178001 Wurth

Reference Design Note 3 MagI C Power Modules 3 DNS001 MagI C LED Driver 1. Introduction The rated power and thus the lumen of LEDs on the lighting market is constantly increasing. High power LEDs require a current of 700 mA, 1 A or more. Allthough high output currents are commonly supported by voltage regulated modules, high current LED driver modules are difficult to find in the market. 3 3 The MagI C LED Driver 178001 demonstrates how a MagI C Power Module can be used for applications that require a current source for high power LEDs or for battery charging. This reference design is capable of driving up to 1.5 A of output current using a voltage regulated module and an external secondary regulation loop to establish current regulation. The external loop regulates a DC output current, which results in a constant photon output from the LED. An adjustable output current limit can be set from 10mA to 1.5A, turning the module into a constant current source. Output currents can have arbitrary waveforms, allowing the imitation of the flickering light of a candle with LEDs or light bulbs. Batteries can be charged with a DC current or with a defined charging current waveform if a digital to analog converter or 3 a PWM output of a microcontroller is used to adjust the output current of the MagI C LED Driver. 3 During the development of a customers prototype, the MagI C LED Driver can be connected by wires or via SMD Footprint to the prototype PCB until the LED Driver is merged into the customers PCB for the final product. Compared to other solutions with pulsed LED current, this solution is less harmful to the eyes due to the constant photon flow, allowing the pupil opening to be the proper size for the light intensity emitted. Depending on the LED flux voltage, up to 4 white high power LEDs can be connected in series - or up to 6 color high power LEDs. 3 Figure 1. MagI C LED Driver Order Code 178001 VIN LED + DIM 3 MagI C ENABLE LED Driver POWERGOOD GND LED - Figure 2. Typical Circuit Diagram DNS002 V2.0 Roland Kratz - August 2019 Page 1/10 Copyright Wrth Elektronik eiSos GmbH & Co. KG Reference Design Note 3 MagI C Power Modules 3 DNS001 MagI C LED Driver 2. Specifications Electrical Specifications Features Input Voltage Range 7V 36V PWM or Voltage Dimming Input Voltage Transients Max. 45V Enable/Disable Function Output Voltage Range 0V VIN Power Good Signal Output Current Limit 10mA 1.5A Allows SMD Pick & Place Output Current Ripple 10mApp typ. Maximum Output Power 22.5W Switching Frequency 400kHz Operating Ambient Temperature Range -40C to +85C DIM Voltage 0V 5V 3. Functional Diagram Power Module L 1 T 1 T2 C C R IN Controller IC OUT LOAD R s Error Amplifier Adj. Current Set Value Figure 3. Functional Diagram The error amplifier compares the set value of the output current to its actual value measured at R and adjusts the voltage S at the power modules feedback pin maintaining the set output current value. DNS002 V2.0 Roland Kratz - August 2019 Page 2/10 Copyright Wrth Elektronik eiSos GmbH & Co. KG Feedback