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Microchip Technology 1N4738UR/TR
- Part No.:
- 1N4738UR/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- DO-213AB, MELF (Glass)
- Datasheet:
-
1N4738UR/TR.pdf
- Description:
- DIODE ZENER 8.2V 1W DO213AB
- Quantity:
- Payment:
- Shipping:
Inventory:272
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Product details
Overview
1N4738UR/TR from Microsemi is a surface-mount 1.0 W glass-encapsulated Zener diode with nominal Zener voltage 8.2 V ±5%, 31 mA test current, 4.5 Ω dynamic impedance at IZT, and maximum reverse current of 6 μA at 6.6 V. It operates from −65 °C to +175 °C and is used for precision voltage regulation in high-density power supply feedback loops and reference circuits.
For engineers reviewing the 1N4738UR/TR datasheet, 1N4738UR/TR pinout, 1N4738UR/TR application, or 1N4738UR/TR equivalent, this part delivers stable regulation under wide temperature and current variation, supports RoHS-compliant assembly via e3 suffix, and meets JEDEC DO-213AB MELF packaging requirements for low parasitic performance.
Technical Context
This Zener diode functions as a two-terminal voltage reference device operating in reverse breakdown mode. Its glass hermetic DO-213AB package ensures low leakage (≤6 μA @ 6.6 V), sharp knee impedance (4.5 Ω @ 31 mA), and radiation hardness per MicroNote 050.
It is electrically equivalent to through-hole 1N4738A but optimized for SMT placement with 0.05 g mass, 2.39–2.66 mm diameter (A), and 4.80–5.20 mm length (B). Thermal resistance is 130 °C/W junction-to-ambient on FR4 with recommended pad layout.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Zener Voltage (VZ) | 8.2 V ±5% - sets precise regulation point for feedback networks |
| Test Current (IZT) | 31 mA - defines operating point where Zener voltage and impedance are specified |
| Dynamic Impedance (ZZT) | 4.5 Ω @ IZT - determines output voltage stability under load transients |
| Max Reverse Current (IR) | 6 μA @ 6.6 V - ensures low quiescent loss in standby or low-power modes |
| Power Dissipation | 1.0 W @ TEC < 125 °C - supports continuous regulation in compact thermal environments |
| Operating Temperature | −65 °C to +175 °C - enables use in automotive under-hood and industrial control applications |
| Package | DO-213AB glass MELF - provides hermetic sealing, ESD insensitivity, and low parasitic capacitance |
Pinout & Package
DO-213AB glass MELF package: cylindrical, leadless, cathode band marked on one end; polarity critical-cathode (banded end) must be biased positive relative to anode for Zener operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Reverse-biased terminal | Connected to higher potential node; regulates voltage across anode-cathode when reverse-biased above VZ |
| Anode (unmarked end) | Reference/return terminal | Typically tied to ground or lower-potential rail; completes Zener conduction path |
Key Features
| Feature | Design Value |
|---|---|
| Hermetic glass MELF construction | Enables operation up to +175 °C and eliminates moisture-induced parameter drift |
| Low dynamic impedance (4.5 Ω) | Maintains tight output voltage tolerance (<±0.1 V) across 10–100 mA load current range |
| RoHS-compliant (e3 suffix) | Supports lead-free reflow soldering at 260 °C for 10 s without degradation |
| JEDEC DO-213AB outline | Ensures compatibility with standard MELF pick-and-place tooling and automated optical inspection |
| Radiation-hardened per MicroNote 050 | Validated for use in aerospace and defense systems requiring TID tolerance >100 krad(Si) |
Applications
| Switch-Mode Power Supply Feedback | Industrial Sensor Reference |
|---|---|
Use Scenario: Regulating output voltage in isolated flyback or forward converters using optocoupler feedback. IC Role / Device Role / Timing Role: Zener reference in TL431-like shunt regulator configuration, setting error amplifier threshold. Use Value: 8.2 V nominal voltage matches common TL431 bias requirements; ±5% tolerance ensures stable loop gain across production lots. |
Use Scenario: Providing stable excitation voltage for resistive bridge sensors in factory automation systems. IC Role / Device Role / Timing Role: Precision voltage reference for Wheatstone bridge biasing in 4–20 mA transmitter front-ends. Use Value: Low 6 μA reverse leakage minimizes offset error; hermetic glass package prevents long-term drift in humid environments. |
| Automotive Engine Control Unit | Medical Diagnostic Equipment |
Use Scenario: Overvoltage clamp and reference in 12 V battery-supplied microcontroller power rails. IC Role / Device Role / Timing Role: Zener clamp protecting ADC input or LDO enable pin against load-dump transients. Use Value: −65 °C to +175 °C rating supports under-hood deployment; 1.0 W dissipation handles short-duration surges without failure. |
Use Scenario: Calibration reference in portable ultrasound or ECG signal conditioning stages. IC Role / Device Role / Timing Role: Stable DC reference for analog front-end gain-setting and offset nulling circuits. Use Value: Radiation hardness ensures reliability in X-ray-adjacent subsystems; low noise and sharp knee support sub-mV accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4738A | Same electrical specs, but DO-41 axial-leaded package (not surface mount) | Requires through-hole PCB assembly; unsuitable for high-density layouts | Select only if legacy board design mandates axial leads or manual assembly |
| SMAJ4738A | Same VZ and tolerance, but SMA package (plastic, not glass); 1.5 W PD; higher CJ | Higher surge capability but reduced temperature range (−65 °C to +150 °C) and no radiation hardness | Prefer for cost-sensitive consumer designs where hermeticity and radiation tolerance are noncritical |
Compared with 1N4738A and SMAJ4738A, the 1N4738UR/TR uniquely combines SMT compatibility, hermetic glass reliability, extended temperature range, and radiation hardness-making it the only choice for space-constrained, high-reliability industrial and aerospace voltage references.
