Aeroflex Circuit Technology

SCD1668 REV A 4/28/98

Plainview NY (516) 694-6700

6

set-up command and data write cycles. Addresses are

latched on the falling edge of CE or WE, whichever

occurs later, while the data is latched on the rising edge

of CE or WE whichever occurs first. The rising edge of

CE or WE begins programming. Upon executing the pro-

gram algorithm command sequence the system is not

required to provide further controls or timings.

The

device will automatically provide adequate internally

generated program pulses and verity the programmed

cell status.

The automatic programming operation is

written to this bit at which time the device returns to the

read mode and addresses are no longer latched. The

device requires a valid address be supplied by the Sys-

tem at this time. Data Polling must be performed at the

memory location which is being programmed.

Programming is allowed in any address sequence and

across sector boundaries.

Figure 3 illustrates the programming algorithm using typ-

ical command strings and bus operations.

CHIP ERASE

Chip erase is a six bus cycle operation. There are two

'unlock' write cycles. These are followed by writing the

'set-up' command. Two more 'unlock' write cycles are

then followed by the chip erase command.

Chip erase does not require the user to program the

device prior to erase. Upon executing the erase algo-

rithm (Figure 4) sequence the device automatically will

program and verify the entire memory for an all zero data

pattern prior to electrical erase.

The system is not

required to provide any controls or timings during these

operations.

The automatic erase begins on the rising edge of the last

WE pulse in the command sequence and terminates

when the data in D7 is "1" (see Write Operation Status

section - Table 4) at which time the device returns to read

the mode. See Figures 4 and 9.

SECTOR ERASE

Sector erase is a six bus cycle operation. There are two

"unlock" write cycles. These are followed by writing the

"setup" command. Two more "unlock" write cycles are

then followed by the sector erase command. The sector

address (any address location within the desired sector)

is latched on the falling edge of WE, while the command

(data) is latched on the rising edge of WE. A time-out of

100µs from the rising edge of the last sector erase com-

mand will initiate the sector erase command(s).

Multiple sectors may be erased concurrently by writing

the six bus cycle operations as described above. This

sequence is followed with writes of the sector erase com-

mand 30H to address in other sectors desired to be con-

currently erased.

A time-out of 100µs from the rising

edge of the WE pulse for the last sector erase command

will initiate the sector erase.

If another sector erase

command is written within the 100µs time-out window

the timer is reset. Any command other than sector erase

within the time-out window will reset the device to the

read mode, ignoring the previous command string.

Loading the sector erase buffer may be done in any

sequence and with any number of sectors (0 to 7).

Sector erase does not require the user to program the

device prior to erase.

The device automatically pro-

grams all memory locations in the sector(s) to be erased

prior to electrical erase. When erasing a sector or sec-

tors the remaining unselected sectors are not affected.

The system is not required to provide any controls or tim-

ings during these operations.

Data Protection

The ACT–F512K8 is designed to offer protection against

accidental erasure or programming caused by spurious

system level singles that may exist during power transi-

tions. During power up the device automatically resets

the internal state machine in the read mode. Also, with

Table 3 — Commands Definitions

Command

Sequence

Bus

Write

Cycles

First Bus Write

Cycle

Second Bus Write

Cycle

Third Bus Write

Cycle

Fourth Bus

Read/Write Cycle

Fifth Bus Write

Cycle

Sixth Bus Write

Cycle

Required

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Addr

Data

Read/Reset

1

XXXH

F0H

Read/Reset

4

5555H

AAH

2AAAH

55H

5555H

F0H

RA

RD

Autoselect

4

5555H

AAH

2AAAH

55H

5555H

90H

Byte Program

6

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 Erase can be suspended during sector erase with Address (Don’t care), Data (B0H)

Sector Erase Resume

Erase can be resumed after suspend with Address (Don’t care), Data (30H)

NOTES:

1. Address bit A15, A16, A17 and A18 = X = Don't Care. Write Sequences may be initiated with A15 in either state.

2. Address bit A15, A16, A17 and A18 = X = Don't Care for all address commands except for Program Address (PA) and Sector Address (SA).

3. RA = Address of the memory location to be read

PA = Address of the memory location to be programmed. Addresses are latched on the falling edge of the WE pulse.

SA = Address of the sector to be erased. The combination of A18, A17, A16 will uniquely select any sector.

4. RD = Data read from location RA during read Operation.

PD = Data to be programmed at location PA. Data is latched on the rising edge of WE.