Microchip Technology UM4906C

Overview

UM4906C from Microsemi is a high-power RF PIN diode designed for low-distortion switching and attenuation in HF–S-band systems. It features 1000 V reverse voltage rating, 37.5 W power dissipation (at 25°C stud temperature), 0.5 Ω typical series resistance at 100 MHz, >5 µs carrier lifetime, and 3 pF capacitance at 100 V reverse bias. It is deployed in UHF phase shifters and megawatt peak-power duplexers.

For engineers reviewing the UM4906C datasheet, UM4906C pinout, UM4906C application, or UM4906C equivalent, key selection criteria include thermal path efficiency (shorter than UM4000 series), reverse voltage capability, RF power handling at S-band, and compatibility with automatic insertion equipment in high-reliability RF front-end assemblies.

Technical Context

The UM4906C uses a non-cavity, thermally matched PIN structure with a thick intrinsic region enabling long carrier lifetime (>5 µs) and high charge storage. Its low series resistance (0.5 Ω typ. @ 100 MHz) and low capacitance (3 pF @ 100 V) support efficient RF control under modest DC bias.

It operates with reverse voltage up to 1000 V and handles pulsed RF voltages well beyond applied bias due to high peak power tolerance (100 kW, 1 µs pulse). The "C" suffix denotes Style C package - an isolated stud-mount configuration optimized for high thermal conductivity and DC isolation.

Key Specifications

Pinout & Package

UM4906C uses Style C package: isolated stud-mount metal case with two axial leads - anode and cathode - mounted on opposite sides of a ceramic-insulated copper stud. Thermal path from chip to stud is shortened versus UM4000 series, improving power derating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-power RF PIN diode applications.

Compared with UM4006C, UM4906C delivers +50% power headroom and faster thermal response; compared with UMX4906C, it shares all electrical and mechanical characteristics except surface finish - making UM4906C the baseline high-reliability option for non-RoHS-sensitive RF subsystems.

Availability

UM4906C is available at Aetrix Electronics and suitable for UHF radar phase shifters, megawatt peak-power duplexers, antenna couplers, and reconfigurable RF filter networks requiring stable component supply across extended production lifecycles.

Supply support for UM4906C 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, RF, and timing solutions for aerospace, defense, and industrial markets.

The UM4900 series was developed specifically for high-power microwave switching and attenuation in mission-critical radar and communications infrastructure, emphasizing thermal robustness, RF linearity, and long-term reliability under extreme RF stress.

FAQ

What is the maximum reverse voltage rating for UM4906C?

The UM4906C has a 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. The 1000 V capability allows UM4906C to safely isolate RF paths in high-voltage transmitter stages, including S-band radar modulators and high-power amplifier output switches. Operating above this voltage risks irreversible junction breakdown.

How does UM4906C differ from UM4006C in thermal performance?

UM4906C achieves 37.5 W power dissipation at 25°C stud temperature, versus 25 W for UM4006C - a 50% increase enabled by a shorter thermal path between die and stud. This is documented in the Absolute Maximum Ratings table (Condition D) and confirmed in the Typical Power Ratings graph on page 4. The improved thermal path directly lowers junction-to-stud thermal resistance, allowing UM4906C to sustain higher average RF power in compact radar front-ends.

Is UM4906C compatible with automatic insertion equipment?

Yes, UM4906C is explicitly stated in the KEY FEATURES section to be compatible with automatic insertion equipment. Its Style C package - with axial leads and rigid stud-mount geometry - meets mechanical tolerances required for pick-and-place and axial lead insertion systems. This compatibility simplifies high-volume assembly of RF modules such as phased-array antenna control boards where UM4906C is used in switching matrices.

What is the typical series resistance of UM4906C and why does it matter?

The typical series resistance of UM4906C is 0.5 Ω measured at 100 MHz and 100 mA forward current. As specified in the Electrical Parameters table (page 2), this low R_S directly determines insertion loss in series-switch configurations and power dissipation under RF current. In practical use, it enables UM4906C to maintain <0.2 dB loss in 50 Ω systems up to 2 GHz - critical for low-noise radar receiver protection circuits and high-efficiency transmit path switching.

Does UM4906C require a heatsink, and what is its thermal resistance?

Yes, UM4906C requires a heatsink when operating near its 37.5 W power limit. Its thermal resistance is 4°C/W at 25°C stud temperature (Condition D), per the Absolute Maximum Ratings table. This value assumes direct metal-to-metal contact between the isolated stud and a thermally conductive chassis or heatsink. Without adequate heatsinking, junction temperature will exceed safe limits rapidly - especially in CW or high-duty-cycle pulsed applications where UM4906C is commonly deployed.