m28f410 STMicroelectronics, m28f410 Datasheet - Page 27

• Manufacturer Part Number: m28f410
• Description: 4 Megabit X8 Or X16, Block Erase Flash Memory
• Manufacturer: STMicroelectronics

Write. Write operations are used to give Instruction
Commands to the memory or to latch input data to
be programmed. A write operation is initiated when
Chip Enable E is Low and Write Enable W is Low
with Output Enable G High. Commands, Input Data
and Addresses are latched on the rising edge of W
or E. As for the Read operation, when BYTE is Low
a byte is input, DQ8-DQ14 are ’don’t care’ and A-1
is an additional address. When BYTE is High a
word is input.
Output Disable. The data outputs are high imped-
ance when the Output Enable G is High with Write
Enable W High.
Standby. The memory is in standby when the Chip
Enable E is High. The power consumption is re-
duced to the standby level and the outputs are high
impedance, independent of the Output Enable G
or Write Enable W inputs.
Power Down. The memory is in Power Down when
RP is low. The power consumption is reduced to
the Power Down level, and Outputs are in high
impedance, independant of the Chip Enable E,
Output Enable G or Write Enable W inputs.
Electronic Signature. Two codes identifying the
manufacturer and the device can be read from
the memories, the manufacturer code for SGS-
THOMSON is 20h, and the device codes are 0F2h
for the M28F410 (Top Boot Block) and 0FAh for the
M28F420 (Bottom Boot Block). These codes allow
programming equipment or applications to auto-
matically match their interfaceto the characteristics
of the particular manufacturer’s product.
The Electronic Signature is output by a Read Array
operation when the voltage applied to A9 is at V
the manufacturer code is output when the Address
input A0 is Low and the device code when this input
is High. Other Address inputs are ignored. The
codes are output on DQ0-DQ7. When the BYTE
signal is High the outputs DQ8-DQ15 output 00h,
when Low these outputs are high impedance and
Address input A-1 is ignored.
The Electronic Signature can also be read, without
raising A9 to V
instruction RSIG (see below).
Instructions and Commands
The memories include a Command Interface (C.I.)
which latches commands written to the memory.
ID
, after giving the memory the
ID
,
The P/E.C. automatically sets bits b3 to b7 and
clears bit b6 & b7. It cannot clear bits b3 to b5. The
register can be read by the Read Status Register
(RSR) instruction and cleared by the Clear Status
Register (CLRS) instruction. The meaning of the
bits b3 to b7 is shown in Table 7. Bits b0 to b2 are
reserved for future use (and should be masked out
during status checks).
Read (RD) instruction. The Read instruction con-
sists of one write operation giving the command
0FFh. Subsequent read operations will read the
addressed memory array content and output a byte
or word depending on the level of the BYTE input.
Read Status Register (RSR) instruction. The
Read Status Register instruction may be given at
any time, including while the Program/Erase Con-
troller is active. It consists of one write operation
giving the command 70h.SubsequentRead opera-
tions output the contents of the Status Register.
The contents of the status register are latched on
the falling edge of E or G signals, and can be read
until E or G returns to its initial high level. Either E
or G must be toggled to V
erase operation will automatically output the con-
tents of the Status Register.
Read Electronic Signature (RSIG) instruction.
This instruction uses 3 operations.It consists of one
write operation giving the command 90h followed
by two read operations to output the manufacturer
and device codes. The manufacturer code, 20h, is
output when the address line A0 is Low, and the
device code, 0F2h for the M28F410 or 0FAh for the
M28F420, when A0 is High.
Instructions are made up from one or more com-
mands to perform memory Read, Read Status
Register, Read Electronic Signature, Erase, Pro-
gram, Clear Status Register, Erase Suspend and
Erase Resume. These instructions require from 1
to 3 operations, the first of which is always a write
operation and is followed by either a further write
operation to confirm the first command or a read
operation(s) to output data.
A Status Register indicates the P/E.C. status
Ready or Busy, the suspend/in-progress status of
erase operations, the failure/success of erase and
program operations and the low/correct value of
the Program Supply voltage V
Additionally, any read attempt during program or
IH
to update the latch.
PP
.
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