ACE34AC04

4K I

VER 1.1

13

Figure 10: Sequential Read

Figure 11: Random Read

Write Protection

The ACE34AC04 incorporates a Reversible Software Write Protection (RSWP) feature that allows the

ability to selectively write protect data stored in each of the four independent 128-byte EEPROM

quadrants. Table 5 identifies the memory quadrant identifier with its associated quadrant, SPA and

memory address locations.

Table 5: Memory Organization

Block

Set Page Address (SPA)

Memory Address Locations

Quadrant 0

0

00h to 7Fh

Quadrant 1

80h to FFh

Quadrant 2

1

00h to 7Fh

Quadrant 3

80h to FFh

(A)

Set RSWP

Setting the RSWP is enabled by sending the Set RSWP command, similar to a normal Write

command to the device which programs the write protection to the target quadrant. The Set RSWP

sequence requires sending a control byte of ‘0110MMM0’ (where ‘M’ represents the memory

quadrant identifier for the target quadrant to be write-protected) with the R/W bit set to a Logic 0. In

conjunction with sending the protocol, the A0 pin must be connected to VHV for the duration of the

RSWP sequence.

The Set RSWP command acts on a single quadrant only as specified in the Set RSWP command

and can only be reversed by issuing the Clear RSWP command and will unprotect all quadrants in

one operation.