The L99VR02J is our first programmable linear voltage regulator for the automotive industry to deliver up to 500 mA. By setting its SELx pin, engineers can choose from a wide range of output voltages (0.8 V; 1.2 V; 1.5 V; 1.8 V; 2.5 V; 2.8 V; 3.3 V, or 5 V), thus making it one of the most flexible LDOs in its category. Consequently, teams use it for numerous designs, such as seat and door applications, sensors and lighting, heating and cooling, and more. Thanks to its wide range of output voltage, it can power all sorts of components, from ultra-low MCUs and MEMS to more demanding devices.
3 questions at the heart of every project
How to simplify designs?
The L99VR02J draws much of its inspiration from the L99VR01, which offers the same programmability but supports up to 200 mA. Traditionally, competing devices will have a significantly smaller number of output voltages available, and engineers must configure their system by using external resistors. As a result, the PCB layout increases in complexity, and teams must be mindful of the resistor’s tolerances to account for the customary ±2% variations in output voltages. The L99VR02J and the L99VR01 remove all this complexity by providing a user-configurable pin, thus enabling vastly more granularity in the choice of output voltages and a much simpler approach.
How to tailor to more demanding applications?
We provided two packages when we launched the L99VR01 a few years ago. The L99VR01S used an SO-8 housing (6 mm x 4.90 mm), while the L99VR01J adopted the PowerSSO-12 package (5.8 mm x 4.8 mm) for systems with more significant thermal requirements since it runs cooler. The latter was quite popular as customers shared their desire to use the device in increasingly more powerful setups. Consequently, we are answering this need by launching a device that can support more than twice the current of the previous model. We are also working on the L99VR02XP, which would support 2 x 250 mA, and will update this blog post once the device is available.
How to improve energy efficiency?
The advent of electric vehicles pushes designers to lower voltages as much as possible to save battery life. For instance, the industry is increasingly adopting microcontrollers with a lower input voltage, among other things. Hence, while it was essential to ship a device that could support a higher current, we kept the same low-voltage settings at the request of our customers. Similarly, we ensured that the L99VR02J had the same quiescent current of less than 1 µA as its predecessor. Indeed, as teams constantly seek power savings, being able to enter such a low-power mode instantly helps further the overall efficiency.
2 considerations before getting started
How to leverage the ST ecosystem?
The shared DNA between the L99VR01 and L99VR02J means that moving from one to the other is relatively straightforward. Since they are pin-to-pin compatible and use very similar passive components, engineers can reuse a significant portion of their designs. Moreover, ST also provides a development board, the AEK-POW-LDOV02J, which comes with free-to-use schematics, thus further facilitating the design process. We also updated AutoDevKit to support the new board. Developers can, therefore, experiment with the reconfigurability of the device and its numerous other features, such as its watchdog capability and protection mechanisms. There’s even a user manual that details how to code test applications for the board.
How to take advantage of all the features of the L99VR02J faster?
It is common for automotive-grade LDOs to have an expansive feature list. For instance, a watchdog ensures there’s a constant connection with the MCU, which is necessary when working on safety-critical applications. Similarly, having a pin provide thermal and over-voltage diagnostic is essential to prevent severe damage. However, thanks to AutoDevKit, taking advantage of all these features is straightforward. Indeed, the user manual for the AEK-POW-LDOV02J board shows how a single function can detect warning events in case the MCU is disconnected or internal protection is activated. We even provide sample code to hasten the prototyping phase.
