M27C256B-45F6 Ver la hoja de datos (PDF) - STMicroelectronics
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M27C256B-45F6 Datasheet PDF : 24 Pages
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Device operation
M27C256B
Figure 4.
Programming flowchart
VCC = 6.25V, VPP = 12.75V
n=0
E = 100µs Pulse
NO
++n
= 25
NO
VERIFY
++ Addr
YES
YES
Product(s) FAIL
Last NO
Addr
YES
CHECK ALL BYTES
1st: VCC = 6V
2nd: VCC = 4.2V
AI00760B
olete 2.7
Program inhibit
bs Programming of multiple M27C256Bs in parallel with different data is also easily
O accomplished. Except for E, all like inputs including G of the parallel M27C256B may be
- common. A TTL low level pulse applied to a M27C256B's E input, with VPP at 12.75V, will
) program that M27C256B. A high level E input inhibits the other M27C256Bs from being
t(s programmed.
roduc 2.8
Program Verify
P A verify (read) should be performed on the programmed bits to determine that they were
tecorrectly programmed. The verify is accomplished with G at VIL, E at VIH, VPP at 12.75V and
leVCC at 6.25V.
Obso 2.9
Electronic signature
The Electronic Signature (ES) mode allows the reading out of a binary code from an
EPROM that will identify its manufacturer and type. This mode is intended for use by
programming equipment to automatically match the device to be programmed with its
corresponding programming algorithm. The ES mode is functional in the 25°C ± 5°C
ambient temperature range that is required when programming the M27C256B. To activate
the ES mode, the programming equipment must force 11.5V to 12.5V on address line A9 of
the M27C256B, with VCC = VPP = 5V. Two identifier bytes may then be sequenced from the
device outputs by toggling address line A0 from VIL to VIH. All other address lines must be
held at VIL during Electronic Signature mode. Byte 0 (A0 = VIL) represents the manufacturer
code and byte 1 (A0 = VIH) the device identifier code. For the STMicroelectronics
M27C256B, these two identifier bytes are given in Table 3 and can be read-out on outputs
Q7 to Q0.
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