Microchip Technology UMX512

Overview

UMX512 from Microsemi is a surface-mount MELF-packaged high-power PIN diode designed for RF switching and attenuation in HF–2 GHz systems. It features 500 V breakdown voltage, 1.5 pF capacitance at 50 V, 0.30 Ω max series resistance at 100 mA, 0.12 Ω typical at 200 mA, and 4.0 μs typical carrier lifetime - enabling low-loss T/R control in satellite beam-steering and frequency-hopping radios.

For engineers reviewing the UMX512 datasheet, UMX512 pinout, UMX512 application, or UMX512 equivalent, key selection criteria include its low-inductance full-face bonded chip, RoHS-compliant matte tin terminations, hermetic ceramic MELF package, and verified performance in MRI switching and switch-filter banks requiring >1 million hour MTBF.

Technical Context

The UMX512 operates as a current-controlled RF switch with intrinsic layer optimized for fast carrier recombination (4.0 μs typical τ_L) and minimal stored charge. Its low C_T (1.5 pF @50 V) and ultra-low R_S (0.12 Ω typ @200 mA) enable high-isolation, low-insertion-loss operation up to 2 GHz.

Thermal resistance of 15 °C/W allows sustained 1 A pulsed forward current without exceeding 150 °C junction temperature. The hermetically sealed MELF package uses square-end terminations compatible with standard SMT pick-and-place equipment and reflow profiles up to 260 °C.

Key Specifications

Pinout & Package

The UMX512 is a two-terminal MELF diode housed in a hermetically sealed ceramic package with square-end matte tin terminations. Dimensions: A = 2.03–2.41 mm (length), B = 2.92–3.43 mm (diameter), C = 0.20–0.76 mm (termination thickness).

Key Features

Applications

Equivalent & Alternatives

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

Compared with UMX509–F and UMX504–F, the UMX512 delivers the best balance of low C_T, ultra-low R_S, and moderate τ_L for 2 GHz switch-filter banks requiring both speed and 500 V standoff - making it the default choice for satellite and military radio front-ends.

Availability

UMX512 is available at Aetrix Electronics and suitable for cellular infrastructure, satellite communications, frequency-hopping radios, and MRI systems requiring stable component supply and long-term lifecycle assurance.

Supply support for UMX512 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, RF, and timing solutions for aerospace, defense, and industrial markets.

The UMX502–UMX812 family was engineered specifically for high-power, high-frequency RF switching in mission-critical systems where hermetic sealing, magnetic purity, and million-hour reliability are mandatory.

FAQ

What is the maximum continuous forward current rating for UMX512?

The UMX512 is rated for 1 A forward current under 1 µs pulse conditions per the datasheet. It does not specify a continuous DC current rating due to thermal limitations in the MELF package. For sustained operation, design must limit average power using the 15 °C/W thermal resistance and 150 °C max junction temperature - typically supporting ≤500 mA average in still air with adequate copper pour. Always verify thermal performance in the final PCB layout.

Does UMX512 have a specified junction-to-case thermal resistance (θ_JC)?

No, the UMX512 datasheet provides only junction-to-ambient thermal resistance (θ_JA) of 15 °C/W maximum, measured on a standard test board. No θ_JC value is published because the MELF package lacks a defined case surface for thermal interface; heat dissipation occurs radially through the ceramic body and terminations into the PCB copper. Thermal modeling must use θ_JA with board-specific copper area and airflow assumptions.

Is UMX512 suitable for use in MRI systems?

Yes - the UMX512 is explicitly designated as a low-magnetic Cer-Met MELF device in the datasheet, making it suitable for MRI gradient coil switching where ferromagnetic materials would distort the static magnetic field or cause image artifacts. Its hermetic seal and hard glass passivation also ensure long-term reliability under repeated high-current pulsing in clinical environments.

What is the meaning of "–F" suffix in UMX512–F?

The "–F" suffix in UMX512–F denotes the standard RoHS-compliant version with matte tin terminal finish, as confirmed in the datasheet's Product Overview section. It distinguishes this variant from non-RoHS or special-finish versions (e.g., gold-plated). All electrical specifications, package dimensions, and reliability data in the UMX502–UMX812 datasheet apply specifically to the –F suffix parts.

How does UMX512 compare to UMX812–F in terms of RF performance?

UMX512–F has lower capacitance (1.5 pF vs. 1.3 pF) and lower series resistance (0.12 Ω typ @200 mA vs. 0.25 Ω) than UMX812–F, giving it superior insertion loss and bandwidth. However, UMX812–F offers longer carrier lifetime (5.5 μs vs. 4.0 μs), making it better suited for low-distortion attenuators. Both share identical 500 V V_BR and 15 °C/W θ_JA, but UMX512–F is optimized for speed-critical switching.