AS29CF040-55CCIN datasheet(7/27 Pages) ALSC

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Autoselect Mode

The autoselect mode provides manufacturer and device

identification, and sector protection verification, through

identifier codes output on I/O7 - I/O0. This mode is primarily

intended for programming equipment to automatically match

a device to be programmed with its corresponding

programming algorithm. However, the autoselect codes can

also be accessed in-system through the command register.

When using programming equipment, the autoselect mode

requires VID (11.5V to 12.5 V) on address pinA9. Address

pins A6, A1, and AO must be as shown in Autoselect Codes

(High Voltage Method) table. In addition, when verifying

sector protection, the sector address must appear on the

appropriate highest order address bits. Refer to the

corresponding Sector Address Tables. The Command

Definitions table shows the remaining address bits that are

don't care. When all necessary bits have been set as

required, the programming equipment may then read the

corresponding identifier code on I/O7 - I/O0.To access the

autoselect codes in-system, the host system can issue the

autoselect command via the command register, as shown in

the Command Definitions table. This method does not

require VID. See "Command Definitions" for details on using

the autoselect mode.

Table 3. AS29CF040-55CCIN Autoselect Codes (High Voltage Method)

Description

A18 - A16 A15 - A10 A9 A8 - A7 A6 A5 - A2 A1

Identifier Code on

I/O7 - I/O0

Manufacturer ID:

Alliance Memory

VID

VIL

37h

Device ID:

AS29CF040-55CCIN

VID

VIL

VIH

86h

01h (protected)

Sector Protection

Verification

Sector

Address

VID

VIL

VIH

VIL

00h (unprotected)

Continuation ID

VID

VIL

VIH

7Fh

Sector Protection/Unprotection

The hardware sector protection feature disables both

program and erase operations in any sector. The hardware

sector unprotection feature re-enables both program and

erase operations in previously protected sectors.

Sector protection/unprotection must be implemented using

programming equipment. The procedure requires a high

voltage (VID) on address pin A9 and the control pins.

The device is shipped with all sectors unprotected.

It is possible to determine whether a sector is protected or

unprotected. See "Autoselect Mode" for details.

Hardware Data Protection

The requirement of command unlocking sequence for

programming or erasing provides data protection against

inadvertent writes (refer to the Command Definitions table).

In addition, the following hardware data protection measures

prevent accidental erasure or programming, which might

otherwise be caused by spurious system level signals during

VCC power-up transitions, or from system noise. The device

is powered up to read array data to avoid accidentally writing

data to the array.

Write Pulse "Glitch" Protection

Noise pulses of less than 5ns (typical) on

OE ,CE or WE

do not initiate a write cycle.

Logical Inhibit

Write cycles are inhibited by holding any one of

OE =VIL,

CE = VIH or WE = VIH. To initiate a write cycle, CE and

WE must be a logical zero while OE is a logical one.

Power-Up Write Inhibit

WE = CE = VIL and OE = VIH during power up, the

device does not accept commands on the rising edge of

WE . The internal state machine is automatically reset to

reading array data on the initial power-up.

Command Definitions

Writing specific address and data commands or sequences

into the command register initiates device operations. The

Command Definitions table defines the valid register

command sequences. Writing incorrect address and data

values or writing them in the improper sequence resets the

device to reading array data.

All addresses are latched on the falling edge of

WE or CE ,

whichever happens later. All data is latched on the rising

edge of

WE or CE , whichever happens first. Refer to the

appropriate timing diagrams in the "AC Characteristics"

section.

Reading Array Data

The device is automatically set to reading array data

after device power-up. No commands are required to

retrieve data. The device is also ready to read array

data after completing an Embedded Program or

Embedded Erase algorithm. After the device accepts

an Erase Suspend command, the device enters the

Erase Suspend mode. The system can read array

data using the standard read timings, except that if it

reads at an address within erase-suspended sectors,

the device outputs status data. After completing a

programming operation in the Erase Suspend mode, the

AS29CF040-55CCIN

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Rev.1.0. July 2019

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