Needing help identifying this 8 pin SMD IC - Page 1
Forum section: electronics / repair

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: June 08, 2022, 02:05:20 pm
content: Hello,This is a small circuit that controls the On/Off, Fan, Peltier unit, tank and power for a small dehumidifier.There is a tactile momentary push button that activates the ON/OFF functions and I believe it to be this chip that handles the relaying.But I'm not sure which SOIC-8 chips do that.Any guidance appreciated.[ Specified attachment is not available ]

author: Ian.M
author_rank: Super Contributor
timestamp: June 08, 2022, 03:00:11 pm
content: Your so-called schematic is useless junk! e.g. an I2C EEPROM cant function with SDA and SCL shorted to Vcc, LEDs D2 and D3 are in series with opposite polarity so cant pass current unless one of them Zeners, which would rapidly damage it, and a 78L05 regulator (U3) cant function with a capacitor in series with its output.Post photo of the actual PCB and a closeup of the chip in question and there's a fair chance someone here will be able to help you. All photos should be well lit, avoiding glare, and in focus, with no camera shake, so that component markings can be clearly read.

author: wraper
author_rank: Unknown
timestamp: June 08, 2022, 06:10:36 pm
content: I did not see the previous version. But it's still a totally useless junk.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: June 08, 2022, 06:16:17 pm
content: Here is a photo of the boardIn case anyone is wondering, the chip in question has nothing on it. Blank.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 08, 2022, 06:16:48 pm
content: Given that there is a I2C EEPROM one would very likely need a µC of some kind somewhere in the circuit. Knowing whih pins are supply may help a little. With a 5 V supply this would likely be a more older type, as newer ones often run from 3.3 V or less. Also likely a type with no internal EEPROM.Chances are high the µC is protected from read out and thus not much help in knowing the type.The circuit plan is still hardly readabel and quite some obvious errors.

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: June 08, 2022, 06:19:51 pm
content: Quote from: Kleinstein on June 08, 2022, 06:16:48 pmThank you for the helpful post.Maybe a photo of the actual board is in orderI posted it above.

author: Ian.M
author_rank: Super Contributor
timestamp: June 08, 2022, 06:22:08 pm
content: Quote from: wraper on June 08, 2022, 06:10:36 pm+1@ThermallyFrigid,While you've fixed up the regulator output and the offending LED, your schematic is still useless junk because the information in it is clearly inaccurate, and as you have removed the pin numbers from U1 that you had in the previous version, you yourself realize that. Usually its preferable to wait to draw up a schematic until you have found datasheets for all active devices, so you can understand the function of each pin you are connecting.Post photos or at a minimum, the exact IC package, all top markings, and a lit of what's connected to which of its pins. If you can't do that, don't bother asking for IC identification help as you are just wasting everybody's time including your own.Thank you for posting a photo. Unfortunately we cant read the IC top markings. Either post an extreme closeup with oblique lighting for better contrast of laser engraved part numbers, or post the text of their top markings. If there are no markings they are probably proprietary, and identifying them non-destructively will be hard.

author: wraper
author_rank: Unknown
timestamp: June 08, 2022, 06:24:13 pm
content: There is no U1 on the PCB. U5 is a MOSFET, but U2 certainly is not 24LC00 (and U2 on schematic is actually U5 on PCB).

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: June 08, 2022, 06:51:06 pm
content: I could not find U5 which has C008N and 113G on it. Nothing at Google, Mouser or Digikey.If anyone knows what this device is that would be helpful.The other device has nothing on it at all.Having an absolutely wonderful time with this hobby regardless of my misfires.I hope everyone else is as well.

author: wraper
author_rank: Unknown
timestamp: June 08, 2022, 06:56:51 pm
content: https://en.sekorm.com/doc/docPdfToHtmlByHtmlCall?docId=2914746&fileCountLimit=10000&showPage=2&cssFont=0

author: mariush
author_rank: Super Contributor
timestamp: June 08, 2022, 06:58:39 pm
content: U5 is definitely a mosfet ... left side all all pins are connected together ... that's probably DRAIN , right side in picture top pin is GATE , and bottom 3 pins are SOURCEMost likely it's FDMC008N08C :https://www.onsemi.com/pdf/datasheet/fdmc008n08c-d.pdfedit : my bad, different footprint ... wraper is probably correct with his link.U3 is linear regulator, U2 is some microcontroller...

author: wraper
author_rank: Unknown
timestamp: June 08, 2022, 06:59:37 pm
content: Quote from: mariush on June 08, 2022, 06:58:39 pmCertainly not, it does not exist in SO8, and marking must be 008N08C

author: mariush
author_rank: Super Contributor
timestamp: June 08, 2022, 07:00:44 pm
content: Yes, thank you, I edited my post already.

author: fzabkar
author_rank: Super Contributor
timestamp: June 08, 2022, 07:27:00 pm
content: 8-pin PICs have Vdd on pin #1 and Vss on pin #8.

author: gamalot
author_rank: Super Contributor
timestamp: June 08, 2022, 07:33:37 pm
content: Quote from: fzabkar on June 08, 2022, 07:27:00 pmMaybe a 8-bit microcontroller from Microchip, like the PIC12F629/675...

author: gamalot
author_rank: Super Contributor
timestamp: June 08, 2022, 07:35:12 pm
content: Quote from: wraper on June 08, 2022, 06:56:51 pmHere is the full version datasheet

author: ThermallyFrigid
author_rank: Frequent Contributor
timestamp: June 08, 2022, 08:52:42 pm
content: On this particular dehumidifier, it's On/Off function is a momentary tactile switch.This is not good for my needs since it is for a closed vehicle prone to considerable heating from the Sun during the day.I don't want the thing running when the vehicle is 120F inside so I like to use a timer to turn it on during the evening when it cools down and then off during the afternoon heating betweem noon and 5 ish.The momentary switch defeats that because anytime the power is cut, it needs a button push to restart.So all of this is in the effort to figure out how to keep all the other functions working but convert it to no switch at all so that it simply powers on when power is available, or it has a rocker type On/Off swiotch.I'm sure others have done this and there may even be a YouTube video on it I'll have to search that.seems this shouldn't be difficult but I was trying to understand the entire circuit before I made any changes.Now you know.......The rest of the story.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 09, 2022, 06:47:31 am
content: With very likely a µC for the control there is not that much that can be done unless the allways on case is planed in the firmware. It would be more like imitating the push bottun on turn on.If the car heats up to some 120 F in most areas the obvious way for dehumitification would be a fan to push air in or out that turns on when the car gets rather hot. Unless in an extremely humid environment and hot on the outside too, this is a rather efficient method to get the car dry.