Energy-Saving Low-Noise LDO Regulator from STMicroelectronics


The STMicroelectronics LDO40L 400mA low-dropout linear regulator delivers quiet and efficient power for always-on automotive modules and noise-sensitive loads.

With 45µA quiescent current, the AEC-Q100 qualified  LDO40L reduces the demand on vehicle batteries to run loads such as body and interior functions that are active when the ignition is off. In addition, the device can be disabled to achieve a very-low shutdown current of only 1µA.


The internal circuity operates from an input voltage as low as 3.5V and combined with the extremely low dropout voltage of 36mV at 100mA load, or 140mV at full load, they enable the LDO40L to maintain power to the load as the input dips during cold cranking.

In addition to powering automotive body-control modules, instruments and clusters, and LED lighting, the LDO40L also ensures stable, high-quality DC for industrial controls and building- or home-automation applications. Output noise is just 20µV, power-supply rejection ratio (PSRR) 70dB @1kHz, and protection features including current limit and thermal shutdown are built-in.


  • Wide input voltage operating range up to 38 V
  • Output current up to 400 mA
  • Output voltage options: Adj from 2.5 V and fixed, 3.0, 3.3, 5.0 and 8.5 V
  • Output voltage accuracy:
    • ± 1% typ. @ 25 °C
    • ± 3% (including line, load and temperature variation)
  • Very low noise: 20 µVRMS/VOUT
  • Protection features: current limitation, thermal shutdown
High Isolation Switch Supports 5G and Public Safety Infrastructure


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