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Problem with 24256 eeproms as they don't respond to I2C device codes

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ben123

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i bought 24256 eeproms.

they are only responding i2c device code A0, other codes A2,A4,A6,A8 .. etc not work. i have pcb with six 24lc256 (device code from A0 to AA. )

i put one 24256 to A0 socket eveything is ok.
then i move same part to A2 it still responds as A0. A4,A6,A8,AA still same. it still responds to A0.

24lc256 eeproms have tree pins to select device address. all of them connected to +5V, every of them responds to A0 device code.

today i buy four part to test from another shop. nothing changed.

i removed an older 24256 produced by Microchip from one of my circuits, and test with that one everything ok.

these problematic parts are marked as:
PHIL N
24256 8
LP6135 //not 8135

and bottom side
24256NC
M112854

i looked to philips web site, no information. i searched for datasheet, no chance.

do you know anything about this?
 

XNOX_Rambo

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eeprom 24256

There are types of EEPROMs that have one or two address pins connected to GND
internally. Both Microchip and ST have these types, but I don't know about Philips.

/Rambo
 

ben123

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Re: 24256 eeprom problem

mmm, you must right.

because, it has a logo ST and right side of the logo there is a text PHIL
strange. i think it is a philips but seems not. after your post, i looked with magnifying glass then i saw this detail. i gave wrong information, my error, i'm sorry.

i understand. i never heard it before!

thanks very much XNOX_Rambo.

why are they connect address pins to gnd !?!, my homework. i'm going search datasheets for this type of eeproms.

i must find another projects to use these parts.
 

XNOX_Rambo

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Re: 24256 eeprom problem

I think PHIL stands for "Philipines", where chips have been packaged for many
years now.

I have no idea why they don't connect all address pins, as the packages I have
seen have enough pins. Anyway, when using second source chips one must
remember to check every detail in the datasheets - sad, but true...

Good luck!

/Rambo
 

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