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[moved] Unidentified EEPROM (markings: TO2 HG)

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Aug 12, 2015
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What I know:
- it is EEPROM memory
- dimension (main body): 3 x 3 x 0.5 millimeters
- markings: TO2 HG

What I guess:
- memory size: 256 Bytes
- Vin: 3.3V

What I want to know:
- interface/pinout (I2C, Microwire or something?)

Its predecessor had Microwire EEPROM (Vin, GND, SC, CS, DI, DO) connected to SDIO bus (10k resistor between DO and DI-SDIO).

At first glance, it is family 24xxxx.
Is it possible that this was something else, such redesigned Microwire EEPROM with a single SDIO bus instead of DI and DO?

That is an unusual package for a standard EEPROM and almost all 24xxxx and 25xxxx have a full part number on them. With all the pins along one side connected together it could be a MOS power switch of some kind. What is the product? Can you show a picture of it with more surrounding parts so we can see it in context of it's likely function.


This is a print head, the back side of the contact plate.

IC is not connected to the nozzles (except for Vin and GND).
Each of the unrecognized leg IC has a contact on the contact plate.

Since the introduction of memory to the print head, it's always been microwire.
Preceded had memory TC9WMC2
(256 Bytes, 16-bit, 3.3V, 4 functional pins: serial clock, select, data in, data out).
TC9WMC2 is easy to read and write.

I suspect the new 3-wire memory is microwire with internally joined "serial in" and "serial out" through 10k resistor.
Here is a evolution of EEPROM memory connection to CPU:


If it's on a print head it could be anything. If it's on an ink cartridge it will be the cycle counter and also hold some manufacturers ID numbers. The '02' would refer to a 2K bit device and from your circuit description it would be 2nd generation according to your diagram. All these devices contain an internal manufacturer code and ID, if you can connect it to a programmer it should be able to read and identify what type of memory it is and who made it.


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