode-band polarity marking, and RoHS-compliant matte-tin termination.
Technical Context
This device operates as a two-terminal shunt regulator, maintaining stable output voltage across a broad operating current range (0.25–380 mA) and temperature span (−65°C to +175°C). Its hermetically sealed glass MELF construction ensures low capacitance, radiation hardness per MicroNote 050, and immunity to ESD.
The 1N4742UR/TR exhibits a sharp Zener knee with 0.5 mA test current (IZK) and 45 Ω maximum knee impedance (ZZK). It is electrically equivalent to through-hole 1N4742A but packaged in JEDEC DO-213AB for surface-mount compatibility and reduced parasitics.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 12 V ±5% - defines regulated output voltage under nominal bias; critical for feedback loop setpoint accuracy. |
| Power Dissipation (PD) | 1.0 W at TEC < 125°C - limits continuous thermal load without derating on standard FR4 PCBs. |
| Test Current (IZT) | 21 mA - standardized bias point for measuring VZ and dynamic impedance; used in design validation. |
| Dynamic Impedance (ZZT) | 9 Ω @ IZT - determines regulation stiffness; lower value improves line/load transient rejection. |
| Reverse Leakage (IR) | 5 μA @ 9.1 V - sets minimum quiescent current in standby mode; impacts low-power system efficiency. |
| Surge Current (IS) | 380 mA - peak non-repetitive current handling; enables robustness against input transients. |
| Operating Temperature | −65°C to +175°C - supports extended-range industrial, aerospace, and downhole applications. |
Pinout & Package
Package: DO-213AB (Glass MELF), hermetically sealed, leadless cylindrical body with cathode band marking. Dimensions: A = 2.39–2.66 mm (diameter), B = 4.80–5.20 mm (length), C = 0.41–0.55 mm (band width).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode | Forward conduction terminal | Connected to lower-potential node; reverse-biased during Zener operation. |
| Cathode | Zener regulation terminal | Banded end; connected to higher-potential node to enable reverse breakdown at 12 V. |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic glass MELF construction | Enables radiation hardness (per MicroNote 050) and long-term reliability in harsh environments. |
| Low dynamic impedance (9 Ω) | Improves voltage regulation stability under varying load currents in feedback networks. |
| RoHS-compliant matte-tin plating | Ensures solderability per MIL-STD-750 Method 2026 and compatibility with lead-free reflow. |
| High-temperature operation (up to +175°C) | Supports deployment in engine control units, downhole tools, and industrial motor drives. |
| Nonsensitive to ESD | Eliminates need for external ESD protection in board-level assembly and handling. |
Applications
| Switch-Mode Power Supply Feedback | Industrial Sensor Signal Conditioning |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback or forward converter feedback paths using optocoupler-coupled error amplifiers. IC Role / Device Role / Timing Role: Shunt reference providing precise 12 V reference to TL431 or similar error amplifier. Use Value: Tight ±5% tolerance and low ZZT ensure stable regulation despite transformer winding ratio tolerances and load variation. |
Use Scenario: Providing stable excitation voltage to bridge-based pressure/strain sensors in factory automation systems. IC Role / Device Role / Timing Role: Precision voltage reference source for ratiometric analog front-end circuits. Use Value: Hermetic glass package prevents parameter drift in humid or chemically aggressive plant-floor environments. |
| Aerospace Power Management | Downhole Oil & Gas Instrumentation |
Use Scenario: Voltage clamping and overvoltage protection in avionics DC-DC converters exposed to lightning-induced transients. IC Role / Device Role / Timing Role: Transient suppressor and secondary regulation element in redundant power rails. Use Value: 380 mA surge rating and −65°C to +175°C operation meet DO-160 Section 22 requirements. |
Use Scenario: Biasing reference circuits in high-temperature logging tools deployed at >150°C wellbore depths. IC Role / Device Role / Timing Role: High-stability Zener reference in analog-to-digital signal chains. Use Value: Radiation hardness and glass-sealed integrity prevent parametric shift under neutron/gamma exposure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4742A | Same 12 V ±5%, but DO-41 axial-leaded package; higher thermal resistance (150°C/W ambient) and larger footprint. | Preferred for prototyping or through-hole boards; unsuitable for high-density SMT layouts. | Select 1N4742A only when manual assembly or legacy board compatibility is required. |
| SMAJ4742A | Same electrical specs, but in SMA package; higher power rating (1.5 W), larger size, and different thermal profile (junction-to-lead). | Better suited for higher-power dissipation or mixed-technology boards with both SMT and discrete passives. | Choose SMAJ4742A when thermal margin exceeds 1.0 W or when existing layout uses SMA footprints. |
Compared with 1N4742A and SMAJ4742A, the 1N4742UR/TR offers optimal balance of miniaturization (DO-213AB), low parasitics, and proven reliability in hermetic glass-making it preferred for space-constrained, high-reliability SMT designs where thermal management is controlled via pad layout.
