Questions tagged [backlight]

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7 votes
5 answers
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Low Overhead Constant Current LED Driver

I have a 3V3 rail and want to run an LED with a Vf=3.1V at 10mA with a constant current source. I'm used to circuits like the one below but the problem is that I only have 200mV of overhead and ...
EasyOhm's user avatar
  • 4,649
3 votes
2 answers
668 views

Can't understand where backlight pins are in this LCD module

I have this LCD display: RC0802A-BIW-CSX It is supposed to have a backlight, but I can't understand where the backlight LED is since the connections are just 14 pin, and backlight is not mentioned. ...
Felice Pollano's user avatar
3 votes
2 answers
291 views

Voltage doubler for LED backlight

I'm sketching out a design for an easily and cheaply built handheld computer based on an ARM microcontroller, and thinking of using a small LCD display. The display has an LED backlight rated for up ...
Mike Spivey's user avatar
3 votes
1 answer
87 views

LCD module with backlight

I am using COG-C144MVGI. I am trying to turn it on with my Raspberry Pi. I am not sure if I am following the "power on sequence" correctly. Does this kind of LCD modules work without backlight? I am ...
user167987's user avatar
3 votes
2 answers
6k views

What is the purpose of the diodes on a Samsung LED TV backlight bar

Skip to the question below if you don't care about the details ;) The bottom half of the backlight in my TV went off so I opened it up to see if I could fix it. I found four of the 7 bars of LEDs ...
Amrit's user avatar
  • 31
2 votes
3 answers
306 views

Purpose of resistor in inrush current circuit for MIC2289C LED driver

I am looking to use the MIC2289C LED backlight driver from Microchip in a circuit and have a question about the unnamed resistor that connects to the FB pin of the driver and the cathode of the LED ...
jakob's user avatar
  • 462
2 votes
2 answers
453 views

Light sensors sensitive enough to detect for PWM from CF and LEDs?

I have an extreme sensitivity to PWM light sources such as computer screens and light bulbs. This can make it very challenging to make a purchase as I end up having to do lots of guesswork with ...
Zhro's user avatar
  • 2,875
2 votes
1 answer
335 views

Are my calculations for this LED boost driver circuit correct? (TPS61169)

I have a display with the backlight LEDs arranged 6S4P (so 4 parallel strings of 6 LEDs joined internally, so must be driven as single string) and have been trying to find a suitable driver for it - I ...
John U's user avatar
  • 7,110
2 votes
1 answer
211 views

LED backlight hotspot

I have tested a new part number (as replacement) for an LED backlight for an LCD. The LED tested is SML-D15MWT86. We have followed a physical arrangement similar to the original pcb (2 parallel rows, ...
user139731's user avatar
1 vote
1 answer
115 views

In LCD/LED displays, does the back light strobe or remain on?

In LCD/LED displays, like the ones used with computers or for watching TV channels. Does the back light strobe in sync with the refresh rate or does it remain on all the time?
noviceFedora's user avatar
1 vote
1 answer
4k views

Vee negative voltage output LCD

I have a LCD i want to use for a project but still can't get it working on a breadboard. I have used LCD's before so I'm familiar with them, this one however has something i haven't seen before. ...
ardv92's user avatar
  • 97
1 vote
1 answer
64 views

Sensitive instrument 5 V needed

I need advice on powering a STN-display module. I am confused on getting the correct power source for the backlight. The backlight of old module (SP12N002) contained CCFL and new (SP12N01L6ALCZ) is ...
Schultz Hartmut's user avatar
1 vote
1 answer
117 views

Can you damage LCD backlight when you frequently turn it off and on?

I have this small project with PIC microcontroller and LCD display WH1602A-TTI-ET. I am controlling the backlight via software, so I attached it to +5V via PNP ...
Petr's user avatar
  • 487
1 vote
1 answer
723 views

LCD Backlight control brightness adjustment & cathode pin purpose

I'm working on an STM32-based project to which I'm planning to connect an LCD (in my case, it should be 800x480, specifics irrelevant for the questions). I do have disco development boards with LCDs (...
Ilya's user avatar
  • 3,523
1 vote
1 answer
347 views

LCD backlight connection, K pin connected only

I have been trying to build the attached schematic, and my issue lies with LCD backlight. The designer has attached the cathode (K) pin, but not the anode (A) pin. This did not work for me. It is an ...
Ben Rosser's user avatar
1 vote
1 answer
788 views

What is wrong with this LCD backlight boost converter circuit

I have been working with a dev board with the LCD backlight circuit shown below. The boost converted used is the TPS61041. On page 18 of the datasheet, there is an example of the backlight circuit ...
user8908459's user avatar
1 vote
1 answer
142 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 ...
Nathan Prins's user avatar
1 vote
1 answer
3k views

LCD 16x2: circuit to adjust the LCD backlight by a PWM signal

I am testing a lcd 16x2 whith msp430g2553. I am controlling the backlight by PWM signal. I am using the P2.4 as output generating a PWM signal. I have connected the anode directly to pin P2.4 of the ...
FranMartin's user avatar
1 vote
1 answer
1k views

