Microchip Technology UM4310B

Overview

UM4310B from Microsemi is a high-voltage PIN diode designed for RF switching and linear attenuator applications in HF–1 GHz systems. It features 1000 V reverse voltage rating, 2.2 pF maximum capacitance at 100 V/1 MHz, 1.5 Ω max series resistance at 100 mA/100 MHz, and 6 µs minimum carrier lifetime - enabling low-distortion signal control in broadband RF power paths.

For engineers reviewing the UM4310B datasheet, UM4310B pinout, UM4310B application, or UM4310B equivalent, key selection criteria include reverse voltage hold-off capability, RF series resistance under forward bias, thermal resistance in stud-mount configurations, and compatibility with low-distortion attenuator topologies requiring transit-time-limited operation below 5 MHz.

Technical Context

The UM4310B employs a thick intrinsic (I) region (≥250 µm) to achieve low distortion by limiting transit-time frequency to below 5 MHz, making it suitable for precision linear RF attenuation. Its non-cavity, thermally matched construction supports stable performance under pulsed RF conditions up to 500 kW peak power.

As a discrete PIN diode, UM4310B operates in forward conduction (low-R_S) or reverse bias (high-R_P, low-C_T) states - not as an integrated switch IC. It requires external DC bias circuitry and is rated for 10 µA max reverse leakage at 1000 V, with parallel resistance ≥200 kΩ at 100 V/100 MHz.

Key Specifications

Pinout & Package

UM4310B is supplied in Style 'B' package: a stud-mounted, isolated metal-can diode with two terminals - anode and cathode - mounted on opposite sides of a thermally conductive base. Thermal path is optimized via ½-inch lead length to 25 °C ambient, achieving θ = 2.5 °C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UM4310C and UM7310B, UM4310B uniquely balances high-voltage hold-off, low series resistance, and long carrier lifetime - making it optimal for HF–UHF linear attenuators requiring <−80 dBc IMD3, whereas alternatives trade off either thermal performance or distortion behavior.

Availability

UM4310B is available at Aetrix Electronics and suitable for HF antenna tuners, broadcast transmitter attenuators, RF test equipment signal routing, and avionics T/R modules requiring stable component supply across extended production cycles.

Supply support for UM4310B 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 RF components for aerospace, defense, and communications infrastructure.

The UM4300 series was developed specifically for high-linearity, high-voltage RF control in military-grade transmitters and broadcast exciters - emphasizing thermal robustness, low distortion, and repeatable RF parameter stability under wide temperature and power ranges.

FAQ

What is the maximum reverse voltage rating for UM4310B?

The UM4310B has a maximum reverse voltage rating of 1000 V at 10 µA leakage current. This rating is confirmed in the Absolute Maximum Ratings table on Page 1 of the official Microsemi datasheet (Rev: 3/30/2009). The 1000 V capability allows UM4310B to safely block high RF voltage swings in antenna tuner and transmitter output stage applications without breakdown.

Does UM4310B have a specified series resistance value, and under what conditions?

Yes, UM4310B has a maximum series resistance (R_S) of 1.5 Ω, measured at 100 mA forward current and 100 MHz frequency. This value is listed in the Electrical Characteristics table on Page 2 of the Microsemi datasheet. The low R_S directly enables low insertion loss in series-attenuator configurations and contributes to high power-handling efficiency in RF switching circuits using UM4310B.

What is the carrier lifetime specification for UM4310B, and why does it matter?

UM4310B specifies a minimum carrier lifetime (τ) of 6.0 µs at 10 mA forward current. As stated in the datasheet, this long lifetime ensures transit-time frequencies remain below 5 MHz - a critical factor for minimizing harmonic distortion in linear RF attenuators. Applications such as SSB voice transmission or precision test signal conditioning rely on this parameter to maintain signal fidelity when using UM4310B in analog gain-control paths.

Which package style corresponds to UM4310B, and what are its thermal characteristics?

UM4310B uses Style 'B' packaging: a stud-mounted, isolated metal-can diode with ½-inch total lead length. Per the Absolute Maximum Ratings table, its thermal resistance (θ) is 2.5 °C/W when mounted with leads extending freely in ambient air at 25 °C. This low thermal resistance supports 10 W continuous power dissipation - verified in the Power Dissipation vs. Lead Temperature graph on Page 3 - making UM4310B suitable for medium-duty RF power control tasks.

How does UM4310B differ from UM7310B in terms of RF performance?

UM4310B differs from UM7310B primarily in three confirmed parameters: UM4310B has lower series resistance (1.5 Ω vs. 3.0 Ω), higher capacitance (2.2 pF vs. 0.7 pF), and longer carrier lifetime (6.0 µs vs. 4.0 µs). These differences make UM4310B better suited for low-distortion, high-power linear attenuators below 100 MHz, while UM7310B favors high-isolation, high-frequency switching above 500 MHz - as documented in the same datasheet's comparative Electrical Characteristics table.