Availability
1N4742UR/TR is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, aerospace power management, and downhole instrumentation requiring stable component supply and long-lifecycle support.
Supply support for 1N4742UR/TR 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
Microsemi (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability, radiation-hardened, and high-temperature analog and discrete components.
The 1N4742UR/TR belongs to Microsemi's surface-mount Zener diode family designed for mission-critical voltage regulation in aerospace, defense, oil & gas, and industrial systems demanding hermetic sealing and extended temperature performance.
FAQ
What is the Zener voltage tolerance of the 1N4742UR/TR?
The 1N4742UR/TR has a nominal Zener voltage of 12 V with a tolerance of ±5%, as indicated by the "A" suffix in its full designation. This tolerance is verified at 21 mA test current and 30°C junction temperature, and applies across its full operating temperature range of −65°C to +175°C. The 1N4742UR/TR does not offer tighter tolerances like ±2% or ±1%-those require suffixes "C" or "D", respectively.
How is the 1N4742UR/TR marked for polarity identification?
The 1N4742UR/TR uses a single cathode band painted on the glass MELF body to indicate polarity. During Zener regulation, the banded end must be held at a higher potential than the anode. This marking conforms to JEDEC DO-213AB standards and is visible under standard optical inspection. No alphanumeric part marking is applied-only the cathode band.
What is the maximum surge current rating for the 1N4742UR/TR?
The 1N4742UR/TR has a maximum non-repetitive reverse surge current (IS) of 380 mA, measured using a ½-sine wave pulse of 1/120 second duration at 25°C ambient. This rating enables transient suppression in power rails subject to inductive switching spikes or ESD events, provided duty cycle remains low and average power stays within 1.0 W limits.
Is the 1N4742UR/TR RoHS compliant?
Yes, the 1N4742UR/TR is RoHS compliant, as confirmed by the "e3" suffix in its full manufacturer part number (1N4742AUR,e3). Its terminations use annealed matte-tin plating per MIL-STD-750 Method 2026, and it meets all substance restrictions defined in Directive 2011/65/EU. Full compliance documentation is available from Microchip upon request.
What is the thermal resistance of the 1N4742UR/TR when mounted on FR4?
When mounted on a standard FR4 PCB with 1 oz copper and Microsemi's recommended pad layout, the 1N4742UR/TR has a thermal resistance of 130°C/W from junction to ambient. This value assumes proper copper pour and thermal vias; exceeding this thermal resistance risks junction temperature rise above 125°C, triggering power derating per Figure 1 in the datasheet.
1N4742UR/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- DO-213AB, MELF (Glass)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 12 V
- Tolerance:
- ±10%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 9 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 9.1 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.2 V @ 200 mA
- Operating Temperature:
- -65°C ~ 175°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DO-213AB (MELF, LL41)
1N4742UR/TR FAQ
1.How can I place an order for 1N4742UR/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4742UR/TR 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 1N4742UR/TR reliable?
The price and inventory of 1N4742UR/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4742UR/TR is usually 5 days.
3.What payment methods are accepted for 1N4742UR/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4742UR/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4742UR/TR?
1N4742UR/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4742UR/TR 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 1N4742UR/TR?
For technical support, including 1N4742UR/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4742UR/TR requirements.
6.How does Aetrix verify that 1N4742UR/TR is sourced from the original manufacturer or authorized distributors?
All 1N4742UR/TR 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 1N4742UR/TR meets industry standards.
7.What is the process for return or replacement of 1N4742UR/TR?
All 1N4742UR/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4742UR/TR, 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 1N4742UR/TR part is unused and in its original packaging.
Return procedure for 1N4742UR/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N4742UR/TR Tags
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MMBZ5240B-7-F
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MM5Z5V1ST1G
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