Part identification - Page 1
Forum section: electronics / repair

author: maxmad
author_rank: Contributor
timestamp: January 12, 2019, 12:50:13 am
content: Can anyone help to identify this IC?I think it's a TSSOP-8 package.

author: amyk
author_rank: Super Contributor
timestamp: January 12, 2019, 03:27:30 am
content: Can you provide more context? The package suggests serial EEPROM but I couldn't immediately find a match.

author: maxmad
author_rank: Contributor
timestamp: January 12, 2019, 08:14:28 pm
content: This is the real PCB.It is from the base charger:https://www.amazon.ca/COXO-Curing-DB-685-Whitening-Supply/dp/B00EJELGM4After some time 3-4 minutes , the power led turns from green to orange. And there is no voltage at the base to charge the "stick".Put my finger above this component, without touching it, the led turns green again! and voltages are ok.

author: fzabkar
author_rank: Super Contributor
timestamp: January 12, 2019, 09:04:33 pm
content: Q1 appears to provide the charging current for the stick.https://www.diodes.com/assets/Datasheets/FZT788B.pdfThe base of Q1 is driven by the IC, so I'm guessing it's a battery charger IC. The following URL suggests that it is a Texas Instruments part, but the supplier appears to know little more than that:https://www.kynix.com/Detail/386192/B257C.htmlI tried BQ257... but no luck.

author: maxmad
author_rank: Contributor
timestamp: January 12, 2019, 11:41:42 pm
content: does it make sense if it is a6257 ?https://www.analog.com/media/en/technical-documentation/data-sheets/625567fd.pdfalso comes at MS8 package.this based on this supplier:https://www.aliexpress.com/item/New-6257C-TSSOP8-MSOP8-SMD-ultra-eight-feet-imported-genuine-chips/1321847071.html?spm=a2g17.10010108.1000001.8.5b3713710ZOf79identifying the chip as 6257

author: Armadillo
author_rank: Super Contributor
timestamp: January 12, 2019, 11:48:24 pm
content: I think more likely to do with linear LED driver or controller, obviously with external transistor buffer.Can you take the photo of the PCB from the other side, since some components are there.Quote from: maxmad on January 12, 2019, 11:41:42 pm

author: fzabkar
author_rank: Super Contributor
timestamp: January 13, 2019, 12:10:43 am
content: I would think that the two central solder pads would connect to the battery terminals in the stick. R12 appears to be an 0.2 ohm current sense resistor.

author: maxmad
author_rank: Contributor
timestamp: January 23, 2019, 09:10:13 pm
content: There are no components on the other side of the pcb. Only traces.I drew some of them.The Vcc pin of the part takes voltage from Input Voltage just after D2. These are pins 3-8.Pin 1 also has similar voltage to Vcc due to R12. Too many pins IMO. Maybe there is an inside shortcut. Device fault comes after a wrong power adapter was used.The Gnd pin is 6Q1 collector is connected to pin 2.Seems that LTC6257 doesn't meet the requirements...

author: fzabkar
author_rank: Super Contributor
timestamp: January 23, 2019, 10:13:53 pm
content: Although the marking differs, the pinout appears to match the BQ2057C (SOIC or TSSOP packages):http://www.ti.com/lit/ds/symlink/bq2057c.pdf

author: maxmad
author_rank: Contributor
timestamp: February 12, 2019, 06:35:02 pm
content: Great info! BQ2057C ordered and replaced !Device works fine!

author: ann
author_rank: Newbie
timestamp: September 19, 2019, 07:22:07 am
content: How do I figure out how many transistors are required to build a given type of gate? anyone can help me? thank you so much.

author: Simon
author_rank: Unknown
timestamp: September 19, 2019, 11:37:42 am
content: Quote from: ann on September 19, 2019, 07:22:07 amyou start by not digging up a topic that is months old that no one will reply on and generates suspicion as to your real intentions.