Availability
1N4738UR/TR is available at Aetrix Electronics and suitable for switch-mode power supplies, industrial sensor interfaces, automotive engine control units, and medical diagnostic equipment requiring stable component supply across extended temperature and lifecycle demands.
Supply support for 1N4738UR/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 analog and mixed-signal components for aerospace, defense, and industrial markets.
The 1N4738UR/TR belongs to Microsemi's surface-mount Zener diode family designed for high-density, low-parasitic voltage regulation in mission-critical systems where hermeticity, temperature resilience, and radiation tolerance are mandatory.
FAQ
What is the Zener voltage tolerance for 1N4738UR/TR?
The 1N4738UR/TR has a nominal Zener voltage of 8.2 V with a tolerance of ±5%, as indicated by the "A" suffix in its full designation. This tolerance is verified at 31 mA test current and 30 °C case temperature, and applies across the full operating temperature range of −65 °C to +175 °C. The 1N4738UR/TR maintains this specification due to its glass-hermetic construction and process-controlled doping.
Does 1N4738UR/TR support lead-free soldering processes?
Yes, the 1N4738UR/TR carries the "e3" RoHS-compliant suffix, indicating annealed matte-tin plating compatible with lead-free reflow soldering. It withstands peak temperatures of 260 °C for up to 10 seconds per J-STD-020, and its DO-213AB glass body remains unaffected by thermal cycling during standard SMT assembly.
How does the DO-213AB package of 1N4738UR/TR differ from DO-41?
The 1N4738UR/TR uses the DO-213AB glass MELF package-cylindrical, leadless, and surface-mountable-whereas DO-41 is axial-leaded and through-hole. DO-213AB offers lower parasitic inductance/capacitance, higher density placement, and superior thermal coupling to PCB pads. Electrically, both share identical Zener characteristics, but mechanical mounting and board space utilization differ fundamentally.
What is the maximum steady-state power dissipation for 1N4738UR/TR?
The 1N4738UR/TR is rated for 1.0 W steady-state power dissipation at end-cap temperature (TEC) below 125 °C, or at ambient temperature (TA) below 45 °C when mounted on FR4 with 1 oz copper and the recommended pad layout. Derating follows a linear curve beyond those points, reaching zero dissipation at 175 °C ambient per Figure 1 in the original datasheet.
Is 1N4738UR/TR suitable for high-reliability aerospace applications?
Yes, the 1N4738UR/TR is inherently radiation-hardened per MicroNote 050 and qualified for high-reliability use. Optional screening to MIL-PRF-19500 (e.g., JANTXV level) is available with prefix "MV", and its hermetic glass package ensures long-term parameter stability in vacuum or high-humidity environments typical of satellite and avionics systems.
1N4738UR/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):
- 8.2 V
- Tolerance:
- ±10%
- Power - Max:
- 1 W
- Impedance (Max) (Zzt):
- 4.5 Ohms
- Current - Reverse Leakage @ Vr:
- 10 µA @ 6 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)
1N4738UR/TR FAQ
1.How can I place an order for 1N4738UR/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4738UR/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 1N4738UR/TR reliable?
The price and inventory of 1N4738UR/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4738UR/TR is usually 5 days.
3.What payment methods are accepted for 1N4738UR/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4738UR/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4738UR/TR?
1N4738UR/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4738UR/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 1N4738UR/TR?
For technical support, including 1N4738UR/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4738UR/TR requirements.
6.How does Aetrix verify that 1N4738UR/TR is sourced from the original manufacturer or authorized distributors?
All 1N4738UR/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 1N4738UR/TR meets industry standards.
7.What is the process for return or replacement of 1N4738UR/TR?
All 1N4738UR/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4738UR/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 1N4738UR/TR part is unused and in its original packaging.
Return procedure for 1N4738UR/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N4738UR/TR Tags
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MM5Z5V1ST1G
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