L4945

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Overview

The L4945 is a monolithic integrated circuit in Versawatt (TO-220) package designed to provide stabilized 5V supply for automotive and industrial systems. It features very low dropout voltage of 0.75V max at 500mA output current over the full temperature range (-40°C to 125°C). The device operates with an input voltage range of 6V to 26V, with transient protection up to 80V. Key protections include reverse voltage (-18V), short circuit, thermal shutdown, and load dump immunity.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Feature Summary

• Very low dropout voltage ensures correct operation during automotive cranking phases when battery voltage drops as low as 6V.
• Integrated comprehensive protection circuits against dangerous overvoltages, reverse polarity, and short circuits present on vehicle battery rails.
• Low startup current achieved through internal antisaturation circuitry that drastically reduces initial current peaks.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Applications

• Automotive electronic systems requiring stable power during engine cranking
• Industrial electronic systems needing robust voltage regulation
• Microcomputer controlled systems exposed to harsh electrical environments

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Procurement Notes

Verify component status as the datasheet indicates this product may be obsolete or under evaluation. Confirm availability through authorized STMicroelectronics distributors. Ensure the Versawatt TO-220 package matches your thermal and mechanical requirements. Check for updated replacement parts if this specific ordering number is no longer in active production.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Selection Notes

Select the L4945 for applications requiring precise 5V regulation with minimal voltage drop under high load conditions. The lateral PNP power stage offers superior dropout performance compared to standard NPN regulators. Ensure external compensation capacitor meets minimum 47μF requirement with ESR less than 3Ω for system stability. Consider thermal resistance characteristics for heat dissipation in enclosed spaces.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Part Context

The L4945 belongs to STMicroelectronics' family of very low drop voltage regulators specifically engineered for demanding automotive environments. Unlike general-purpose regulators, it incorporates specialized protection against automotive-specific transients like load dump and field decay. The device utilizes advanced lateral PNP technology to achieve its low dropout characteristics while maintaining high precision output voltage across wide temperature variations.

Voltage Regulators - Linear, Low Drop Out (LDO) Regulators Replacement Considerations

Check STMicroelectronics documentation for direct replacements if L4945 is obsolete. Similar low-dropout 5V regulators in TO-220 packages may require verification of pin compatibility and protection feature equivalence. Evaluate alternative part numbers within the same regulatory family for functional substitution.