L78L33CD

Overview

The L78L33CD is a three-terminal positive linear voltage regulator from the L78L series, manufactured by STMicroelectronics. It provides a fixed output voltage of 3.3 V with an output current capability up to 100 mA. The device features internal thermal overload protection and short-circuit protection. It operates within a junction temperature range of 0 °C to 125 °C for the C grade. The maximum DC input voltage is 30 V for this output voltage level. The quiescent current is typically 6 mA at 25 °C. Line regulation is specified at 150 mV (VI = 5.3 to 20 V) and load regulation at 60 mV (IO = 1 to 100 mA). Dropout voltage is typically 1.7 V. Supply voltage rejection ratio is typically 49 dB at 120 Hz.

Feature Summary

• Internal current limiting and thermal shutdown mechanisms ensure robust operation under fault conditions.
• Designed as a fixed voltage regulator suitable for local or on-card regulation applications.
• Requires no external components for basic operation, simplifying circuit design.

Applications

• Local or on-card voltage regulation
• Replacement for Zener diode and resistor combinations
• Power supply sections for electronic equipment

Procurement Notes

Verify the specific package type required for the application, as the L78L33 part number exists in multiple packages including TO-92, SO-8, and SOT-89. Confirm that the 'CD' suffix corresponds to the desired package and tolerance variant by checking the manufacturer's official ordering information table. Ensure the selected component meets the thermal requirements for the intended operating environment.

Selection Notes

Select this component when a fixed 3.3 V output is needed with moderate current demands up to 100 mA. Consider the thermal resistance characteristics of the chosen package if high power dissipation is expected. Verify that the input voltage remains within the 30 V maximum limit. Compare line and load regulation specifications against system requirements to ensure adequate stability.

Part Context

The L78L33CD belongs to the L78L series of three-terminal positive regulators. This series is designed for general-purpose voltage regulation tasks. The 'C' designation indicates an 8% output voltage tolerance. The 'D' suffix typically denotes the SO-8 surface-mount package variant in STMicroelectronics nomenclature for this series.

Replacement Considerations

Compatible replacements include other L78L33 variants from different manufacturers offering similar electrical characteristics. Cross-reference package pinouts carefully when substituting between through-hole and surface-mount versions. Verify thermal performance matches the original design constraints.