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Microchip Technology 1N4745UR-1/TR
- Part No.:
- 1N4745UR-1/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-213AB, MELF (Glass)
- Datasheet:
-
1N4745UR-1/TR.pdf
- Description:
- DIODE ZENER 16V 1W DO213AB
- Quantity:
- Payment:
- Shipping:
Inventory:3,158
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Product details
Overview
1N4745UR-1/TR from Microsemi is a surface-mount 1.0 W glass Zener diode with nominal Zener voltage of 16 V, ±5% tolerance (A-suffix), 16 Ω dynamic impedance at 15.5 mA test current, and maximum reverse leakage of 5 µA at 12.2 V. It features hermetic DO-213AB MELF packaging, operates from –65°C to +175°C, and is used for precision voltage regulation in high-density power supply feedback loops.
For engineers reviewing the 1N4745UR-1/TR datasheet, 1N4745UR-1/TR pinout, 1N4745UR-1/TR application, or 1N4745UR-1/TR equivalent, key selection criteria include Zener voltage accuracy, thermal resistance (130°C/W on FR4), surge current rating (700 mA), low capacitance, and RoHS-compliant matte-tin terminations.
Technical Context
This device functions as a two-terminal voltage reference diode operating in reverse breakdown. Its Zener voltage is specified at 15.5 mA (IZT), with knee current IZK = 0.25 mA and corresponding ZZK = 16 Ω - confirming sharp breakdown characteristics suitable for stable regulation across varying load currents.
The DO-213AB glass MELF package provides hermetic sealing, inherent radiation hardness per MicroNote 050, and low parasitic inductance/capacitance. Thermal performance is defined relative to end-cap temperature (TEC) and ambient (TA), with derating required above 45°C on FR4 board using recommended pad layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 16 V ±5% at 15.5 mA - sets precise reference point for feedback networks in DC-DC converters and LDOs. |
| Power Dissipation | 1.0 W at TC ≤ 125°C - supports continuous regulation in compact, thermally constrained layouts. |
| Dynamic Impedance (ZZT) | 16 Ω at IZT = 15.5 mA - ensures minimal output voltage variation under dynamic load changes. |
| Reverse Leakage (IR) | 5 µA max at VR = 12.2 V - maintains low quiescent current in standby or low-power modes. |
| Surge Current (IS) | 700 mA (½-sine, 1/120 s) - withstands transient overvoltage events without degradation. |
| Operating Temperature | –65°C to +175°C - enables use in automotive engine control, downhole, and industrial environments. |
| Package | DO-213AB glass MELF - leadless, hermetically sealed, ESD-insensitive, and compatible with reflow soldering (260°C/10 s). |
Pinout & Package
DO-213AB glass MELF package: cylindrical, leadless, cathode band marked on one end; polarity critical - banded end must be anode for forward bias, cathode for Zener operation (banded end positive during regulation).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Zener regulation terminal | Connected to regulated voltage node; reverse-biased during operation; requires proper thermal pad layout per Microsemi spec. |
| Anode (unbanded end) | Reference return path | Typically tied to ground or feedback divider low-side; completes Zener current path and defines regulation reference point. |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic glass MELF construction | Eliminates moisture ingress and long-term parameter drift; qualified for high-reliability applications per source control drawing (SCD). |
| Radiation hardness | Inherently radiation-hardened per MicroNote 050 - suitable for aerospace and defense systems without additional screening. |
| Tight voltage tolerance | ±5% (A-suffix) enables accurate setpoint control in closed-loop regulators without post-calibration trimming. |
| Low dynamic impedance | 16 Ω at rated test current ensures stable output voltage under ±20% load current variation in SMPS feedback paths. |
| RoHS-compliant termination | Matte-tin plating meets MIL-STD-750 Method 2026 - ensures reliable solder wetting and intermetallic formation in lead-free assembly. |
Applications
| Switch-Mode Power Supply Feedback | Industrial Sensor Reference |
|---|---|
|
Use Scenario: Regulating output voltage in isolated flyback or forward converter secondary-side feedback loop. IC Role / Device Role / Timing Role: Zener reference element in optocoupler-coupled feedback network, setting TL431 or shunt regulator threshold. Use Value: 16 V rating matches common auxiliary rail requirements; ±5% tolerance avoids overvoltage shutdown while maintaining margin for line/load transients. |
Use Scenario: Providing stable excitation voltage for bridge-based pressure or strain sensors in factory automation. IC Role / Device Role / Timing Role: Precision voltage reference for ratiometric sensor signal conditioning, replacing higher-cost IC references where 1% drift is acceptable. Use Value: Hermetic glass package ensures long-term stability in humid or chemically aggressive plant-floor environments. |
| Automotive Engine Control Unit | High-Temperature Industrial Monitoring |
|
Use Scenario: Overvoltage clamp and reference in 12 V battery-supplied microcontroller reset circuitry. IC Role / Device Role / Timing Role: Zener clamping diode protecting MCU VDD pin against load-dump transients up to 40 V. Use Value: 700 mA surge rating absorbs ISO 7637-2 Pulse 5a energy; -65°C to +175°C range covers under-hood thermal extremes. |
Use Scenario: Voltage reference in downhole oil/gas telemetry modules exposed to >150°C ambient. IC Role / Device Role / Timing Role: Stable bias source for analog front-end amplifiers and ADC drivers in harsh-environment data acquisition. Use Value: End-cap thermal resistance of 50°C/W enables direct mounting to heat-conductive metal housings, avoiding PCB delamination. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4745A-TR | Same 16 V ±5%, DO-41 axial package (not surface mount); higher thermal resistance (150°C/W ambient); no hermetic seal. | Used where through-hole assembly or lower-cost non-hermetic solution suffices; unsuitable for high-density SMT or high-reliability sealed enclosures. | Select 1N4745UR-1/TR when MELF footprint, hermeticity, or radiation hardness is required; choose 1N4745A-TR for legacy through-hole designs. |
| SMAJ4745A | Same 16 V ±5%, but in SMA package; higher power rating (1.5 W); plastic body; not hermetically sealed; different thermal profile. | Preferred for cost-sensitive consumer electronics where moisture resistance is less critical and higher surge handling is needed. | Choose SMAJ4745A for higher surge robustness and lower unit cost in non-mission-critical applications; retain 1N4745UR-1/TR for hermetic reliability and radiation tolerance. |
Compared with 1N4745A-TR and SMAJ4745A, the 1N4745UR-1/TR uniquely combines surface-mount DO-213AB geometry, hermetic glass construction, and inherent radiation hardness - making it the only option among the three qualified for aerospace, downhole, and extended-temperature industrial deployments.
