Could you help me ID a component on a LiPo protection board? - Page 1
Forum section: electronics / beginners

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 11, 2022, 06:11:05 pm
content: This is for a 1S LiPo I am using for a project in the shed.First let me apologize for my schematic, I've never really drawn one and I know looking at it will trigger a good many of you. The component is a SOT-26 and the marking was y1ig (Removed from PCB in pic and is marked U1 on the solder mask). I didn't draw in all of those 6 other chips (Also not able to find data on those based on markings) as they are all wired in parallel so I only drew in one. U1 is the component in question and I think it's a MOSFET and i feel it may be this one . Of course the # on the PCB comes back to nothing either. I "assume" that pin one is on the side o U1 w/ the line and if so pin 5 (Drain2) of this chip is not in use.Thanks much guysDave

author: tepalia02
author_rank: Regular Contributor
timestamp: June 13, 2022, 10:58:31 am
content: Looks close to this one:https://www.evelta.com/dw01a-sot23-6-one-cell-lithium-ion-polymer-battery-protection-ic/

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 15, 2022, 04:16:08 am
content: Very similar. The low voltage cutoff is acceptable for 18650s but I'd rather not have my lipos that discharged. Looking for a 2.9xv min voltage. But this is a good start

author: sleemanj
author_rank: Super Contributor
timestamp: June 15, 2022, 06:19:16 am
content: The chips in parallel are the MOSFETs (probably "8205A" or similar dual mosfets)U1 will be the protection IC.Q6 would b a 6th MOSFET the same as the othersSOT-23-6 is a common size for such ICs, the DW01 is the jellybean part in this category, but others exist, but they don't all have the same pinout even if they are almost always about this size.Here's one which has a closer lower voltage cut off, I have not compared pinout to your drawing.TC2120-CBhttps://datasheet.lcsc.com/lcsc/2204191145_Shenzhen-Fuman-Elec-2120-CB_C126202.pdfhas a 2.9V lower cut off and 3v release, but has quite a high overcharge cut off of aroudn 4.3v depending on binningI found this by using the JLC parts databasehttps://yaqwsx.github.io/jlcparts/#/select Power Management ICs>Battery Management ICs, select SOT-23-6 and SOT-23-6L and sort by most stock, this was 3rd from the top.(about about 200 more, of course some of these are chargers, some are protection, many have chinese datasheets, but you soon get to see what the patterns are and can glance at the datasheet numbers and diagram to see what's going on)

author: Peabody
author_rank: Super Contributor
timestamp: June 15, 2022, 02:34:53 pm
content: Can someone explain what the circuit actually does? If there's only one DW01, but six dual mosfets, then is the DW01 only reading one of the six cells, but switching all of them based on that?

author: gamalot
author_rank: Super Contributor
timestamp: June 15, 2022, 03:15:30 pm
content: Quote from: Peabody on June 15, 2022, 02:34:53 pmIt doesn't work like you think, the only purpose of those 6 MOSFETs in parallel is to provide high current capability, doesn't matter if the battery is single or multiple in parallel.

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 16, 2022, 12:16:55 am
content: Thanks guys. I will look into this. I did some more looking into this circuit, can someone tell me why the drains seem to go nowhere? I checked pinout 10 times over and still could not find anyplace those MOSFET drains go on either of those boards I have now (The amazon and the one that was on my battery)Dave

author: thm_w
author_rank: Super Contributor
timestamp: June 16, 2022, 12:54:28 am
content: Quote from: TT_Vert on June 16, 2022, 12:16:55 amDrain FET1A connects to Drain FET1Bhttps://www.eevblog.com/forum/projects/pain-and-suffering-getting-the-dw01-and-8205a-protection-circuit-work-right/So current cannot flow in either direction.

author: TT_Vert
author_rank: Regular Contributor
timestamp: June 23, 2022, 03:16:33 am
content: Thank you all for the info.