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M34D64-WDW6

64 Kbit Serial I²C Bus EEPROM With Hardware Write Control on Top Quarter of Memory

STMicroelectronics 

M34D64

SUMMARY DESCRIPTION

These I2C-compatible electrically erasable

programmable memory (EEPROM) devices are

organized as 8192 x 8.

Figure 2. Logic Diagram

VCC

3

E0-E2

SCL

WC

M34D64

SDA

VSS

AI02850B

Table 1. Signal Names

E0, E1, E2

Chip Enable

SDA

Serial Data

SCL

Serial Clock

WC

Write Control

VCC

VSS

Supply Voltage

Ground

Power On Reset: VCC Lock-Out Write Protect

In order to prevent data corruption and inadvertent

Write operations during Power-up, a Power On

Reset (POR) circuit is included. The internal reset

is held active until VCC has reached the POR

threshold value, and all operations are disabled –

the device will not respond to any command. In the

same way, when VCC drops from the operating

voltage, below the POR threshold value, all

operations are disabled and the device will not

respond to any command. A stable and valid VCC

must be applied before applying any logic signal.

These devices are compatible with the I2C

memory protocol. This is a two wire serial interface

that uses a bi-directional data bus and serial clock.

The devices carry a built-in 4-bit Device Type

Identifier code (1010) in accordance with the I2C

bus definition.

The device behaves as a slave in the I2C 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 2),

terminated by an acknowledge bit.

When writing data to the memory, the device

inserts an acknowledge bit during the 9th bit time,

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 after a

NoAck for Read.

Figure 3. SO and TSSOP Connections

M34D64

E0 1

E1 2

8 VCC

7 WC

E2 3

6 SCL

VSS 4

5 SDA

AI02851C

Note: 1. See page 17 (onwards) for package dimensions, and how

to identify pin-1.

2/21

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