Microchip Technology UM4002B

Overview

UM4002B from Microsemi is a high-power RF PIN diode designed for low-distortion switching and attenuation in HF–S-band systems. It features 400 V reverse voltage rating, 0.5 Ω typical series resistance at 100 MHz, >5 µs carrier lifetime, and 3 pF capacitance at 100 V/1 MHz-enabling precise RF power control in antenna couplers and phase shifters.

For engineers reviewing the UM4002B datasheet, UM4002B pinout, UM4002B application, or UM4002B equivalent, key selection criteria include reverse voltage margin, thermal path efficiency in stud-mount configurations, RF linearity under high peak power, and compatibility with automatic insertion equipment for high-volume microwave module assembly.

Technical Context

The UM4002B employs a non-cavity, thick I-region structure optimized for long carrier lifetime (>5 µs) and low distortion across HF to S-band frequencies. Its design enables high RF voltage handling beyond applied reverse bias and supports stable operation under pulsed megawatt-level conditions in duplexers.

Thermally matched configuration and low 0 V-bias capacitance (≤3 pF) and conductance ensure minimal signal perturbation during RF switching. The device operates with low bias current due to high charge storage, reducing driver circuit complexity in high-isolation switch designs.

Key Specifications

Pinout & Package

UM4002B is housed in Style "B" isolated stud-mount package with two terminals: anode and cathode. Thermal path is optimized via direct stud-to-chip interface for high-power RF duty cycles.

Key Features

Applications

Equivalent & Alternatives

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

Compared with UM4002B, UM4902B offers higher thermal capacity for CW-heavy applications, while UMX4002B delivers identical RF performance with lead-free process compatibility-neither is pin-compatible by mechanical footprint alone, as Style "B" variants require verification of stud-mount hole pattern and torque spec per application.

Availability

UM4002B is available at Aetrix Electronics and suitable for antenna phase shifters, high-power duplexers, RF filter tuners, and cavity coupler switches requiring stable component supply across aerospace, defense, and telecom infrastructure programs.

Supply support for UM4002B 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) specializes in high-reliability analog and RF semiconductors for aerospace, defense, and industrial applications.

The UM4000/UM4900 series was engineered specifically for high-power microwave switching in mission-critical radar and comms systems where thermal robustness and RF linearity are non-negotiable.

FAQ

What is the maximum reverse voltage rating for UM4002B?

The UM4002B has a reverse voltage rating of 400 V at 10 µA leakage current. This rating allows it to safely handle RF peak voltages significantly exceeding the applied DC reverse bias in S-band phase shifters and duplexers. Operation beyond 400 V risks irreversible junction breakdown and must be avoided in all UM4002B applications.

Does UM4002B require a heatsink in typical RF switch applications?

Yes, UM4002B requires a thermally conductive stud mount to a heatsink or chassis. Its 25 W power dissipation rating is specified at 25°C stud temperature; without adequate heat sinking, junction temperature rise can exceed safe limits even at moderate RF duty cycles. Thermal impedance data confirms active cooling is essential for sustained operation above 5 W average power.

Is UM4002B compatible with lead-free reflow soldering processes?

No-standard UM4002B uses Sn/Pb finish. For lead-free assembly, specify UMX4002B, which features RoHS-compliant matte tin plating and identical electrical/thermal performance. Substituting standard UM4002B into Pb-free reflow profiles risks solder joint voiding and intermetallic degradation due to incompatible melting characteristics.

How does carrier lifetime affect UM4002B's RF switching performance?

UM4002B's >5 µs carrier lifetime enables high RF current control with low DC bias current, reducing driver power requirements. However, it also limits switching speed-transient response is governed by minority carrier decay, making UM4002B unsuitable for nanosecond-scale modulation but ideal for µs-to-ms RF gating in radar T/R modules and tunable filters.

Can UM4002B be used in surface-mount designs?

No-UM4002B is exclusively offered in Style "B", a stud-mounted metal package requiring mechanical fastening and thermal interface to a heatsink. Surface-mount variants exist in the same family (e.g., UM4002SM), but UM4002B itself has no SMT footprint or reflow-compatible terminations.