Philips 26PF5321 backlight mod, dim backlight

Got this older Philips 26PF5321 LCD-TV, like it because it is not a smart-tv. What I dislike about this TV is the fixed backlight setting (cannot change it via software menu and there is no update ...
Codebeat's user avatar
  • 1,326
1 vote
0 answers
124 views

Transistor choice for PWM controlled LCD backlight

I have a problem with choosing most appropriate transistor to control backlight of my LCD display. According to datasheet its \$I_f = 60mA\$, and \$V_f = 3.2V\$. My circuitry is all 3.3V based. I ...
Andrzej Komor's user avatar
1 vote
0 answers
37 views

Significance of LED number in selecting inductor and capacitor values in backlight driver circuit

I am looking to configure an LED backlight driver circuit and had a couple questions I was hoping I could find some answers for. My application is a TFT LCD screen with a single anode/cathode input ...
jakob's user avatar
  • 462
1 vote
0 answers
394 views

Replacing a 6 V LED backlight with two 3 V LED backlights

I have a 65" TCL TV which have backlight problem and I have another 60" TCL TV with broken screen. Now when I opened both TV to swap with LED backlighting strips, and I and I noticed the 60&...
Singh's user avatar
  • 11
1 vote
0 answers
78 views

TPS61180 backlight blinks once

I received SmallHD 5" display which was broken by supplying 14.4V by a mistake. It runs on 7.2V typically. The monitor is fine, just the backlight went bad. I replaced TPS61180 right off the bat ...
Maciej Kobus's user avatar
1 vote
0 answers
381 views

Reverse Engineering a Tamura Inverter Board

This is about the pin-out of 9-pin connector 1 of inverter board Tamura HBL-0291, part of a Toshiba Tecra M2 laptop from the early 2000s (see images). The controller chip on the inverter board is ...
farblos's user avatar
  • 11
0 votes
2 answers
938 views

What is the bare minimum number of pins needed to connect to an ILI9488 TFT in order to turn on the LED backlight?

I've bought one of these 3.5" TFT panels: and an accompanying 40-pin FPC-to-header adapter so that I can plug it into a breadboard (specifically, "ILI9488 no touch"). I've got a project ...
Dan Forever's user avatar
0 votes
2 answers
168 views

Which things should I have in mind when choosing LED backlight frequency in range 10 kHz to 100 kHz?

So I have a display which has an integrated LED driver for backlight. The driver expects PWM input with frequency between 10 kHz and 100 kHz. The only other information I have are the maximum voltage ...
AndrejaKo's user avatar
  • 23.4k
0 votes
1 answer
444 views

Do cold cathode fluorescent lights (CCFLs) degrade as a function of idle time?

I have a HP LP2475w display with a cold cathode fluorescent light (CCFL) backlight. It is approximately 8 years old. However, it has only 9041 backlight hours, meaning it has been used for only 12.9% ...
juhist's user avatar
  • 1,631
0 votes
1 answer
789 views

TV backlight LED strip doesn't work, but individual LEDs work fine

There are 9 LEDs (3 V each) connected in series in the LED strip. I tested individual LED with 3 V applied across, and it works fine, but when 9 × 3 V is applied across the whole strip, the LEDs are ...
Allen King's user avatar
0 votes
3 answers
1k views

Transistor with PWM vs LED driver for LCD backlight

I'd like to design a circuit that utilizes a small 1.3" LCD display with maximum LED backlight forward current of 40 mA. Since I'd like to use brightness control, I am hesitating between using a ...
Phill Donn's user avatar
0 votes
2 answers
390 views

2.4" LCD TFT backlight current limit resistor

I have some doubts regarding 2.4 LCD TFT ( NHD-2.4-240320CF-CSXN ) backlight current limit resistor value. Datasheet note is not clear 6. Backlight: White LED / 3.1V / 100 mA ( Typ ) 3.1V means: a) ...
Tomasz Dzikuć's user avatar
0 votes
1 answer
3k views

How to find replacement LED for TV backlight

My TV has a damaged LED in its backlight. The LED had started flickering like 2 weeks ago and finally the whole backlight stopped working. Nothing obviously unusual on the LED driver board, the MOSFET ...
oliver's user avatar
  • 783
0 votes
2 answers
2k views

LCD Backlight Control Circuit

I'm trying to control the back-light of a TC1602A-09T 16X2 Character LCD by using an output pin on a Teensy 3.2 microcontroller. This is the circuit I have at the moment: The LED- pin would be ...
Andrew Schroeder's user avatar
0 votes
2 answers
5k views

Is the voltage supplied by an LCD backlight inverter in a laptop dangerous in any way?

