Low-noise LDO regulator powers automotives and smart automation

For always-on automotive modules and noise-sensitive loads, the LDO40L 400mA low-dropout (LDO) linear regulator delivers quiet and efficient power, says STMicroelectronics.

The AEC-Q100 qualified LDO40L has 45 microA quiescent current and reduces the demand on vehicle batteries to run loads such as body and interior functions that are active when the ignition is off. The LDO40L can be disabled to achieve a very-low shutdown current of only one microA.

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

The LDO40L powers automotive body-control modules, instruments and clusters, and LED lighting, and ensures stable DC for industrial controls and building- or home-automation applications. Output noise is just 20 microV, power-supply rejection ratio (PSRR) 70dB at 1kHz, and protection features including current limit and thermal shutdown are built-in.

There is a choice of fixed 3.0, 3.3, 5.0 or 8.5V output voltage, regulated within ± three per cent including line, load and temperature variation. Only two capacitors are needed to complete the application circuit. An adjustable-output version is also available, which allows designers to set an output voltage down to 2.5V minimum using an external resistor divider.

All versions are housed in a 3.0 x 3.0mm DFN6 package with wettable flanks, which is smaller than the DPAK outline of typical competing devices yet maintains high thermal performance and excellent reliability in relation to heatsink size.

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