Availability
1N4745UR-1/TR is available at Aetrix Electronics and suitable for switch-mode power supplies, automotive engine control units, industrial sensor references, and high-temperature monitoring systems requiring stable component supply and long-lifecycle support.
Supply support for 1N4745UR-1/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-voltage analog components for aerospace, defense, and industrial markets.
The 1N4745UR-1/TR belongs to Microsemi's surface-mount Zener diode family designed specifically for high-density, high-stability voltage regulation in extreme thermal and radiation environments.
FAQ
What is the Zener voltage tolerance of the 1N4745UR-1/TR?
The 1N4745UR-1/TR has a nominal Zener voltage of 16 V with ±5% tolerance, indicated by the "A" suffix in its designation. This tolerance is verified at 15.5 mA test current and 30°C case temperature per Microsemi's electrical characteristics table. The 1N4745UR-1/TR maintains this specification across its full operating temperature range, supporting predictable regulation in feedback circuits without calibration.
Is the 1N4745UR-1/TR RoHS compliant?
Yes, the 1N4745UR-1/TR is RoHS compliant, as confirmed by the "e3" suffix in its full part number variant and Microsemi's documentation. Its terminations use annealed matte-tin plating per MIL-STD-750 Method 2026, ensuring compatibility with lead-free reflow processes. The 1N4745UR-1/TR meets JEDEC J-STD-020 moisture sensitivity level 1 and supports peak solder temperatures up to 260°C for 10 seconds.
What is the maximum steady-state power dissipation for the 1N4745UR-1/TR on a standard FR4 PCB?
The 1N4745UR-1/TR delivers 1.00 W steady-state power dissipation at ambient temperature below 45°C when mounted on FR4 with 1 oz copper and Microsemi's recommended pad layout. Above 45°C, power must be linearly derated per Figure 1 in the datasheet, reaching zero at 125°C ambient. The 1N4745UR-1/TR thermal resistance is 130°C/W junction-to-ambient under these conditions.
Does the 1N4745UR-1/TR have radiation hardness certification?
Yes, the 1N4745UR-1/TR is inherently radiation-hardened per MicroNote 050, a documented Microsemi technical note. This property arises from its hermetic glass MELF construction and material selection - no additional screening is required. The 1N4745UR-1/TR is routinely deployed in satellite power systems and nuclear instrumentation where total ionizing dose (TID) resilience is mandatory.
How is polarity identified on the 1N4745UR-1/TR?
The 1N4745UR-1/TR uses a single cathode band marking on the glass MELF body to indicate polarity. During Zener regulation, the banded end must be connected to the more positive potential (cathode), while the unbanded end serves as the anode (reference return). Reversing polarity subjects the 1N4745UR-1/TR to forward conduction only, preventing regulation and risking thermal overstress if forward current exceeds 200 mA.
1N4745UR-1/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):
- 16 V
- Tolerance:
- ±10%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 16 Ohms
- Current - Reverse Leakage @ Vr:
- 5 µA @ 12.2 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)
1N4745UR-1/TR FAQ
1.How can I place an order for 1N4745UR-1/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4745UR-1/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 1N4745UR-1/TR reliable?
The price and inventory of 1N4745UR-1/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4745UR-1/TR is usually 5 days.
3.What payment methods are accepted for 1N4745UR-1/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4745UR-1/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4745UR-1/TR?
1N4745UR-1/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4745UR-1/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 1N4745UR-1/TR?
For technical support, including 1N4745UR-1/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4745UR-1/TR requirements.
6.How does Aetrix verify that 1N4745UR-1/TR is sourced from the original manufacturer or authorized distributors?
All 1N4745UR-1/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 1N4745UR-1/TR meets industry standards.
7.What is the process for return or replacement of 1N4745UR-1/TR?
All 1N4745UR-1/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4745UR-1/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 1N4745UR-1/TR part is unused and in its original packaging.
Return procedure for 1N4745UR-1/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N4745UR-1/TR Tags
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MMBZ5240B-7-F
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BZT52C5V6T-7
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MMSZ5231B-7-F
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BZX84C3V3LT1G
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MMSZ4682T1G
onsemi
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BZT52C15S-7-F
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MM5Z5V1ST1G
onsemi
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SMAJ4744A-TP
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