What IC is it? - Page 1
Forum section: electronics / beginners

author: Jane
author_rank: Frequent Contributor
timestamp: June 20, 2023, 08:09:02 am
content: I need to repair a charger, for e-bike, made by Stchargers.com.There ,SMD IC marked 71427 seems to be faulty. That IC is marked U1 in the picture.Input voltage seems to be on pin 6 only( there is 12V), other voltages seems to be zero.Anyne knows what IC it is?Thank you.

author: m k
author_rank: Super Contributor
timestamp: June 20, 2023, 09:01:10 am
content: Can't say, picture is too abstract.

author: Jane
author_rank: Frequent Contributor
timestamp: June 20, 2023, 09:48:13 am
content: Here is a picture

author: m k
author_rank: Super Contributor
timestamp: June 20, 2023, 10:20:42 am
content: PWM controller is an obvious first guess but details are avoiding.

author: Jane
author_rank: Frequent Contributor
timestamp: June 21, 2023, 01:46:33 pm
content: I added few more pictures. I removed IC (I marked the place with red).It is an e-bike charger SHC-8100LThe unknown IC ( marked U1 there) is size of 3x2mm

author: Terry Bites
author_rank: Super Contributor
timestamp: June 21, 2023, 02:34:23 pm
content: Hmmm, an LDO seems likely....

author: m k
author_rank: Super Contributor
timestamp: June 21, 2023, 03:46:49 pm
content: So pin 2 out and 3 maybe a feedback,4 and 5 a time constant, with shut off from U2,then 1 and 6 for power.

author: ArdWar
author_rank: Frequent Contributor
timestamp: June 21, 2023, 05:11:52 pm
content: Whatever it is, it's:Driving a 650V NMOS thru Q2, so probably a PWM controllerPin 2 is DRVNot your usual SOT23-6 flyback controller since they usually have DRV on Pin 6Pin 5 is probably FB

author: m k
author_rank: Super Contributor
timestamp: June 23, 2023, 09:31:07 am
content: Quite a bugger, only 6 pins and half clearly known.I'd say that get a new charger and leave this to rainy day modding project, if it's not already.1 GND2 GATE3 SENSE4 FB15 FB26 VccFB seems to have at least CC, CV and zero crossing.SENSE is not very straight forward.Other version has through hole C1, it also have few underside traces.Few guesses.There underside C7 GND connects to C1, here the hole.There Vcc and pin 3 goes to other side of the board, here 0R and C2 holes to R17 and R18 holes.Maybe SENSE is also indicating an AC present.TI should have all kind of oldies available, if the used chip is a copy it's probably from something older.But all I found was one SOT23-6 secondary side PWM, UCC82742.Maybe the chip is not in its primary use.

author: m k
author_rank: Super Contributor
timestamp: July 03, 2023, 04:10:31 pm
content: Seems that "drive by" viewing revealed something.OB2532 has quite exact pinout, some others also.But all are for primary side, and GATE and SENSE are just regular style.One other thought, maybe it's originally for BJT.

author: Jane
author_rank: Frequent Contributor
timestamp: July 04, 2023, 08:44:00 pm
content: Thank you for replies.@m k:Can you please explain more what you mean byall are for primary side, and GATE and SENSE are just regular style.andit's originally for BJT.What is BJT ?

author: m k
author_rank: Super Contributor
timestamp: July 05, 2023, 02:38:40 pm
content: Regular style is how typical application is connected, directly to FET and nothing else.BJT = Bipolar Junction TransistorFET = Field Effect TransistorIn my head transistor is transistor and FET is FET but that is not exactly accurate.