My Inquiry
My Account
Microchip Technology 1N4477US/TR
- Part No.:
- 1N4477US/TR
- Manufacturer:
- Microchip Technology
- Category:
- Single Zener Diodes
- Package:
- SQ-MELF, A
- Datasheet:
-
1N4477US/TR.pdf
- Description:
- DIODE ZENER 33V 1.5W D5A
- Quantity:
- Payment:
- Shipping:
Inventory:158
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
1N4477US/TR from Microsemi is a hermetically sealed, voidless glass MELF surface-mount Zener diode rated for 1.5 W steady-state power dissipation, with a nominal Zener voltage of 33.0 V at 7.5 mA test current, ±5% tolerance, and maximum dynamic impedance of 25 Ω at IZT. It operates across –65 °C to +175 °C junction temperature and is qualified to MIL-PRF-19500/406 (JANTXV level), serving as a precision voltage reference in high-reliability military power regulation circuits.
For engineers reviewing the 1N4477US/TR datasheet, 1N4477US/TR pinout, 1N4477US/TR application, or 1N4477US/TR equivalent, this page delivers verified electrical parameters, military-grade qualification status, thermal resistance (20 °C/W), reverse leakage (<0.25 µA at 26.4 V), and surge current rating (0.43 A at 8.3 ms) - all critical for aerospace power supply design and radiation-hardened system validation.
Technical Context
This device belongs to Microsemi's MIL-qualified 1N4460US–1N4496US series, featuring internal Category I metallurgical bonds and triple-layer passivation for enhanced reliability. Its Zener breakdown mechanism provides stable regulation over wide current (0.05–0.43 A) and temperature (–65 °C to +175 °C) ranges, with low thermal resistance (20 °C/W) enabling efficient heat transfer through the end-cap.
The 1N4477US/TR uses a D-5A MELF glass package with cathode band marking and Sn/Pb or RoHS-compliant matte tin terminations. It exhibits non-sensitive ESD behavior per MIL-STD-750 Method 1020 and inherent radiation hardness per MicroNote 050 - key for space-qualified and nuclear instrumentation applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Nominal Zener Voltage (VZ) | 33.0 V at 7.5 mA - defines precise regulation point for feedback loops in DC-DC converters. |
| Power Dissipation (PD) | 1.5 W @ 25 °C - sets maximum continuous power handling before thermal derating begins. |
| Dynamic Impedance (ZZT) | 25 Ω @ IZT - determines output voltage stability under load transients. |
| Reverse Leakage (IR) | <0.25 µA @ 26.4 V - ensures minimal error current in high-impedance reference paths. |
| Thermal Resistance (RθJEC) | 20 °C/W - enables accurate junction temperature estimation from end-cap measurements. |
| Surge Current (IZSM) | 0.43 A @ 8.3 ms - supports transient overvoltage clamping without failure. |
| Operating Temperature | –65 °C to +175 °C - validates use in extreme-environment avionics and downhole electronics. |
Pinout & Package
The 1N4477US/TR is a two-terminal axial device in the D-5A MELF (Metal Electrode Leadless Face) glass package, measuring 0.091–0.103 inches in diameter and 0.168–0.200 inches in length. Cathode is marked by a single dark band; no anode/cathode labeling beyond polarity band.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Cathode (banded end) | Zener breakdown terminal | Connected to regulated output node; reverse-biased operation requires this terminal at higher potential than anode. |
| Anode (unbanded end) | Reference ground/reference return | Typically tied to system ground or feedback divider low-side; completes Zener conduction path. |
Key Features
| Feature | Design Value |
|---|---|
| Voidless hermetic glass seal | Prevents moisture ingress and long-term parameter drift in humid or vacuum environments. |
| Triple-layer passivation | Enhances surface insulation integrity and suppresses leakage currents under high humidity or contamination. |
| Category I metallurgical bond | Ensures mechanical robustness and thermal cycling reliability up to 1000 cycles between –65 °C and +175 °C. |
| MIL-PRF-19500/406 JANTXV qualification | Validates screening, testing, and traceability for mission-critical defense electronics procurement. |
| Radiation hardness (per MicroNote 050) | Supports operation in total ionizing dose (TID) environments exceeding 100 krad(Si) without parametric shift. |
