F
Franc Zabkar
- Jan 1, 1970
- 0
I'm trying to help the OP at the following thread:
http://forum.hddguru.com/fried-pcb-newest-seagate-drive-where-the-eeprom-chip-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
http://forum.hddguru.com/fried-pcb-newest-seagate-drive-where-the-eeprom-chip-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
