LDO40LPU33RY

Overview

The LDO40LPU33RY is a fixed-output linear regulator from the STMicroelectronics LDO40L series, delivering a nominal 3.3 V output with a maximum current of 400 mA. It operates within an input voltage range of 3.5 V to 38 V and features a low quiescent current of typically 45 µA at no load. The device provides high power supply rejection ratio (PSRR) of 70 dB at 1 kHz and maintains an ultra-low dropout voltage of 140 mV at full load. Packaged in a compact 6-DFN (3x3 mm) format with wettable flanks, it is AEC-Q100 Grade 1 qualified for automotive environments.

Feature Summary

• AEC-Q100 Grade 1 qualification for severe automotive environments
• Ultra-low quiescent current suitable for always-on battery applications
• Integrated current limit and thermal shutdown protection
• Wettable flank DFN6 package for enhanced solder joint inspection

Applications

• Automotive body control modules
• Instruments and clusters
• Automotive LED lighting systems

Procurement Notes

Verify the specific ordering code matches the required output voltage and package variant. Confirm that the application design accounts for the minimum input voltage requirements relative to the dropout voltage at the expected load current. Ensure the enable pin is properly biased and not left floating to prevent unintended operation or excessive standby current consumption.

Selection Notes

Select this component when a fixed 3.3 V rail is needed with high input voltage tolerance up to 38 V. The low quiescent current makes it ideal for systems requiring minimal power drain during ignition-off states. Consider the thermal resistance characteristics of the DFN6 package for heat dissipation calculations under maximum load conditions.

Part Context

This part belongs to the LDO40L family of low-dropout regulators designed for harsh automotive and industrial environments. The series offers various fixed output voltages and an adjustable version, all sharing the same 400 mA capability and robust protection features. The family is characterized by its ability to start up at low input voltages and maintain regulation across wide temperature ranges.

Replacement Considerations

Other members of the LDO40L family, such as LDO40LPU50RY (5.0 V) or LDO40LPURY (Adjustable), share identical pinouts and electrical characteristics except for the output voltage setting. Direct substitution requires verifying that the target circuit does not depend on the specific 3.3 V output level.

FAQ

How should the VSENSE pin be connected?

The VSENSE pin must not be left floating. For standard applications, it should be directly shorted to the VOUT pin. In remote-sensing configurations, it can be connected to the load.

What are the stability requirements for external capacitors?

The device requires a minimum of 1 µF on both the input and output ports. Good quality ceramic capacitors (X5R/X7R) are recommended. The output capacitance has no upper limit provided the ESR remains within the stable region defined in the datasheet.