Author Topic: Part identification  (Read 1109 times)

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Offline maxmad

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Part identification
« on: January 12, 2019, 12:50:13 am »
Can anyone help to identify this IC?

I think it's a TSSOP-8 package.


 

Offline amyk

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Re: Part identification
« Reply #1 on: January 12, 2019, 03:27:30 am »
Can you provide more context? The package suggests serial EEPROM but I couldn't immediately find a match.
 

Offline maxmad

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Re: Part identification
« Reply #2 on: January 12, 2019, 08:14:28 pm »
This is the real PCB.

It is from the base charger:
https://www.amazon.ca/COXO-Curing-DB-685-Whitening-Supply/dp/B00EJELGM4

After 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.
 

Offline fzabkar

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Re: Part identification
« Reply #3 on: January 12, 2019, 09:04:33 pm »
Q1 appears to provide the charging current for the stick.

https://www.diodes.com/assets/Datasheets/FZT788B.pdf

The 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.html

I tried BQ257... but no luck.
 
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Offline maxmad

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« Last Edit: January 12, 2019, 11:44:30 pm by maxmad »
 

Offline Armadillo

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Re: Part identification
« Reply #5 on: January 12, 2019, 11:48:24 pm »
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.

does it make sense if it is a

6257  ?


https://www.analog.com/media/en/technical-documentation/data-sheets/625567fd.pdf

also 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=a2g17.10010108.1000001.8.5b3713710ZOf79

identifying the chip as 6257
 

Offline fzabkar

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Re: Part identification
« Reply #6 on: January 13, 2019, 12:10:43 am »
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.
 

Offline maxmad

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Re: Part identification
« Reply #7 on: January 23, 2019, 09:10:13 pm »
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 6

Q1 collector is connected to pin 2.

Seems that LTC6257 doesn't meet the requirements...    :(
 

Offline fzabkar

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Re: Part identification
« Reply #8 on: January 23, 2019, 10:13:53 pm »
Although the marking differs, the pinout appears to match the BQ2057C (SOIC or TSSOP packages):
http://www.ti.com/lit/ds/symlink/bq2057c.pdf

 
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Offline maxmad

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Re: Part identification
« Reply #9 on: February 12, 2019, 06:35:02 pm »
Great info! BQ2057C ordered and replaced !
Device works fine!
 

Offline ann

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question about transistor
« Reply #10 on: September 19, 2019, 07:22:07 am »
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.
 

Online Simon

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Re: Part identification
« Reply #11 on: September 19, 2019, 11:37:42 am »
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.

you 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.
 


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