Applications
| Aerospace Power Regulation | Downhole Instrumentation |
|---|---|
Use Scenario: Regulating auxiliary rail voltage in satellite power management units exposed to thermal cycling and radiation. IC Role / Device Role / Timing Role: Precision voltage reference and overvoltage clamp in isolated DC-DC feedback networks. Use Value: Stable 33.0 V reference with <0.25 µA leakage ensures minimal error in 24-bit ADC biasing and telemetry signal conditioning. | Use Scenario: Providing stable bias for pressure/temperature sensor front-ends in oil-well logging tools operating at 175 °C ambient. IC Role / Device Role / Timing Role: High-temperature Zener shunt regulator maintaining sensor excitation voltage under extreme thermal stress. Use Value: Junction temperature range (–65 °C to +175 °C) and 20 °C/W RθJEC enable direct mounting on ceramic substrates with predictable thermal performance. |
| Military Radar Bias Supply | Nuclear Instrumentation |
Use Scenario: Generating stable gate bias for GaN RF power amplifiers in airborne radar transceivers subject to EMI and vibration. IC Role / Device Role / Timing Role: Low-noise, low-impedance Zener reference replacing IC-based regulators where radiation tolerance is mandatory. Use Value: 25 Ω ZZT and MIL-qualified construction ensure consistent bias point despite RF coupling and mechanical shock. | Use Scenario: Establishing calibrated reference voltage in neutron detection pulse-shaping circuits within reactor control systems. IC Role / Device Role / Timing Role: Radiation-hardened voltage clamp protecting front-end op-amps from transient spikes during particle events. Use Value: Inherent radiation hardness (MicroNote 050) and non-sensitive ESD behavior eliminate need for external hardening components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Zener voltage regulation applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 1N4763A | 33 V, ±5%, 1 W, DO-41 package, no MIL qualification | Limited to commercial-grade industrial controls; lacks radiation hardness and extended temperature range | Select when cost and volume outweigh military reliability requirements |
| SMF33A | 33 V, ±5%, 400 W peak power, SOD-123 package, TVS-rated, not Zener-regulated | Designed for transient suppression only; unsuitable for precision regulation due to higher leakage and wider VBR tolerance | Select only for overvoltage protection - not as a replacement for voltage reference function |
Compared with 1N4477US/TR, the 1N4763A offers lower cost but sacrifices MIL qualification, thermal range, and radiation tolerance; the SMF33A provides superior surge handling but cannot replace 1N4477US/TR in regulation-critical roles due to absence of stable Zener knee and higher dynamic impedance.
Availability
1N4477US/TR is available at Aetrix Electronics and suitable for aerospace power regulation, downhole instrumentation, military radar bias supply, and nuclear instrumentation requiring stable component supply with full traceability and long-term lifecycle support.
Supply support for 1N4477US/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 Corporation (now part of Microchip Technology) is a U.S.-based semiconductor company specializing in high-reliability analog and mixed-signal ICs, discrete devices, and radiation-hardened components for defense, aerospace, and industrial markets.
The 1N4477US/TR belongs to Microsemi's MIL-PRF-19500/406-qualified Zener diode family, engineered specifically for voltage regulation in mission-critical systems where failure is not an option - including launch vehicles, nuclear facilities, and strategic communications infrastructure.
FAQ
What is the Zener voltage tolerance for 1N4477US/TR?
The 1N4477US/TR has a nominal Zener voltage of 33.0 V with a standard tolerance of ±5%, as confirmed in the Electrical Characteristics table on Page 3 of T4-LDS-0183-1. No suffix indicates 5% tolerance; tighter tolerances (±2% or ±1%) require different part numbers (e.g., 1N4477USC or 1N4477USD). This tolerance directly impacts regulation accuracy in feedback networks using the 1N4477US/TR.
Is 1N4477US/TR RoHS compliant?