It is my understanding that in a laptop, voltage from a low voltage (say 10V) battery can be converted into higher much higher voltages by way of inverter for an LCD display module. Is this voltage ...
JMan's user avatar
  • 117
0 votes
1 answer
66 views

Troubleshooting digital picture frame backlight not working [closed]

I have one of those old digital picture frame (TELEFUNKEN DPF 9322) and it stopped showing pictures. I took it apart and after some troubleshooting I found out that the issue is the backlight on the ...
JV Lobo's user avatar
  • 355
0 votes
2 answers
59 views

Wireless Keyboard RGB backlight design

I am designing a split wireless keyboard with a 3.7V 2000mAh LiPo battery and using the BQ24075 for power management. I'm contemplating the use 32 of the SK6803 Mini-E for backlighting. Is this ...
ElectronicGlitch's user avatar
0 votes
1 answer
52 views

two PWMs, individual control, 20 LEDs [closed]

Pretty basic requirements: two PWM signals (PWM1, PWM2) 20 individual LEDs sitting behind 20 different symbols (as backlight) normally, when on standby, backlight is 'dim' (PWM1) for all LEDs when a ...
Ariel Narboada's user avatar
0 votes
1 answer
3k views

What is the typical voltage for driving LCD fluorescent backlight tubes?

I ran into this old cockpit/pilot room for heavy mining machinery in which there was an LCD display that's not lit properly, that is, the image was there but the backlight clearly was gone. Upon ...
cream_pi's user avatar
0 votes
2 answers
1k views

How to calclate Rb value for NPN transistor?

Here is a part of my schematic. K pin from LCD is connected to NPN transistor. A pin is connected to Vcc, 5V. Base is connected to uController. It is Atmega16. 5V supply. I am using BC547 transistor ...
cerouno's user avatar
  • 67
0 votes
2 answers
134 views

TI TPS6116 Output Voltage

I am designing an LED backlight driver as a sub-circuit for a DPI interface. The backlight in question requires 12.8V. I am trying to use the TPS61161 and have read through all of the documentation ...
Bassline Soup's user avatar
0 votes
1 answer
927 views

Driving and dimming TFT LCD backlight

I have to add driving/dimming circuit to the design based on NHD-1.8-128160EF-SSXN-F display. The schematics suggested by the manufacturer is practically taken from MIC2289 datasheet (Figure 4-4). ...
Maple's user avatar
  • 12.4k
0 votes
1 answer
53 views

Problem with new bicycle front led light and old bulb back light

I had a problem with my front bulb light at my bicycle. So, I bought a new one (LED) for the front, but somehow, the back bulb does not work anymore. I have checked the wires for loose connection, so ...
Ernte1893's user avatar
  • 183
0 votes
2 answers
1k views

Trick monitor into receiving signal [duplicate]

I have the plan to convert a few old LED backlit monitors into false windows. While I theoretically could buy direct LED drivers to power these panels, I'd prefer to keep the existing circuitry, since ...
Jerry Dodge's user avatar
0 votes
1 answer
259 views

Driving LCDs with parallel LEDs in singles

I am implementing a LED driver for a LCD that has the particular arrangement of the backlight LEDs shown in the picture bellow, 4 parallel LEDs. It seems quite inconvenient not to have them in a ...
Stonie's user avatar
  • 391
0 votes
1 answer
848 views

TFT backlight control via GPIO

I need to control TFT backlight via single GPIO output from atxmega128a4u. The LCD backlight requires +3.0V, while the rest of my schematic runs on +3.3V. I do not have access to backlight ground pin,...
Andrejs Cainikovs's user avatar
0 votes
0 answers
63 views

How can I adjust the brightness of two LCD backlights?

I've just received a PCB I designed with two LCD screens. Unfortunately, the LCDs were black. I think it's due to a wrong schematic for converting BL to LEDK. In the current application code bl is ...
nicco82's user avatar
0 votes
0 answers
49 views

Power switch touch button

I am building a touch industrial panel PC with an embedded motherboard, an LCD panel and a touch sensor. I need a touch button to switch power on/off. I have three questions: How can I switch the ...
Lotfi Bensassi's user avatar
0 votes
0 answers
1k views

GC9A01 LCD display backlight pwm control

I am trying to design a simple smartwatch using ESP32 MCU. For the display I am using GC9A01 LCD screen like this one. I did get display to work by using prototype board, and now I am designing the ...
Marko's user avatar
  • 181
0 votes
0 answers
218 views

Driving LCD backlight using boost converter (Feedback loop & Constant Current)

I've been researching LCD backlight circuits (for my STM32-based project), asked questions before, but there is another question I have about the matter. I have noticed that some boost converters (I ...
Ilya's user avatar
  • 3,523
0 votes
0 answers
154 views

How to test TV LED backlight failure [duplicate]

I recently picked up a Braum (Aldi) TV from the nature strip to play around with. The TV seems to work perfectly fine (Channels, DVD input, sound etc) except that there's no working backlight. I've ...
Mr G's user avatar
  • 113
0 votes
2 answers
428 views

DPI interface for Raspberry Pi including backlight driver

I am designing a DPI interface for my Raspberry Pi ZeroW. I believe the screen I have is exactly the same as the Pimoroni Hyperpixel 4.0 Square, just without the chunky interface PCB. I have the ...
Bassline Soup's user avatar