© 2007 Microchip Technology Inc.

DS21930B-page 15

24AAXX/24LCXX/24FCXX

5.7.1

CONTIGUOUS ADDRESSING

ACROSS MULTIPLE DEVICES

Chip Select bits A2, A1 and A0 can be used to expand

the contiguous address space by adding up to eight

24XXs on the same bus. Software can use the three

address bits of the control byte as the three Most

Significant bits of the address byte. For example, in the

24XX32 devices, software can use A0 of the control

byte as address bit A12; A1 as address bit A13; and A2

as address bit A14 (Table 5-1). It is not possible to

sequentially read across device boundaries.

TABLE 5-1:

CONTROL BYTE ADDRESS BITS

Maximum

Devices

Maximum

Contiguous

Address Space

Chip Select Bit

A2

Chip Select Bit

A1

Chip Select Bit

A0

1K (24C01C)

8

8 Kb

A10

A9

A8

1K (24XX014)

8

8 Kb

A10

A9

A8

2K (24C02C)

8

16 Kb

A10

A9

A8

2K (24XX024/025)

8

16 Kb

A10

A9

A8

32K (24XX32)

8

256 Kb

A14

A13

A12

64K (24XX64)

8

512 Kb

A15

A14

A13

128K (24XX128)

8*

1 Mb

A16*

A15*

A14

256K (24XX256)

8*

2 Mb

A17*

A16*

A15

512K (24XX512)

8

4 Mb

A18

A17

A16

* Up to two 24XX128 or 24XX256 devices in the MSOP package can be added for up to 256 kb or 512 kb of address

space, respectively. Bits A0 and A1 must be set to ‘0’.