Open LED Protection for LED Strings

 LEDs are fragile solid-state devices. An LED is essentially a diode, structured as a P-N junction that emits light when forward-biased. One of the major causes of an electrical open circuit in an LED is thermomechanical stress on the wire bonds. Other causes of LED open circuits are electrostatic discharge (ESD) events or surges induced by nearby lightning events. These threats are especially high in outdoor applications. Devices such as MOVs, fuses, and TVS diodes are essential for a circuit protection strategy because they can prevent transients and surges from damaging delicate LEDs. However, none of these traditional circuit protection devices can prevent an entire string of LEDs from going out if a single LED fails.  

An open LED protector can be connected in parallel with each LED in a string; it will shunt current around an open-failed LED to keep the rest of the string lit. When the LED fails, it becomes open-circuit, and the open LED protector goes into conduction, limiting its voltage drop to about 1.3V and keeping the rest of the string operating.

Voltage-Tracking LDO With 4-mV Tracking Tolerance

 The voltage-tracking low dropout regulator (LDO) is commonly used in automotive off-board sensors and small current off-the-board modules due to its off-board protection and high voltage-tracking accuracy advantages. The output of the device is precisely regulated by the ADJ reference voltage.

To obtain accurate sensor readings, a power supply always requires better stability and accuracy. This device offers a 4-mV ultralow tracking tolerance between the ADJ and FB pins across temperatures, meeting the voltage accuracy requirements for off-board modules.

Below is a recommended PCB layout sample by TI for your reference

Altium Designer : Solving the Component Management Challenge with Alticve BOM

 

ActiveBOM offers a robust Bill of Materials management editor, leveraging Altium's advanced part-information aggregation technologies to effortlessly tackle the component selection challenge.

What is the difference between lux and lumens?

It's important to understand the distinction between Lux and Lumens when designing lighting products. The main difference can be summarized as follows:

- Lux measures illuminance, which is the total amount of light that falls on a surface.

- Lumens measure luminous flux, which is the total amount of light emitted in all directions.

Information Reference: 

Voltage controlled Current Source Circuit

 

This circuit effectively controls the output current flow. The reference voltage V1 can be set to the desired output current; for instance, V1=700 mV sets the output current to 670 mA.