Device operation M27C4001
10/25
Figure 5. Programming Flowchart
2.7 Program Inhibit
Programming of multiple M27C4001s in parallel with different data is also easily
accomplished. Except for E
, all like inputs including G of the parallel M27C4001 may be
common. A TTL low level pulse applied to a M27C4001's E
input, with V
PP
at 12.75V, will
program that M27C4001. A high level E
input inhibits the other M27C4001s from being
programmed.
2.8 Program Verify
A verify (read) should be performed on the programmed bits to determine that they were
correctly programmed. The verify is accomplished with G
at V
IL
, E at V
IH
, V
PP
at 12.75V and
V
CC
at 6.25V.
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 M27C4001. To activate
the ES mode, the programming equipment must force 11.5V to 12.5V on address line A9 of
the M27C4001 with V
PP
= V
CC
= 5V. Two identifier bytes may then be sequenced from the
device outputs by toggling address line A0 from V
IL
to V
IH
. All other address lines must be
held at V
IL
during Electronic Signature mode. Byte 0 (A0 = V
IL
) represents the manufacturer
code and byte 1 (A0 = V
IH
) the device identifier code. For the STMicroelectronics
M27C4001, these two identifier bytes are given in Table 3 and can be read-out on outputs
Q7 to Q0.
AI00760B
n = 0
Last
Addr
VERIFY
E = 100µs Pulse
++n
= 25
++ Addr
V
CC
= 6.25V, V
PP
= 12.75V
FAIL
CHECK ALL BYTES
1st: V
CC
= 6V
2nd: V
CC
= 4.2V
YES
NO
YES
NO
YES
NO
Obsolete Product(s) - Obsolete Product(s)