The 1N4477US/TR is available in both RoHS-compliant and non-RoHS versions. Per the nomenclature guide on Page 2, the "e3" suffix denotes RoHS compliance, applicable only to commercial-grade parts. The TR suffix in 1N4477US/TR indicates tape-and-reel packaging but does not specify RoHS status - confirmation requires checking the full ordering code (e.g., 1N4477US/TR/e3) and verifying against Microsemi's official documentation for that specific reel lot.
What is the maximum reverse leakage current for 1N4477US/TR?
The maximum reverse leakage current (IR) for 1N4477US/TR is 0.25 µA at a reverse voltage (VR) of 26.4 V, as specified in the Electrical Characteristics table on Page 3. This value is measured at 25 °C case temperature and reflects the device's ability to maintain high-impedance blocking behavior - critical when the 1N4477US/TR is used in precision reference dividers or low-power sensor biasing circuits.
Does 1N4477US/TR have MIL-PRF-19500/406 qualification?
Yes, the 1N4477US/TR is qualified per MIL-PRF-19500/406 at JANTXV level, as stated in the DESCRIPTION section on Page 1 and confirmed in the Qualification Levels list. This includes rigorous screening for vibration, thermal shock, and burn-in, making the 1N4477US/TR suitable for flight-critical subsystems where the 1N4477US/TR must operate without degradation under extreme environmental stress.
What is the thermal resistance junction-to-end cap for 1N4477US/TR?
The thermal resistance junction-to-end cap (RθJEC) for 1N4477US/TR is 20 °C/W, as listed in the Maximum Ratings table on Page 1. This parameter enables thermal modeling of the 1N4477US/TR when mounted on a heatsink or metal-core PCB, allowing engineers to calculate junction temperature rise above end-cap temperature - essential for ensuring long-term reliability in high-power-density designs using the 1N4477US/TR.
1N4477US/TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Microchip Technology
- Series:
- -
- Package/Case:
- SQ-MELF, A
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Voltage - Zener (Nom) (Vz):
- 33 V
- Tolerance:
- ±5%
- Power - Max:
- 1.5 W
- Impedance (Max) (Zzt):
- 25 Ohms
- Current - Reverse Leakage @ Vr:
- 50 nA @ 26.4 V
- Voltage - Forward (Vf) (Max) @ If:
- 1.5 V @ 1 A
- Operating Temperature:
- -65°C ~ 175°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- D-5A
1N4477US/TR FAQ
1.How can I place an order for 1N4477US/TR through Aetrix?
Please submit a Request for Quotation (RFQ) for 1N4477US/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 1N4477US/TR reliable?
The price and inventory of 1N4477US/TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 1N4477US/TR is usually 5 days.
3.What payment methods are accepted for 1N4477US/TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 1N4477US/TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 1N4477US/TR?
1N4477US/TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 1N4477US/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 1N4477US/TR?
For technical support, including 1N4477US/TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 1N4477US/TR requirements.
6.How does Aetrix verify that 1N4477US/TR is sourced from the original manufacturer or authorized distributors?
All 1N4477US/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 1N4477US/TR meets industry standards.
7.What is the process for return or replacement of 1N4477US/TR?
All 1N4477US/TR units undergo pre-shipment inspection (PSI). If there is an issue with 1N4477US/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 1N4477US/TR part is unused and in its original packaging.
Return procedure for 1N4477US/TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
1N4477US/TR Tags
-
MMBZ5240B-7-F
Diodes Incorporated
-
BZT52C5V6T-7
Diodes Incorporated
-
MMSZ5231B-7-F
Diodes Incorporated
-
BZT52C15-7-F
Diodes Incorporated
-
BZX84C3V3LT1G
onsemi
-
MMSZ5245BS-7-F
Diodes Incorporated
-
MMSZ4682T1G
onsemi
-
BZT52C15S-7-F
Diodes Incorporated
-
MM5Z5V1ST1G
onsemi
-
SMAJ4744A-TP
Micro Commercial Co
-
BZT52C3V6LP-7
Diodes Incorporated
-
SMAZ12-13-F
Diodes Incorporated
Tech Hub
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
