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Questions tagged [led-driver]

An LED driver is a self-contained power supply that controls the amount of current and voltage supplied to an LED light. An LED constant current driver monitors the loop current of each LED and automatically adjusts the generated DC voltage output to the minimum value needed to produce the highest forward voltage. As mains power is AC and Light Emitting Diodes run on DC, this current needs to be converted by a rectifier

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31 views

Can I use a 555 PWM signal to control

I want to use a 555 PWM signal to control a motor. I also want represented the speed of the motor with an LED graph using a LM3914 led driver. Can I use a digital signal to control the LM3914 ...
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1answer
22 views

What could be causing an unreliable output for 3 different IS31FL3731 chips

I have a board that uses the Adafruit breakout of the IS31FL3731 to control 81 illuminated switches. I have some code that runs on an Arduino that should turn all the lights on, but only about half ...
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1answer
42 views

Multiplexed LED column driver MOSFET doesn't fully turn off without a resistor parallel to the LEDS

I have a board with a 16x10 led matrix. The columns are switched with DMG9933 Dual P mosfets. The rows are driven with a constant current led driver ST STP16CPC26 (similar to TI TLC5956) I noticed ...
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3answers
78 views

LED brightness stability issues - how to fix?

I am performing an imaging experiment in which LED stability is critical. I use 2-3 red LEDs to illuminate a surface while imaging that surface. In each LED circuit, I use a constant-voltage ...
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1answer
40 views

High current, high frequency IC PWM switching with MOSFETs

I'm designing a circuit for an automotive application (chassis ground) that has a number of MOSFET outputs to drive large LED arrays and smaller motors (application tends to favour non inductive modes,...
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1answer
54 views

LED driver putting out more voltage than rated?

The Background I bought a 200W magnetic LED driver with hopes of replacing the 40W Philips-supplied driver that came with my set of Hue Lily outdoor lights. Each fixture requires 8W at 24v. This new ...
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37 views

SOT23-3 part identification - marking 12A1G

I have a SOT23-3 device with marking 12A1G. It is used to power Wifi module in a smart dimmable LED driver. Can you share details of this chip? It is used as a control with integrated MOSFET in a non-...
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2answers
77 views

Why are flickering LED driver circuits cheaper than flicker-free circuits?

Many low cost LED fixtures have a 2X line frequency flicker. Since flicker free switching LED power supplies are not difficult to design, I assume that flickering drivers are cheaper than flicker ...
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1answer
44 views

Constant Current Output driver connected to 2 COB LEDs - is the hookup valid?

I have a lamp with this hookup. Can someone confirm whether the electrical specs match up such that these can be connected in this way. ld009d-cu03036-m9 - MagTech Constant Current 24-36v output ...
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1answer
22 views

MP3301 LED Driver RC Filter Calculation for PWM

I am looking at the datasheet for the MPS MP3301 Step-up LED Driver. I have two questions about the "PWM Dimming" section on page 8. The datasheet says for PWM frequencies > 1kHz, use an RC filter ...
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2answers
58 views

LEDs sharing negative output from driver issue

I am having an issue with the above circuit when LED DRIVER B has 0 PWM and LED driver A is being driven by a signal driver B is supposed to be off but the leds from BANK B are still lit dim. I ...
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1answer
39 views

Deciphering which COB LED used in a circuit [closed]

I have two lamps with identical LED circuits. The lamps sometimes blink when turning on. One of the lamps already has a blown COB LED. I suspect the wiring was done wrong. I've opened it up, but I ...
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2answers
482 views

How to reduce LED flash rate (frequency) [closed]

I have purchased an LED flasher circuit from Ebay (see jpg) for use on a model plane, but the flash rate on the circuit is much too fast, about 4 flashes a second. I am trying to achieve 1 or 2 ...
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2answers
46 views

Multiplexing high current connections?

