M27C64 STMICROELECTRONICS [STMicroelectronics], M27C64 Datasheet - Page 4

• Manufacturer Part Number: M27C64
• Description: 64 Kbit 8Kb x 8 UV EPROM and OTP EPROM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M27C64A
Programming
When delivered (and after each erasure for UV
EPROM), all bits of the M27C64A are in the "1"
state. Data is introduced by selectively program-
ming "0"s into the desired bit locations. Although
only "0"s will be programmed, both "1"s and "0"s
can be present in the data word. The only way to
change a "0" to a "1" is by die exposition to ultra-
violet light (UV EPROM). The M27C64A is in the
programming mode when V
is at V
programmed is applied to 8 bits in parallel to the
data output pins. The levels required for the ad-
dress and data inputs are TTL. V
be 6V
High Speed Programming
The high speed programming algorithm, described
in the flowchart, rapidly programs the M27C64A
using an efficient and reliable method, particularly
suited to the production programming environ-
ment. An individual device will take around 1 minute
to program.
Program Inhibit
Programming of multiple M27C64A in parallel with
different data is also easily accomplished. Except
for E, all like inputs including G of the parallel
M27C64A may be common. A TTL low level pulse
applied to a M27C64A P input, with E low and V
at 12.5V, will program that M27C64A. A high level
4/12
IL
0.25V.
and P is pulsed to V
pp
input is at 12.5V, E
IL
. The data to be
CC
is specified to
PP
E input inhibits the other M27C64A from being
programmed.
Program Verify
A verify (read) should be performed on the pro-
grammed bits to determine that they were correctly
programmed. The verify is accomplished with E
and G at V
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
temperature range that is required when program-
ming the M27C64A. To activate the ES mode, the
programming equipment must force 11.5V to 12.5V
on address line A9 of the M27C64A, with
V
sequenced from the device outputs by toggling
address line A0 from V
lines must be held at V
ture mode.
Byte 0 (A0=V
and byte 1 (A0=V
the STMicroelectronics M27C64A, these two iden-
tifier bytes are given in Table 4 and can be read-out
on outputs Q0 to Q7.
PP
=V
CC
=5V. Two identifier bytes may then be
IL
, P at V
IL
) represents the manufacturer code
IH
) the device identifier code. For
IH
, V
IL
IL
PP
to V
during Electronic Signa-
at 12.5V and V
IH
. All other address
5 C ambient
CC
at 6V.