Configurable LDOs provide diagnostics for automotive functional safety
Eight selectable fixed-output voltages, diagnostic features for functional safety and high thermal performance are integrated in the L99VR01 AEC-Q100-qualified low-dropout (LDO) linear voltage regulators by STMicroelectronics. It simplifies system design and ease inventory management for multiple automotive applications, says ST.
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 5.0V more accurately than with an external voltage divider using three external selection pins. The output is within ±two per cent of the nominal value.
ST offers two device versions. The L99VR01S comes in a standard SO-8 package with enable and reset pins. There are also safety features such as fast output discharge, under-voltage lockout (UVLO), thermal shutdown, and short-circuit protection. The quiescent current is reduced to 1 microA when disabled and the regulator operates from -40 to +150 degrees C.
The second version is the L99VR01J in PowerSSO-12. This 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 degrees C.
By integrating output over-voltage monitoring, both 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.(Supporting documentation is available on request.)
Both also 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 the L99VR01S and the L99VR01J are in production now.
