This Data Sheet may be revised by subsequent versions

©2004 Eon Silicon Solution, Inc., www.essi.com.tw

or modifications due to changes in technical specifications.

13

EN25D16

Rev. B, Issue Date: 2008/06/23

Table 6. Status Register Bit Locations

S7

S6

S5

S4

S3

S2

S1

S0

SRP

0

0

BP2

BP1

BP0

WEL

WIP

The status and control bits of the Status Register are as follows:

WIP bit. The Write In Progress (WIP) bit indicates whether the memory is busy with a Write Status

Register, Program or Erase cycle. When set to 1, such a cycle is in progress, when reset to 0 no

such cycle is in progress.

WEL bit. The Write Enable Latch (WEL) bit indicates the status of the internal Write Enable Latch.

When set to 1 the internal Write Enable Latch is set, when set to 0 the internal Write Enable Latch is

reset and no Write Status Register, Program or Erase instruction is accepted.

BP2, BP1, BP0 bits. The Block Protect (BP2, BP1, BP0) bits are non-volatile. They define the size

of the area to be software protected against Program and Erase instructions. These bits are written

with the Write Status Register (WRSR) instruction. When one or both of the Block Protect (BP2, BP1,

BP0) bits is set to 1, the relevant memory area (as defined in Table 3.) becomes protected against

Page Program (PP) Sector Erase (SE) and , Block Erase (BE), instructions. The Block Protect (BP2,

BP1, BP0) bits can be written provided that the Hardware Protected mode has not been set. The

Chip Erase (CE) instruction is executed if, and only if, both Block Protect (BP2, BP1, BP0) bits are 0.

Reserved bit. Status register bit locations 5 and 6 are reserved for future use. Current devices will

read 0 for these bit locations. It is recommended to mask out the reserved bit when testing the

Status Register. Doing this will ensure compatibility with future devices.

SRP bit / OTP_LOCK bit. The Status Register Protect (SRP) bit is operated in conjunction with the

Write Protect (WP#) signal. The Status Register Write Protect (SRP) bit and Write Protect (WP#)

signal allow the device to be put in the Hardware Protected mode (when the Status Register Protect

(SRP) bit is set to 1, and Write Protect (WP#) is driven Low). In this mode, the non-volatile bits of the

Status Register (SRP, BP2, BP1, BP0) become read-only bits and the Write Status Register (WRSR)

instruction is no longer accepted for execution.

In OTP mode, this bit is served as OTP_LOCK bit, user can read/program/erase OTP sector as

normal sector while OTP_LOCK value is equal 0, after OTP_LOCK is programmed with 1 by WRSR

command, the OTP sector is protected from program and erase operation. The OTP_LOCK bit can

only be programmed once.

Note : In OTP mode, the WRSR command will ignore any input data and program OTP_LOCK bit to

1, user must clear the protect bits before enter OTP mode and program the OTP code, then execute

WRSR command to lock the OTP sector before leaving OTP mode.

Status Register Protect

Reserved Bits

Block Protect Bits

Write Enable Latch

Write In Progress