Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems.

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Default Need help identifying TI 6855A component

I'm trying to help the OP at the following thread:
http://forum.hddguru.com/fried-pcb-n...ip-t24422.html

I'm fairly certain that the problem is a shorted TVS diode, but I'm
curious as to the identify of a 16-pin chip with the following
markings:

6855A
TI 271
A1CJ

It is located just below the 4-pin jumper block, and at about 10
o'clock to the MCU (the largest IC).

I suspect that it was made by Texas Instruments, and that it may be a
step-down PWM regulator with integrated MOSFET and diode.

A datasheet search at TI's web site found no items containing "6855".

The board appears to have 5 switchmode supplies (there are 5
inductors), with one being a -5V supply and the others probably being
positive step-down regulators. One would provide +1.8V for the SDRAM
and flash memory, while the others would provide the Vcore and Vio
supplies for the MCU.

- Franc Zabkar
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Default Need help identifying TI 6855A component

On Fri, 09 Nov 2012 19:33:13 +1100, Franc Zabkar
put finger to keyboard and composed:

6855A
TI 271
A1CJ


The "271" looks like a data code, maybe week 1 of the 7th month
(July), 2012.

The date codes on other ICs include 228, 229, 1228, 231 which would be
consistent.

Could it be a Japanese part?

- Franc Zabkar
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Default Need help identifying TI 6855A component

Franc Zabkar wrote in message
...
On Fri, 09 Nov 2012 19:33:13 +1100, Franc Zabkar
put finger to keyboard and composed:

6855A
TI 271
A1CJ


The "271" looks like a data code, maybe week 1 of the 7th month
(July), 2012.

The date codes on other ICs include 228, 229, 1228, 231 which would be
consistent.

Could it be a Japanese part?

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.


Is it FQN-16 footprint? if so probably .cn origin


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Default Need help identifying TI 6855A component

On Mon, 12 Nov 2012 12:16:12 -0000, "N_Cook" put
finger to keyboard and composed:

Is it FQN-16 footprint? if so probably .cn origin


I don't have access to the actual board. All I have are the photos in
that thread ...

http://www.users.on.net/~fzabkar/HDD/6855A.jpg

- Franc Zabkar
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Default Need help identifying TI 6855A component

Franc Zabkar wrote in message
...
On Mon, 12 Nov 2012 12:16:12 -0000, "N_Cook" put
finger to keyboard and composed:

Is it FQN-16 footprint? if so probably .cn origin


I don't have access to the actual board. All I have are the photos in
that thread ...

http://www.users.on.net/~fzabkar/HDD/6855A.jpg

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.



presumably these grey market "Texas Instr", complete with erroneous col
headers. Difficult to be sure they are QFN-16 in your pic

http://www.szspl-ic.com/en/IcStock.aspx?page=84&pp=TI






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Default Need help identifying TI 6855A component

Franc Zabkar wrote in message
...
On Mon, 12 Nov 2012 12:16:12 -0000, "N_Cook" put
finger to keyboard and composed:

Is it FQN-16 footprint? if so probably .cn origin


I don't have access to the actual board. All I have are the photos in
that thread ...

http://www.users.on.net/~fzabkar/HDD/6855A.jpg

- Franc Zabkar
--
Please remove one 'i' from my address when replying by email.



presumably these grey market "Texas Instr", complete with erroneous col
headers. Difficult to be sure they are QFN-16 in your pic

http://www.szspl-ic.com/en/IcStock.aspx?page=84&pp=TI




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Default Need help identifying TI 6855A component

On Tue, 13 Nov 2012 08:54:04 -0000, "N_Cook" put
finger to keyboard and composed:

presumably these grey market "Texas Instr", complete with erroneous col
headers.


It's from a Seagate hard drive. I doubt that Seagate would source
their components from dubious outlets.

Could it be "T1" (tee one) rather than TI (tee eye)?

- Franc Zabkar
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Please remove one 'i' from my address when replying by email.
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