M39432

18/28

Figure 13. Write Mode AC Waveforms (W controlled)

2. Addresses are latched on the falling edge of W, Data are latched on the rising edge of W.

AI01953

E

(1)

G

W

A0-A18

DQ0-DQ7

VALID

VALID

VCC

tVCHEL

tWHEH

tWHWL

tELWL

tAVWL

tWHGL

tWLAX

tWHDX

WRITE CYCLE

tDVWH

tWLWH

tGHWL

RB

tWHRL

tWHRH

The Toggle bit (DQ6) stops toggling when the

Erase cycle is suspended. The Toggle bit status

must be monitored using an address that is not in

the Flash sector being erased. DQ6 will stop

toggling within 15

µs of the Erase Suspend

instruction having been sent. The M39432 will

then be set automatically into Read Flash Memory

mode.

When an Erase cycle is suspended, reading from

the Flash sectors that were being erased will

return invalid data. Reading is valid from any Flash

sectors that are not being erased. During an Erase

Suspend cycle, the Flash memory responds only

to Erase Resume and Reset instructions.

A Reset instruction will definitively abort the erase

cycle, and can leave invalid data in the Flash

sectors that was being erased.

Erase Resume Instruction. If an Erase Suspend

instruction was the last to have been executed,

this instruction allows the Erase cycle to be

resumed. The Erase Resume instruction involves

writing 30h to any address (as shown in Table 4).

Flash Sector Protection and Unprotection

Each Flash sector can be individually protected

against Program or Erase instructions. This mode

(specified in Table 11) and the Flash sector

address is applied on A16, A17 and A18, as

shown in Figure 8 and Table 9.

Flash Sector Protection is programmed with the

help of a specific sequence of levels applied on the

EF, EE, G, A0, A1, A6, A9, A16, A17 and A18

lines, as shown in Table 9.

Any attempt to Program or Erase a protected

Flash sector is ignored by the device.

Flash sectors can be unprotected, to allow the

subsequent updating of their contents. The Sector

Unprotection operation unprotects all sectors

together (from sector 0 up to sector 7).

The Flash Sector Unprotection operation is

invoked by applying the specific levels on the EF,

EE, G, A0, A1, A6, A9, A12, A16, A17 and A18

lines, as shown in Table 10.

Verification of the protection status can be

obtained

after

each

new

sector

has

been

protected,

or

after

all

sectors

have

been