2

Signal description

2.1

Serial clock (SCL)

The signal applied on the SCL input is used to strobe the data available on SDA(in) and to output the data on

SDA(out).

2.2

Serial data (SDA)

SDA is an input/output used to transfer data in or data out of the device. SDA(out) is an open drain output that

may be wire-OR’ed with other open drain or open collector signals on the bus. A pull-up resistor must be

connected from serial data (SDA) to VCC (Figure 12 indicates how to calculate the value of the pull-up resistor).

2.3

Chip enable (E2, E1, E0)

(E2,E1,E0) input signals are used to set the value that is to be looked for on the three least significant bits (b3, b2,

b1) of the 7-bit device select code (see Table 3). These inputs must be tied to VCC or VSS, as shown in Figure 4.

When not connected (left floating), these inputs are read as low (0).

Figure 4. Chip enable inputs connection

VCC

M24xxx

VSS

Ei

VCC

M24xxx

VSS

Ei

2.4

Write control (WC)

This input signal is useful for protecting the entire contents of the memory from inadvertent write operations. Write

operations are disabled to the entire memory array when write control (WC) is driven high. Write operations are

enabled when write control (WC) is either driven low or left floating.

When write control (WC) is driven high, device select and address bytes are acknowledged, data bytes are not

acknowledged.

2.5

VSS (ground)

VSS is the reference for the VCC supply voltage.

M24512-W M24512-R M24512-DF

Signal description

DS6520 - Rev 31

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