AN3355

Summary

Doc ID 018544 Rev 2

9/11

3

Summary

When designing an application board that will accept either M24LRxx-R or M24LRxxE-R,

the following rules should be kept in mind:

M24LRxx-R

The Device Select byte (first byte transmitted by the I²C-bus master selecting the device to

be accessed) is defined as shown in Table 3.

The inputs E0,E1 have to be defined as 0,0 (which is the case when the E0,E1 pins are left

unconnected). The Device Select byte is therefore:

●

either 1.0.1.0. 0.0.0.RW (where RW is the Read/Write bit) when addressing data in the

memory array,

●

or 1.0.1.0. 1.0.0.RW (where RW is the Read/Write bit) when addressing the system

parameter sector.

M24LRxxE-R

In this case of PCB implementation, the E0 and E1 inputs are connected to the power

supply management block and the WIP/Busy output is connected to a high impedance

input, as shown in Figure 2.

The Device Select byte (first byte transmitted by the I²C-bus master) defines the device to be

selected. The Device Select byte is defined as shown in the following table.

The Device Select byte is therefore:

●

either 1.0.1.0. 0.1.1.RW (where RW is the Read/Write bit) when addressing data in the

memory array,

●

or 1.0.1.0. 1.1.1.RW (where RW is the Read/Write bit) when addressing the system

parameter sector.

Table 3.

M24LRxx-R Device Select byte

1.

The most significant bit, b7, is sent first.

2.

E0 and E1 are compared against the respective external pins on the memory device.

RW

b7

b6

b5

b4

b3

b2

b1

b0

Device select code

1010

3.

E2 selects either the memory of the system sector.

E1

E0

RW

Table 4.

M24LRxxE-R Device Select byte

1.

The most significant bit, b7, is sent first.

Chip Enable address

RW

b7

b6

b5

b4

b3

b2

b1

b0

Device select code

1010

2.

E2 selects either the memory of the system sector.

11

RW