LD2981CU18TR

Overview

The LD2981CU18TR is a fixed-output low-dropout (LDO) linear voltage regulator manufactured by STMicroelectronics. It provides a fixed output voltage of 1.8 V with a maximum continuous output current of 100 mA. The device supports an input voltage range up to 16 V and operates within a junction temperature range of -40 °C to +125 °C. Key electrical characteristics include a typical quiescent current of 80 µA in active mode, a maximum dropout voltage of 375 mV at full load, and internal protection against overcurrent and thermal overload.

Feature Summary

• Logic-controlled electronic shutdown via inhibit pin for standby power management
• Ultra-low dropout voltage operation suitable for battery-powered systems
• Designed for stability with low ESR ceramic output capacitors
• Integrated overcurrent and thermal limit protection functions

Applications

• Portable cellular phones and mobile communication devices
• Personal digital assistants (PDA) and handheld computers
• Battery-powered consumer electronics requiring low noise regulation
• Point-of-load regulation in laptop and palmtop systems

Procurement Notes

Verify the specific suffix 'CU' indicates the SOT-89-3 package configuration when sourcing replacements. Confirm that the '18' designation strictly corresponds to the 1.8 V fixed output voltage variant. Ensure compatibility with low ESR ceramic capacitors as specified in the official datasheet to maintain loop stability. Check RoHS compliance status for the specific manufacturing batch prior to integration.

Selection Notes

Select this component when a fixed 1.8 V rail is required with minimal voltage headroom between input and output. The low quiescent current makes it suitable for extending battery life in portable applications. Consider the SOT-89-3 package for compact surface-mount designs where thermal dissipation requirements are moderate. Verify that the load current does not exceed the 100 mA continuous rating under worst-case thermal conditions.

Part Context

This part belongs to the LD2981 family of ultra-low drop voltage regulators from STMicroelectronics. The family offers various fixed output voltages including 2.5 V, 3.0 V, 3.3 V, and 5.0 V. The CU suffix typically denotes the SOT-89-3 surface-mount package variant, distinguishing it from the SOT-23-5L package used in other versions like the CM series. All variants share similar electrical performance profiles regarding dropout voltage and shutdown logic.

Replacement Considerations

LD2981CM18TR: Identical electrical specifications but utilizes the SOT-23-5L package instead of SOT-89-3. Requires footprint adaptation during PCB design changes.