Microchip Technology 1N5345C/TR8

Overview

1N5345C/TR8 from Microsemi is a 5 W axial-leaded silicon Zener diode with a nominal regulation voltage of 8.7 V, ±2% tolerance (C suffix), 150 mA maximum Zener current (IZM), 2.0 Ω maximum dynamic impedance (ZZ) at 150 mA test current, and operates across -65°C to +150°C. It serves as a precision voltage reference in power supply feedback loops and overvoltage protection circuits.

For engineers reviewing the 1N5345C/TR8 datasheet, 1N5345C/TR8 pinout, 1N5345C/TR8 application, or 1N5345C/TR8 equivalent, key selection criteria include Zener voltage tolerance, thermal resistance (25 °C/W junction-to-lead), surge current rating (545 A), voltage regulation (ΔVZ = 0.20 V), and RoHS-compliant matte-tin plating per MIL-STD-750.

Technical Context

This device functions as a two-terminal voltage regulator operating in reverse breakdown. Its Zener voltage is specified at 150 mA test current (IZT) with 2.0 Ω dynamic impedance (ZZ), and exhibits minimal voltage variation (ΔVZ = 0.20 V) between 10% and 50% of IZM. The cathode is marked by a band, requiring the banded end to be biased positive relative to the anode.

Thermal performance is defined for 3/8" (10 mm) lead length from body (25 °C/W junction-to-lead) and FR4 PCB mounting (85 °C/W junction-to-ambient). It withstands 8.3 ms half-sine surge currents up to 545 A and maintains regulation under steady-state 5 W dissipation at TL < 25°C.

Key Specifications

Pinout & Package

Package: Axial-leaded T-18 plastic case (void-free UL94V-0 epoxy), cathode indicated by band, RoHS-compliant matte-tin plating, weight 0.7 g.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Zener diode applications.

Compared with 1N5345B/TR8, the 1N5345C/TR8 delivers tighter regulation for critical feedback paths; compared with MMSZ5236ET1G, it supports 10× higher power and robust transient handling but requires axial through-hole layout.

Availability

1N5345C/TR8 is available at Aetrix Electronics and suitable for switching power supplies, overvoltage protection circuits, industrial sensor excitation, and programmable reference sources requiring stable component supply and long-term obsolescence management.

Supply support for 1N5345C/TR8 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, mixed-signal, and RF solutions for aerospace, defense, and industrial markets.

The 1N53xx series was designed for ruggedized voltage regulation in harsh-environment power systems, emphasizing thermal robustness, surge resilience, and JEDEC-standardized interchangeability.

FAQ

What is the Zener voltage tolerance of the 1N5345C/TR8?

The 1N5345C/TR8 has a Zener voltage tolerance of ±2%, as indicated by the "C" suffix per Microsemi's documentation. This means its actual regulation voltage falls between 8.526 V and 8.874 V at 25°C with 150 mA test current. The tighter tolerance supports precision applications like feedback references where output stability is critical. Unlike the B-suffix variant (±5%), the C version reduces system-level calibration burden and improves overall voltage accuracy in regulated supplies.

How is the 1N5345C/TR8 packaged and what does "TR8" signify?

The "TR8" suffix on 1N5345C/TR8 indicates tape-and-reel packaging compliant with EIA-296 standards, using 8 mm wide carrier tape. The device itself uses an axial-leaded T-18 plastic case with matte-tin plated leads, weighing 0.7 g. This format enables automated surface-mount assembly despite the through-hole lead form, supporting high-volume manufacturing while maintaining legacy board compatibility. The TR8 configuration includes orientation control and pocket depth optimized for pick-and-place feeders.

What is the maximum surge current rating for the 1N5345C/TR8?

The 1N5345C/TR8 is rated for a maximum non-recurrent surge current (IZSM) of 545 A, defined as the peak of an 8.3 ms half-sine waveform. This rating reflects its ability to absorb transient energy without parametric shift or catastrophic failure. It is validated under standardized test conditions and directly supports use in automotive load-dump protection and industrial power-line surge suppression where short-duration overcurrent events occur. Derating is not required for single-event surges within this specification.

Does the 1N5345C/TR8 require dry-pack moisture protection?

No, the 1N5345C/TR8 has a moisture sensitivity level (MSL) of Level 1 per IPC/JEDEC J-STD-020B, meaning it does not require dry-packaging or floor-life controls prior to soldering. Its void-free thermosetting epoxy body inherently resists moisture absorption, eliminating bake-out steps and simplifying handling in both prototyping and production environments. This characteristic also supports compatibility with standard reflow profiles without risk of popcorning or delamination.

What is the thermal resistance specification for the 1N5345C/TR8?

The 1N5345C/TR8 has a thermal resistance of 25 °C/W junction-to-lead when measured at 3/8" (10 mm) lead length from the body, and 85 °C/W junction-to-ambient when mounted on a standard FR4 PCB with 1 oz copper, 4 mm² pads, and 1 mm × 25 mm traces. This dual specification enables accurate thermal modeling: the lower value applies when leads serve as primary heat paths (e.g., chassis-mounted), while the higher value guides PCB layout for standalone operation. Both values are measured per JEDEC standards and confirmed in Microsemi's datasheet Rev D.