TMS28F210

65536 BY 16-BIT

FLASH MEMORY

SMJS210D – DECEMBER 1992 – REVISED AUGUST 1997

11

POST OFFICE BOX 1443

erase-verify command (continued)

To determine whether or not all the words have been erased, the TMS28F210 applies a margin voltage to each

word. If FFFFh is read from the word, all bits in the designated word have been erased. The erase-verify

operation continues until all of the words have been verified. If FFFFh is not read from a word, an additional erase

operation needs to be executed. Figure 2 shows the combination of commands and bus operations for

electrically erasing the TMS28F210.

reset command

To reset the TMS28F210 after a set-up-erase operation or a set-up-program operation without changing the

contents in memory, write 00FFh into the command register two consecutive times. After executing the reset

command, the device defaults to the read mode.

Fastwrite algorithm

The TMS28F210 is programmed using the Texas Instruments fastwrite algorithm previously shown in Figure

1. This algorithm programs in a nominal time of two seconds.

Fasterase algorithm

The TMS28F210 is erased using the Texas Instruments fasterase algorithm shown in Figure 2. The memory

array needs to be programmed completely (using the fastwrite algorithm) before erasure begins. Erasure

typically occurs in one second.

parallel erasure

To reduce total erase time, several devices can be erased in parallel. Since each flash memory can erase at

a different rate, every device must be verified separately after each erase pulse. After a given device has been

erased successfully, the erase command should not be issued to this device again. All devices that complete

erasure should be masked until the parallel erasure process is finished shown in Figure 3.

Examples of how to mask a device during parallel erase include driving the E pin high, writing the read command

(0000h) to the device when the others receive a set-up-erase or erase command, or disconnecting it from all

electrical signals with relays or other types of switches.