TMS29LF040, TMS29VF040

524288 BY 8BIT

FLASH MEMORIES

SMJS825D − SEPTEMBER 1995 − REVISED JUNE 1998

7

POST OFFICE BOX 1443

command definitions (continued)

COMMAND

BUS

CYCLES

1ST CYCLE

ADDR DATA

2ND CYCLE

ADDR DATA

3RD CYCLE

ADDR DATA

4TH CYCLE

ADDR DATA

5TH CYCLE

ADDR DATA

6TH CYCLE

ADDR DATA

Read‡

1

RA

RD

Reset/Read§

2

XXXXh F0h

RA

RD

Reset/Read§

4

5555h AAh

2AAAh 55h

5555h F0h

RA

RD

Algorithm selection

4

5555h AAh

2AAAh 55h

5555h 90h

RA

RD

Byte program

4

5555h AAh

2AAAh 55h

5555h A0h

PA

PD

Chip erase

6

5555h AAh

2AAAh 55h

5555h 80h

5555h AAh

2AAAh 55h

5555h 10h

Sector erase

6

5555h AAh

2AAAh 55h

5555h 80h

5555h AAh

2AAAh 55h

SA 30h

Sector-erase suspend

XXXXh B0h

Erase-suspend valid during sector-erase operation

Sector-erase resume

XXXXh 30h

Erase-resume valid only after erase-suspend

RA = Address of the location to be read

PA

= Address of the location to be programmed

SA = Address of the sector to be erased

Addresses A16, A17, and A18 select one of eight sectors

RD = Data to be read at selected address location

PD = Data to be programmed at selected address location

† Address pins A15, A16, A17, A18 = VIL or VIH for all bus cycle addresses except for program address (PA), sector address (SA), and read address

(RA).

‡ No command cycles are required when the device is in read mode.

§ The reset command is required to return to the read mode when the device is in the algorithm-selection mode or if DQ5 goes high.

reset/read command

The read mode is activated by writing either of the two reset command sequences into the command register.

The device remains in this mode until another valid command sequence is input into the command register.

Memory data is available in the read mode and can be read with standard microprocessor read-cycle timing.

On power up, the device defaults to the read mode; therefore, a reset command sequence is not required and

memory data is available.

algorithm-selection command

The algorithm-selection command allows access to a binary code that matches the device with the proper

programming and erase-command operations. After writing the three-bus-cycle command sequence, the first

byte of the algorithm-selection code (97h) can be read from address XX00h. The second byte of the code (94h)

can be read from address XX01h (see Table 2). This mode remains in effect until another valid command

sequence is written to the device.

Sector-protection can be determined using the algorithm-selection command. After issuing the three-bus-cycle

The sector address pins A16, A17, and A18 select the sector to be checked. The remaining address pins can

outputs a 0. This mode remains in effect until another valid command sequence is written to the device.

byte-program command

Byte-programming is a four-bus-cycle command sequence. The first three bus cycles put the device into the

program-setup state. The fourth bus cycle loads the address location and the data to be programmed into the

device. The addresses are latched on the falling edge of W and the data is latched on the rising edge of W inthe

fourth bus cycle. The rising edge of W starts the byte-program operation. The embedded byte-programming

function automatically provides voltage and timing to program and to verify the cell margin. Any further

commands written to the device during the program operation are ignored.