M39432 Datasheet, PDF (18/28 Pages) STMicroelectronics – Single Chip 4 Mbit Flash Memory and 256 Kbit Parallel EEPROM

M39432
Figure 13. Write Mode AC Waveforms (W controlled)
WRITE CYCLE
A0-A18
VALID
E ⁽¹⁾
tAVWL
tELWL
G
tGHWL
tWLWH
W
tWLAX
DQ0-DQ7
tDVWH
VALID
RB
VCC
tVCHEL
tWHEH
tWHGL
tWHWL
tWHDX
tWHRH
tWHRL
Note: 1. E signifies EF when EE = VIH, and it signifies EE when EF = VIH.
2. Addresses are latched on the falling edge of W, Data are latched on the rising edge of W.
AI01953
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
is activated when both A9 and G are set to V_ID
(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
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