Noob question here. Currently I'm using a darlington transistor array to drive about 14 IR leds. I want to be use a CD74HC4067 multiplexer to simplify and shrink things up a bit. The IR led's I'm ...
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1answer
55 views

Power multiple parts of one project from one wall wart

I'm building a project with a high-power 10W RGB LED controlled by PWM from a microcontroller. Right now I'm using a wall wart to power the LED, and powering the MCU through my computer's USB. My ...
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3answers
99 views

Boost LED driver output spikes

I designed a boost LED driver based on TPS92691. It drives 56V 5A COB LED from 22-50V input. It works ok. Oscilloscope shows small spikes on input (100mV), but large spikes on output (3V). The spikes ...
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1answer
38 views

driver for IR led board

I'm installing a cheap IR led board like this. Do they need any kind of driver? Or just a 12V power supply switched with a relay (to power on/off) If so, is there any kind of consideration I need ...
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1answer
85 views

LED-drivers FAN5331 and FAN5333

I have a question about the following LED drivers: FAN5331, datasheet http://www.mouser.com/ds/2/149/FAN5331-92198.pdf FAN5333, datasheet https://www.onsemi.com/pub/Collateral/FAN5333B-D.pdf They ...
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1answer
40 views

Why does an UDN2981 lower the current?

I want to use a UDN2981 8-channel source drivers IC (see UDN 2981 datasheet) for a matrix multiplex light. I connected the UDN2981 this way: pin 9 (VCC) to 5V pin 10 (GND) to GND pin 6 to VCC with a ...
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4answers
83 views

Inverted LED driver circuit

I am looking for an LED driver circuit that would illuminate when a voltage is at zero, and which would gradually shut off as a voltage rises to 3.3v, with a (somewhat) direct relationship between ...
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0answers
30 views

NeoPixel THT: Varying pinouts [closed]

I am in the process of designing a PCB for a solder kit that receives NeoPixel type LEDs, the ones with the short head: Now, there seem to be different pinouts: Ordered on Amazon.de as WS2811 LED ...
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1answer
74 views

How to select the best opamp for a constant current MOSFET driver

I'm trying to create a constant current LED driver. I have found and read information about the miller effect and came up with the schematic below. What are the most important parameters for choosing ...
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1answer
93 views

Why would Discontinuous Conduction Mode be desirable for an LED driver?

I saw this press release where DCM was listed as a feature for a new Infineon driver chip. Source: led-professional.com I'm involved in LED driver design for Horticulture where DCM is undesirable....
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0answers
26 views

Current leak LCD PCB IT-net vs TN-net

I have a LED with LED PCB mounted on a metalic plate that is connected to earth ground. The driver is a cl.2 driver with no earth wire and it's a constand current driver. The lamp is connected to ...
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0answers
19 views

Converting boost controller to sync boost controller using H-bridge or 2 gate drivers

I am trying to reduce power losses in a boost led driver. For example TPS92690, uses a MOSFET and a diode for boost mode. Is it a bad idea to use H-bridge instead, or two gate drivers (one in straight ...
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2answers
167 views

LT3761 LED driver explodes

I am designing a boost LED driver using LT3761 Using the datasheet examples I designed and ordered PCBs, assembled them, but every time I connect the power one of four things explode: fuse, driver, ...
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0answers
60 views

UDN2981 maximum output current too less

For a LED 'matrix kind of' project I want to use UDN2981's for sourcing, and ULN2803's for sinking. I want to use 5mm LEDs, being able to use 100 mA (10% duty cycle). Since the ULN2803 can handle ...
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1answer
109 views

amplifier for 10V LED dimmer control using Raspberry Pi

My problem is I need to have an amplifier circuit design - schematic + components BOM with specific model information that is able to provide a dimmable output signal (Vout) 0.2-10V <0.8A for a set ...
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1answer
52 views

LED ULN2803 thermal / heatsink questions

I'm intending to use LEDs of 5mm, which have a max forward current rate at 30 mA, or a value of 100 mA, with 10% 1 kHz duty cycle, in a circuit like the one below except some changes: STM32F103C8T6 ...
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0answers
81 views

WS2811 LED Strip Driver

I'm in the process of designing a LED strip driver using a WS2811 chip and 3 MOSFETs. I've attached the schematic below. I based it on the reference circuit in the WS2811 datasheet (link), and this ...
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1answer
46 views

PNP array TD62783 output is not closing correctly when input signal goes down

I have TD62783 powered from 12V rail, inputs are driven from 5V rail by HC540. Each output has bunch of leds on the other side along with constant current sink (multiplexed 7 segment display). IC18/...
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1answer
155 views

Constant current source with shunt fet

I'm want to create a project with a LED strobe with IR LEDs. As LEDs the Osram SFH 4249-UV will be used in strings of 15 LEDs and 32 strings parallel. This results in a Vf of 34.5 - 45 V and a If of ...
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2answers
71 views

