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.

6

EN25LF20

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

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.

SRP bit / OTP_LOCK bit

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

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

allow the device to be put in the Hardware Protected mode. In this mode, the non-volatile bits of the

Status Register (SRP, BP2, BP1, BP0) become read-only bits.

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.

Write Protection

Applications that use non-volatile memory must take into consideration the possibility of noise and

other adverse system conditions that may compromise data integrity. To address this concern the

EN25LF20 provides the following data protection mechanisms:

Power-On Reset and an internal timer (tPUW) can provide protection against inadvertent

changes while the power supply is outside the operating specification.

Program, Erase and Write Status Register instructions are checked that they consist of a

number of clock pulses that is a multiple of eight, before they are accepted for execution.

All instructions that modify data must be preceded by a Write Enable (WREN) instruction to set

the Write Enable Latch (WEL) bit . This bit is returned to its reset state by the following events:

– Power-up

–

Write Disable (WRDI) instruction completion or Write Status Register (WRSR) instruction

completion or Page Program (PP) instruction completion or Sector Erase (SE) instruction

completion or Block Erase (BE) instruction completion or Chip Erase (CE) instruction

completion

The Block Protect (BP2, BP1, BP0) bits allow part of the memory to be configured as read-only.

This is the Software Protected Mode (SPM).

The Write Protect (WP#) signal allows the Block Protect (BP2, BP1, BP0) bits and Status

Register Protect (SRP) bit to be protected. This is the Hardware Protected Mode (HPM).

In addition to the low power consumption feature, the Deep Power-down mode offers extra

software protection from inadvertent Write, Program and Erase instructions, as all instructions

are ignored except one particular instruction (the Release from Deep Power-down instruction).

TABLE 3. Protected Area Sizes Sector Organization

Status Register

Content

Memory Content

BP2

Bit

BP1

Bit

BP0

Bit

Protect Blocks

Protect

Addresses

Protect

Density(KB)

Protect

Portion

1

1

1

All

000000h-03FFFFh

256KB

All

1

1

0

sector 0 to sector 61

000000h-03DFFFh

248KB

Lower 31/32

1

0

1

sector 0 to sector 59

000000h-03BFFFh

240KB

Lower 30/32

1

0

0

None

None

None

None

0

1

1

All

000000h-03FFFFh

256KB

All

0

1

0

Block 2 to 3

020000h-03FFFFh

128KB

Upper 1/2

0

0

1

Block 3

030000h-03FFFFh

64KB

Upper 1/4

0

0

0

None

None

None

None