W29C040 Ver la hoja de datos (PDF) - Winbond

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W29C040

512K ·8 CMOS FLASH MEMORY

Winbond 

W29C040

required. For information about specific codes, see the Command Codes for Software Data Protection

in the Table of Operating Modes. For information about timing waveforms, see the timing diagrams

below.

Hardware Data Protection

The integrity of the data stored in the W29C040 is also hardware protected in the following ways:

(1) Noise/Glitch Protection: A #WE pulse of less than 15 nS in duration will not initiate a write cycle.

(2) VDD Power Up/Down Detection: The write and read operation are inhibited when VDD is less than

2.5V.

(3) Write Inhibit Mode: Forcing #OE low, #CE high, or #WE high will inhibit the write operation. This

prevents inadvertent writes during power-up or power-down periods.

(4) VDD power-on delay: When VDD has reach its sense level, the device will automatically time-out 10

mS before any write (erase/program) operation.

Chip Erase Modes

The entire device can be erased by using a six-byte software command code. See the Software Chip

Erase Timing Diagram.

Boot Block Operation

There are two boot blocks (16K bytes each) in this device, which can be used to store boot code. One

of them is located in the first 16K bytes and the other is located in the last 16K bytes of the memory.

The first 16K or last 16K of the memory can be set as a boot block by using a seven-byte command

sequence.

See Command Codes for Boot Block Lockout Enable for the specific code. Once this feature is set the

data for the designated block cannot be erased or programmed (programming lockout); a regular

programming method can change other memory locations. Once the boot block programming lockout

feature is activated, the chip erase function will be disabled. In order to detect whether the boot block

feature is set on the two 16K blocks, users can perform a six-byte command sequence: enter the

product identification mode (see Command Codes for Identification/Boot Block Lockout Detection for

specific code), and then read from address "00002 hex" (for the first 16K bytes) or "7FFF2 hex" (for the

last 16K bytes). If the output data is "FF hex," the boot block programming lockout feature is activated;

if the output data is "FE hex," the lockout feature is inactivated and the block can be programmed.

To return to normal operation, perform a three-byte command sequence to exit the identification mode.

For the specific code, see Command Codes for Identification/Boot Block Lockout Detection.

Data Polling (DQ7)- Write Status Detection

The W29C040 includes a data polling feature to indicate the end of a write cycle. When the W29C040

is in the internal write cycle, any attempt to read DQ7 of the last byte loaded during the page/byte-load

cycle will receive the complement of the true data. Once the write cycle is completed. DQ7 will show

the true data. See the #DATA Polling Timing Diagram.

Toggle Bit (DQ6)- Write Status Detection

In addition to data polling, the W29C040 provides another method for determining the end of a write

cycle. During the internal write cycle, any consecutive attempts to read DQ6 will produce alternating 0's

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