Need help identifying TI 6855A component

I'm trying to help the OP at the following thread:

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

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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Franc Zabkar

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

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N_Cook

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

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

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- Franc Zabkar

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Franc Zabkar

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

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Reply to
N_Cook

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

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Reply to
N_Cook

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

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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Franc Zabkar

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