What’s the voltage used to power LEDs inside an LED light bulb?

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I have opened an LED light bulb today, and there are two thick wires sticking out of the center to power the LEDs.

I know it will vary by design, but I can’t find even a range of voltages, therefore I ask. What is a typical voltage used to power the LEDs in such an LED lightbulb ?ledShareEditFollowFlagedited 2 hours agoVoltage Spike♦51.4k1212 gold badges5454 silver badges149149 bronze badgesasked 11 hours agoDaniel Wiczew10911 bronze badge New contributor

• 3Depends on country too. And the power supply it has in the base. It all has to do how many LEDs are in series, and if those are single LED packages or multi-LED packages. Guessing 70 to 200 volts. And they are not safe to touch as they can be assumed to be not isolated from mains. – Justme 11 hours ago 
• 2As you said, it varies based on the design. Somewhere from 2V up to 300V. – user253751 10 hours ago
• 2Usually voltage is pretty close to, but lower than, rectified line voltage in order to keep costs low. That is why 9v LED packages exist (3 diodes in series in one package). – user1850479 10 hours ago
• 1Ah, Big Clive is my friend. 🙂 bigclivedotcom on tearing down LED lamps youtube.com/user/bigclivedotcom/search?query=LED+lamp. – tlfong01 6 hours ago   
• 1@tlfong01, bear in mind bigclive is in the UK and they use 240v over there. – Mike Schroedel 3 hours ago
• @Mike Schroedel, I think the Op’s light bulb is 110/120/220/240VAC 50Hz/60Hz compatible. In other words, it is universal/global, one size/bulb fits all thing. But I am only 99% sure. Perhaps I should do some research and post an answer here. Cheers. – tlfong01 1 hour ago   
• 1@Mike Schroedel, I have almost completed my answer. Big Clive’s YouTube (Ref 1) is the best reference I found on power electronics on LED, explaining how the “Capacitive Dropper” is used to interface directly with 110~230VAC, not using transform or switching power circuits. He even guided me how to read the power electronics IC datasheet and commented on the critical part of the schematic. I really enjoyed his lecture! 🙂 – tlfong01 44 mins ago   
• @Daniel Wiczew, Your light bulb was assembled in 2019, so should be using the updated WS3441 (Made in ShenZhen! 🙂 500V PowerMOSFET or similar constant current LED driver (Ref 6 in my answer). Warning: I am just a friendly electronics hobbyist. No guarantee no nothing won’t melt down or blow up. Good Luck. Cheers. – tlfong01 10 secs ago   Edit   

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4 Answers

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White LEDS start at 2.85V and operate near 3V. The designer chooses series, and maybe shunt arrays for redundancy to match the generated voltage. So if there were 80 LEDs that’s almost a 240V string or two 120V strings.

The big contacts in the centre are for mechanical rigidity not current.ShareEditFollowFlaganswered 11 hours agoTony Stewart Sunnyskyguy EE75101k22 gold badges3636 silver badges142142 bronze badgesadd a comment2

Count the LED’s (in series) and multiply by ~2.8V

I did this the other day, get a variable power supply that can go up to 50V and has a current limit.

Plug in the LED’s to the supply with the correct polarity (and make sure the electronics are removed)

Then set a current limit at say 50mA and set the voltage high, like 40 or 50V. Then keep turning up the current limit and watch the voltage go up. When the LED’s get about as bright as they are in the bulb then record the voltage and that’s how much they would take.

Make sure you don’t apply too much voltage, because it could burn them out.ShareEditFollowFlaganswered 10 hours agoVoltage Spike♦51.4k1212 gold badges5454 silver badges149149 bronze badges

• For multi-chip LEDs, it also needs to be multiplied by LED chips in series inside the LED package (which might be 1 but in case it isn’t). – Justme 10 hours ago
• Good point (I guess my count the LED’s statement still holds) – Voltage Spike♦ 10 hours ago

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commonly POWER LEDs are powered with a constant current supplied by a led driver. that means the voltage can vary depending on the temperature of the semiconductor material as well as the it’s type. powering an led with a constant voltage especially a high power one may shorten it’s lifespan significantly.ShareEditFollowFlaganswered 9 hours agoMohamed El Moussaoui1111 bronze badge New contributoradd a comment1

Question

What is a typical voltage used to power the LEDs in such an LED light bulb as show below?

Answer

Short Answer

About 1W LED: from DigiKey:

1. Voltage applied between Anode and Cathode: 3.0 V to 3.5 V (Typical Operating Voltage : 3.3 V)
2. Current through LED (Light Emitting Diode): 300mA to 350mA (350mA being absolute maximum forward current allowed through LED)
3. Operating Life: 100000 hours

/ to continue, …

Long Answer (TL;DR)

References

(1) 6W LED Lamp Teardown With Schematic – Big Clive, 2017jul04

(2) LED Tutorial (Including power LED) – Nick Poole, Bboyho, SparkFun

(3) LED Lamp 1W (3V ~ 3.5V, 300mA ~ 350mA) Tutorial – DigiKey

(4) What’s all this stuff about capacitive power supplies for LEDs? – Lee Teschler 2017jun14

(5) Why do we need all this LED driver stuff, anyway? – Lee Teschler, 2017jun14

(6) WS3441 Non-isolated Buck Offline LED Driver DataSheet -WinSemi

ShareEditDeleteFlagedited 9 mins agoanswered 1 hour agotlfong011,35211 gold badge55 silver badges99 bronze badgesadd a comment