UM4902C

RF Diode Overview

The UM4902C is a high-power silicon PIN diode from the UM4900 series, designed for HF through S-band applications. It features a 200 V reverse voltage rating at 10 uA leakage current and a typical carrier lifetime of 5 to 10 µs. The device exhibits a maximum series resistance of 0.5 Ω at 100 MHz and a typical capacitance of 3 pF at 100 V reverse bias. Power dissipation reaches 37.5 W with a thermal resistance of 4 °C/W under stud temperature conditions. These specifications support its use in high RF power switching environments.

RF Diode Feature Summary

• High charge storage and long carrier lifetime enable control of high RF levels with relatively low bias current.
• Peak RF voltages can be handled well in excess of applied reverse bias voltage.
• Shorter thermal path between chip and package provides higher power ratings compared to electrically equivalent UM4000 series.
• Non-cavity design with low capacitance and conductance at zero bias.

RF Diode Applications

• Low distortion switches and attenuators in HF through S band frequencies
• High power UHF phase shifters
• Megawatt peak-power duplexers
• Antenna selectors and couplers

RF Diode Procurement Notes

Verify the specific package style (e.g., Stud or Surface Mount) required for the application, as the UM4902C designation refers to the electrical characteristics while suffixes indicate mechanical form. Confirm RoHS compliance status if lead-free finish is mandatory, noting that standard versions may utilize Sn/Pb finishes unless specified otherwise by the manufacturer's current production data.

RF Diode Selection Notes

Select the UM4902C when operation requires handling peak RF voltages exceeding the reverse bias voltage and managing high power levels within HF to S-band ranges. The UM4900 series offers superior thermal performance over the UM4000 series due to its shorter thermal path. Ensure the chosen package style aligns with the available mounting options and thermal management requirements of the system design.

RF Diode Part Context

The UM4902C belongs to the UM4900 series of high-power PIN diodes manufactured by Microsemi. This series is characterized by thick I-regions and long carrier lifetimes, distinguishing it from lower-power variants. The UM4900 series is electrically equivalent to the UM4000 series but provides enhanced power dissipation capabilities through optimized thermal design.

RF Diode Replacement Considerations

The UM4002C is an electrically equivalent alternative within the UM4000 series. However, it possesses lower power ratings due to a longer thermal path between the chip and package. Substitution requires verification of thermal management adequacy for the specific application power levels.