Component help TP4122 6 pin SMD IC - Page 1
Forum section: electronics / repair

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 01:28:33 pm
content: Hi!A good friend of mine brought to my workbench quite a powerful LED bar with couple of blown mosfets, but also an IC with the marking TP4122. This IC is impossible to find on the webb and thought maybe one of you guys seen it before or recognise it from a similar circuit. I made a schematic so you can see what I am talking about and this LED driver is supposed to work with a Vin from 9 to 36 volts.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 26, 2024, 01:30:30 pm
content: https://electronics.stackexchange.com/questions/689605/can-someone-help-me-to-identify-this-6-pin-smd-icis you?I'll try to find it.

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 01:35:28 pm
content: Thank you squadchannel!Yes, I saw that one too and there are only two hits on this IC when I Google it.

author: squadchannel
author_rank: Frequent Contributor
timestamp: August 26, 2024, 01:45:59 pm
content: hmmm... Can't find it.

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 01:51:51 pm
content: Yes, this was a hard one to find! I will have to look more closely on this circuit and try to get how it works, but I have to confess that just a quick look at it make me nervous!

author: fzabkar
author_rank: Super Contributor
timestamp: August 26, 2024, 03:04:00 pm
content: Here is an IC with similar pinout and function (PT4121):http://micro-bridge.com/data/crpowtech/PT4121C.pdfIt's available from LCSC (PT4121 and PT4121E):https://www.lcsc.com/search?q=PT4121

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 03:33:05 pm
content: WOW!! Thank you so much fzabkar!I did not do my search well!I have spent quiet some time to find anything on this IC but but failed and you found it within a very ... very short time and even where to order them. Thank you once again! When I get this LED driver working, which actually consists of four equal drivers (two pcb's) and in total controlling 40 leds, I will get back.

author: fzabkar
author_rank: Super Contributor
timestamp: August 26, 2024, 03:51:58 pm
content: I think you need to be mindful of the current sense resistor and how it determines the LED current. For the PT4121 IC, the result appears to be ...Iout=0.2/Rcs = 0.2 / 0.089 = 2.25 ampsThe TP4122 may not be the same.

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 04:04:14 pm
content: Yes you are right about the current sense resistors and they may have to be recalculated. One thing more that I do not understand is that there is no power to the VCC pin on this TP4122. I have to check the pcb again if I missed something!

author: 4cx10000
author_rank: Regular Contributor
timestamp: August 26, 2024, 04:13:16 pm
content: Oh ... I was a bit careless when I watched the datasheet, pin 6 is Vo Adj.Edit ... it is, as I understand now, VCC; I did it once again!

author: fzabkar
author_rank: Super Contributor
timestamp: August 26, 2024, 04:22:17 pm
content: This appears to be the manufacturer of the TP4122, but no datasheet. They also make a TP4121 in an SOT23-6 package.http://tpower-ic.com/en/product-61925-53548-145300.html