LD2981CM18TR

Overview

The LD2981CM18TR is a fixed-output low-dropout (LDO) linear voltage regulator manufactured by STMicroelectronics. It provides a regulated output voltage of 1.8 V with a maximum continuous output current capability of 100 mA. The device operates within an input voltage range up to 16 V and features a typical dropout voltage of 375 mV at full load. Quiescent current is specified at approximately 80 µA in active mode, reducing to less than 1 µA when the inhibit pin is activated for shutdown. The component is housed in a surface-mount SOT-23-5 package and is rated for operation across an extended temperature range from -40 °C to +125 °C.

Feature Summary

• Ultra-low quiescent current consumption with logic-controlled electronic shutdown via inhibit pin
• Designed for stability with low ESR ceramic output capacitors
• Integrated internal protection against thermal overload and short-circuit conditions

Applications

• Battery-powered portable electronics requiring low power standby modes
• Cellular phones and personal digital assistants (PDAs)
• Low noise analog circuit supply regulation

Procurement Notes

Verify the specific suffix 'M18' confirms the 1.8 V fixed output voltage variant. Confirm the 'TR' designation indicates tape-and-reel packaging suitable for automated assembly. Ensure the SOT-23-5 footprint matches the target PCB layout. Cross-reference the manufacturer datasheet for absolute maximum ratings to prevent overvoltage damage during integration.

Selection Notes

Select this component when a stable 1.8 V rail is required with minimal static power draw. The LDO topology is preferred over switching regulators for applications sensitive to electromagnetic interference due to its low output noise. Verify that the input-to-output voltage differential remains within the specified dropout limits to maintain regulation under all load conditions.

Part Context

This part belongs to the LD2981 family of ultra-low drop voltage regulators. The series is characterized by high performance in low-power environments, offering fast dynamic response to line and load changes. Other variants in the family provide different fixed output voltages such as 2.5 V, 3.0 V, 3.3 V, and 5.0 V, sharing identical pinouts and protection features.

Replacement Considerations

Compatible substitutes include other 1.8 V LDOs in SOT-23-5 packages with similar 100 mA current ratings. Verify pin compatibility and thermal characteristics before substitution. Check if alternative parts support the same ceramic capacitor stability requirements.