LD3985G28R

Overview

The LD3985G28R is a fixed-output linear voltage regulator manufactured by STMicroelectronics. It provides a stable 2.8V output with a maximum continuous current of 150mA. The device operates from an input voltage range of 2.5V to 6V and features an ultra-low dropout voltage, typically 60mV at full load. Key electrical parameters include a quiescent current of 85µA (typical) and a shutdown current below 1.5µA. Power supply rejection ratio (PSRR) exceeds 60dB at 1kHz. The component is housed in a compact SOT-23-5 package and supports operation across a temperature range of -40°C to +125°C.

Feature Summary

• Ultra-low dropout voltage design compatible with low ESR ceramic capacitors
• Logic-controlled electronic shutdown function for standby power management
• Low noise output performance suitable for sensitive analog circuits
• Integrated thermal and current limiting protection mechanisms

Applications

• Battery-powered mobile phones and wireless systems
• Personal digital assistants (PDAs) and palmtop computers
• Portable audio devices such as personal stereos
• Camcorders and camera modules requiring low noise regulation

Procurement Notes

Verify the specific suffix 'G' against official STMicroelectronics documentation to confirm RoHS compliance status and exact pinout configuration. Ensure the selected package variant matches the required PCB footprint. Confirm availability status as older LDO families may have limited production runs or obsolescence notices.

Selection Notes

Select this component when designing battery-operated systems requiring minimal voltage drop between input and output. The low quiescent current extends battery life during active operation, while the shutdown feature aids in reducing standby consumption. Verify that the application load does not exceed the 150mA limit and that input voltage remains within the specified 2.5V to 6V window.

Part Context

This part belongs to the LD3985 family of ultra-low-dropout regulators designed for low-power applications. It shares architectural similarities with the LD2985 but offers optimized performance for modern portable electronics. The series is characterized by its ability to maintain stability with small ceramic output capacitors, simplifying board layout and reducing overall component count in space-constrained designs.

Replacement Considerations

Direct substitutes include the LD3985M28R and LD3985S28R, which offer identical electrical specifications but differ in packaging options such as MSOP or DFN. Cross-reference with the LD2985 series if a different pinout is acceptable, noting potential differences in quiescent current profiles.