Help with ic identification on Osram LED tube - Page 1
Forum section: electronics / beginners

author: StijnB91
author_rank: Newbie
timestamp: September 21, 2025, 06:43:55 pm
content: Hello,I am currently looking at repairing the tiny power supply boards of Osram Substitube basic ST8 led tubes. I suspect a led driver ic on the board is broken. Probably this is a non-Isolated Buck APFC LED Driver. It has marking "CS9240S" on it with a product logo and some traceability data. Could someone identify this component? I cannot find it online...Many thanksStijn

author: wraper
author_rank: Unknown
timestamp: September 21, 2025, 07:04:58 pm
content: It's CS9240S from CR Micro (Wuxi China Resources Huajing Microelectronics). Far from everything has documentation available online, or can be bought by individual in small quantities. And some chips like this could be produced for a very short time before being replaced by something else and discontinued.

author: Andy Watson
author_rank: Super Contributor
timestamp: September 21, 2025, 07:16:19 pm
content: This claims to be the datasheet for a CS9240S:https://datasheet.datasheetarchive.com/originals/crawler/hygroup.com.tw/7c276b038688930e9c6d64129457f73e.pdfIt even has the correct number of pins!

author: wraper
author_rank: Unknown
timestamp: September 21, 2025, 07:27:01 pm
content: Quote from: Andy Watson on September 21, 2025, 07:16:19 pmGreat find, I failed finding this one. Likely either compatible ICs were made by multiple companies or same silicon was sold under different Chinese brands which is quite common. Datasheet is from HY Electronic that uses "HY" logo on their parts.

author: wraper
author_rank: Unknown
timestamp: September 21, 2025, 11:49:19 pm
content: Quote from: Andy Watson on September 21, 2025, 07:16:19 pmBTW how did you find it? datasheetarchive does not show it when using their search and it's not googleable either.

author: StijnB91
author_rank: Newbie
timestamp: September 22, 2025, 05:45:12 am
content: Thank you both so much! This info and datasheet is exactly what I need to start testing the chips. Maybe some will still be ok ;-)

author: Andy Watson
author_rank: Super Contributor
timestamp: September 22, 2025, 12:39:22 pm
content: I agree, fiinding datasheets for parts that are of Chinese origin is a bit hit and miss, and even if you do find the correct one, there's a good chance it will be in Chinese!Quote from: wraper on September 21, 2025, 11:49:19 pmTyped CS9240S into duckduckgo. It's now the first result for me.Quote from: wraper on September 21, 2025, 11:49:19 pmThere's your problemIf you get yourself into a google search bubble it's very difficult to escape.

author: wraper
author_rank: Unknown
timestamp: September 22, 2025, 12:59:58 pm
content: ^you won in a lottery. It's totally absent in google, yandex, baidu and brave search. The first result in duckduckgo and bing (which usually produces trash results).

author: jackharry
author_rank: Newbie
timestamp: September 26, 2025, 08:32:30 am
content: Hi Stijn,I’ve done some digging as well, and unfortunately there doesn’t seem to be any publicly available datasheet or listing for an LED driver IC with the marking CS9240S. That usually means one of two things:It’s a house-marked or custom part made specifically for OSRAM or their OEM supplier.Or the code is a shortened/obscured version of a standard LED driver IC, but not indexed under that exact marking.From your description and the typical Substitube ST8 driver topology, it’s very likely a non-isolated buck controller with active PFC, as you suspected. The package and the surrounding passives (sense resistor, inductor, MOSFET, startup resistor) would confirm that.In practice, that makes sourcing the exact IC quite difficult. Most repairers either:Salvage the same IC from another failed board, orReplace the entire driver board with a donor or an aftermarket LED driver module matched to the LED string current/voltage.If you can post a clear close-up photo of the IC and the full PCB (both sides), it might help others here recognize if it matches a better-known driver (there are many from Chipown, Silan, BP, etc. that look similar).So short answer: it’s probably a private-marked LED driver IC, not something easily found retail. Replacing the full driver board may be the more straightforward option.