Power

Automotive low-dropout regulators for functional safety

13th July 2021
Alex Lynn

With eight selectable fixed-output voltages, diagnostic features for functional safety, and high thermal performance, STMicroelectronics’ L99VR01 AEC-Q100 qualified low-dropout linear voltage regulators simplify system design and ease inventory management for multiple automotive applications.

The regulators supply up to 200mA for powering loads such as body modules, junction boxes, instrument clusters, sunroof controllers, keyless-entry controllers, and sensors. The output voltage can be set to 0.8, 1.2, 1.5, 1.8, 2.5, 2.8, 3.3, or 5V more accurately than with an external voltage divider using three external selection pins. The output is within ±2% of the nominal value.

Two device versions are available. The L99VR01S comes in a standard SO-8 package with Enable and Reset pins as well as safety features such as fast output discharge, under-voltage lockout (UVLO), thermal shutdown, and short-circuit protection. The quiescent current is reduced to 1μA when disabled and the regulator operates from -40 to +150°C.

The L99VR01J in PowerSSO-12 additionally allows programming the short-circuit current limit, provides thermal warning and output-overvoltage status indications, and contains a programmable watchdog that checks for correct operation of the host microcontroller. The L99VR01J also has a wider operating junction temperature range, from -40 to 175°C.

By integrating output overvoltage monitoring, the new regulators can provide constant load protection. The diagnostic features ease the design of functional-safety related applications, helping users achieve the required ISO 26262 ASIL value. Appropriate supporting documentation is available on request.

Both variants feature a wide input-voltage range, from 2.15 to 28V, allowing use in applications connected directly to the battery voltage, VBAT, or for post-regulation to convert an already regulated voltage. The inputs are 40V tolerant to withstand load dump.

Both variants are in production now. Pricing for orders of 1,000 pieces starts from $0.28 for the L99VR01S and from $0.35 for the L99VR01J.

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