UM4901C

RF Diode Overview

The UM4901C is a high power PIN diode from the UM4900 series, manufactured by Microchip Technology. It features a silicon construction with a long carrier lifetime exceeding 5 µs and thick I-regions. The device has a reverse voltage rating of 100 V at 10 uA leakage current. Electrical parameters include a typical forward voltage of 1.0 V at 100 mA, 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 up to 37.5 W depending on the thermal path.

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 devices.
• 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 and megawatt peak-power duplexers.
• Antenna selectors and couplers where inductance and capacitance elements are switched in filter or cavity networks.

RF Diode Procurement Notes

Verify the specific package style suffix (e.g., C, D) required for the application, as the base model number indicates only the electrical characteristics. Confirm RoHS compliance requirements; standard versions use Sn/Pb finish, while RoHS compliant units require the UMX prefix. Check datasheet specifications for absolute maximum ratings under intended operating conditions.

RF Diode Selection Notes

Select the UM4901C when high power handling and low distortion switching are required in HF to S band applications. Choose this over the UM4000 series if higher power dissipation is needed due to the superior thermal path. Ensure the selected package style matches the mounting constraints and thermal management strategy of the system design.

RF Diode Part Context

The UM4901C belongs to the UM4900 series of high power PIN diodes. This series is electrically equivalent to the UM4000 series but offers higher power ratings. The UM4900 series is designed for robust performance in demanding RF environments, having been qualified in high power applications with thousands of hours of proven operation.

RF Diode Replacement Considerations

The UM4001C is an electrically equivalent alternative within the UM4000 series. Note that the UM4001C has lower power dissipation ratings due to a longer thermal path. For RoHS compliance, consider the UMX4901C variant which uses a matte tin finish instead of the standard Sn/Pb finish.