M27C405-100B6TR STMICROELECTRONICS [STMicroelectronics], M27C405-100B6TR Datasheet - Page 9

• Manufacturer Part Number: M27C405-100B6TR
• Description: 4 Mbit 512Kb x 8 OTP EPROM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Figure 7. Programming Flowchart
PRESTO II Programming Algorithm
PRESTO II Programming Algorithm allows the
whole array to be programmed with a guaranteed
margin, in a typical time of 52.5 seconds.Program-
ming with PRESTO II consists of applying a se-
quence of 100 s program pulses to each byte until
a correct verify occurs (see Figure 7). During pro-
gramming and verify operation, a MARGIN MODE
circuit is automaticallyactivated in order to guaran-
tee that each cell is programmed with enough
margin. No overprogram pulse is applied since the
verify in MARGIN MODE provides the necessary
margin to each programmed cell.
Program Inhibit
Programming of multiple M27C405s in parallelwith
different data is also easily accomplished. Except
for E, all like inputs including G of the parallel
M27C405 may be common. A TTL low level pulse
appliedto a M27C405’sE input,with V
will program that M27C405. A high level E input
inhibits the other M27C405s from being pro-
grammed.
YES
NO
FAIL
= 25
++n
V CC = 6.25V, V PP = 12.75V
CHECK ALL BYTES
NO
2nd: V CC = 4.2V
E = 100 s Pulse
1st: V CC = 6V
VERIFY
n = 0
Addr
Last
YES
YES
NO
++ Addr
PP
AI00760B
at 12.75V,
Figure 8. On-Board Programming Flowchart
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 G at
V
On-Board Programming
Programming the M27C405 may be performed
directly in the application circuit, however this re-
quires modification to the PRESTO II Algorithm
(see Figure 8). For in-circuit programming V
determined by the user and normally is compatible
with other componentsusing the same supply volt-
age. It is recommended that the maximum value of
V
used.
Typically V
ing V
does not affect the programming, it gives a higher
test capability in VERIFY mode.
V
enable the programming.
IL
CC
PP
, E at V
must be kept at 12.75 volts to maintain and
which remains compatible with the circuit is
CC
YES
NO
=5V is recommended. The value of V
FAIL
= 25
++n
IH
CC
, V
=5.5V for programming systems us-
PP
SET MARGIN MODE
CHECK ALL BYTES
NO
at 12.75V and V
E = 10 s Pulse
E = 10 s Pulse
V PP = 12.75V
V PP = V CC
VERIFY
n = 0
Addr
Last
?
YES
YES
NO
++ Addr
CC
at 6.25V.
AI01349
M27C405
CC
9/15
CC
is