M24256, M24128

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serial interface that uses a bi-directional data bus

and serial clock. The memory carries a built-in 4-

bit unique Device Type Identifier code (1010) in

protocol, with all memory operations synchronized

by the serial clock. Read and Write operations are

initiated by a START condition, generated by the

bus master. The START condition is followed by a

Device Select Code and RW bit (as described in

Table 3), terminated by an acknowledge bit.

When writing data to the memory, the memory in-

following the bus master’s 8-bit transmission.

When data is read by the bus master, the bus

master acknowledges the receipt of the data byte

in the same way. Data transfers are terminated by

a STOP condition after an Ack for WRITE, and af-

ter a NoAck for READ.

In order to prevent data corruption and inadvertent

write operations during power up, a Power On Re-

set (POR) circuit is included. The internal reset is

POR threshold value, and all operations are dis-

abled – the device will not respond to any com-

operating voltage, below the POR threshold value,

all operations are disabled and the device will not

must be applied before applying any logic signal.

SIGNAL DESCRIPTION

Serial Clock (SCL)

The SCL input pin is used to strobe all data in and

out of the memory. In applications where this line

is used by slaves to synchronize the bus to a slow-

Figure 2A. DIP Connections

Note: 1. NC = Not Connected

SDA

VSS

SCL

WC

NC

NC

VCC

NC

AI01883

M24256

M24128

1

2

3

4

8

7

6

5

Figure 2B. SO Connections

Note: 1. NC = Not Connected

1

AI01884

2

3

4

8

7

6

5

SDA

VSS

SCL

WC

NC

NC

VCC

NC

M24256

M24128

Note: 1. Except for the rating “Operating Temperature Range”, stresses above those listed in the Table “Absolute Maximum Ratings” may

cause permanent damage to the device. These are stress ratings only, and operation of the device at these or any other conditions

above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum Rating condi-

tions for extended periods may affect device reliability. Refer also to the ST SURE Program and other relevant quality documents.

2. IPC/JEDEC J-STD-020A

3. JEDEC Std JESD22-A114A (C1=100 pF, R1=1500

Ω, R2=500 Ω)

Symbol

Parameter

Value

Unit

Ambient Operating Temperature

–40 to 125

°C

Storage Temperature

–65 to 150

°C

Lead Temperature during Soldering

PDIP: 10 seconds

260

235

°C

Input or Output range

–0.6 to 6.5

V

Supply Voltage

–0.3 to 6.5

V

4000

V