How can I dampen current spikes when using NPNs to drive an LED

Hi I have the following circuit, its purpose is to flash an LED once per second. I'm using a pair of transistors as a constant current source but I observe current spikes of 20% or so when it is ...
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0answers
48 views

LED Light changes color on being turned on/off simultaneously

What type of circuitry/driver is present in the lights that change color on being turned on/off ? I have a LED tube light which cycles through 3 modes (i.e. color 1, color 2, both color). Its circuit ...
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1answer
57 views

(Backlight) LED Driver maximum number of LEDs

I've been tasked to find a suitable backlight led driver for a Mitsubishi LCD panel (AA104XF12-cf1) which is PWM dimmable, but in my search I've only found confusion. In nearly all datasheets it ...
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0answers
22 views

Which power converter topology has higher benefit of EMI/EMC?

Which power converter topology can be best suited for EMC compliance for small power converter to be used in LED lighting products. In my context I'm using a 5W non-isolated AC-DC converter which is ...
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2answers
91 views

Solar panel as day/night switch for a load

I'm using off-the-shelf components to power a buck/boost LED driver and charge a battery from a 6V solar panel. To power the LED driver from the battery at dusk only, would I have to use a MOSFET ...
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2answers
82 views

Led driver high current and voltage

For a project I have to design a led beacon that will consist of +400 LEDS. These LEDS will be driven only a short amount of time maximum of 3% duty cycle (frequency: 100Hz, pulse: 300us). The LEDS ...
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0answers
26 views

How to turn on & off 50W LED when already using a driver according to limit switches?

I have a 50W UV LED that is going to be installed on a UV printer's head. The printer's head raster, as printers usually do. I would like to turn the LED on only when reaching the printing surface and ...
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1answer
47 views

ATtiny45 program/reset issue

I'm pulling my hair out trying to get this ATtiny45 to work, hopefully someone out there can help. The ultimate goal is to drive an RGB LED strip using PWM, but I'm getting some unreliable behavior ...
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2answers
119 views

SPI control STP16CP05 [closed]

I have this LED driver STP16CP05 https://www.st.com/resource/en/datasheet/stp16cp05.pdf I would want to PWM control 16 mosfets with the 16 outputs of the driver, is that possible or do I need a ...
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1answer
61 views

Can I use a 12V switching power supply to power a G4 LED bulb?

I'm trying to convert a broken halogen lamp to LED using a commonly available G4 bulb. I have a lot of orphaned universal power supplies from various electronic accessories. Can I use a 100-240V => ...
1
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1answer
207 views

Why does this led driver label acl and acn opposite? [closed]

I purchased this led light and it has a driver. But the label for load and neutral are opposite of what I would expect. Note that it says ACL (line) white and ACN (neutral) black. What am I missing ...
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0answers
83 views

Constant Current LED Driver Output Control using PWM

I want to control the brightness of a led which is powered by a constant current driver. On utilizing a MOSFET and pwm signal from an arduino uno the led starts to fade in as the duty cycle ...
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1answer
30 views

led SMPS converter

Which type of converter is best for an LED light for getting better efficiency and high colour rendering index? We want to design a converter up to 80 Watts which gives indirect lighting and less ...
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2answers
103 views

How does a dot matrix led driver know the voltage of an led?

I wanted to make a 7x10 led dot matrix using two 5x7 led dot matrix from lite-on (LTP757KR). I first thought of using shift registers, then I found a 12 x 8 dot matrix led driver with a bunch of ...
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2answers
148 views

Power consumption NeoPixels vs. direct control?

At Maker Faire Berlin 2018, an electrical engineer looked at my project which was shown with NeoPixel LEDs (WS2811). He mentioned that the NeoPixels waste a lot of energy. It would be better to build ...
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1answer
41 views

Need help finding proper Led driver IC

i am an electrical engineering student and have been tasked in creating a quite interesting project. Basically , the whole PCB with the microcontroller and all other parts is already designed, however ...
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1answer
51 views

Driving 8 x 117W COB LEDs [closed]

I am currently attempting to design a LED grow light using the following LEDs but I am having a very hard time finding a sufficient power supply. 8 x Lumileds - SunPlus CoBs DataSheet 51.7 V, ...
2
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2answers
103 views

How does this LED string work?

I have a LED string with four different lights. The lights are in order red, green, yellow and blue and this pattern is repeated. It has a controller with a button to cycle through fading/blinking ...