M27512-20F6 STMICROELECTRONICS [STMicroelectronics], M27512-20F6 Datasheet - Page 8

• Manufacturer Part Number: M27512-20F6
• Description: NMOS 512K 64K x 8 UV EPROM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

DEVICE OPERATION (cont’d)
The Fast Programming Algorithm utilizes two differ-
ent pulse types : initial and overprogram. The du-
ration of the initial E pulse(s) is 1ms, which will then
be followed by a longer overprogram pulse of length
3ms by n (n is an iteration counter and is equal to
the number of the initial one millisecond pulses
applied to a particular M27512 location), before a
correct verify occurs. Up to 25 one-millisecond
pulses per byte are provided for before the over
program pulse is applied.
The entire sequence of program pulses is per-
formed at V
cations at V
Programming cycle has been completed, all bytes
should be compared to the original data with
V
PRESTO Programming Algorithm
PRESTO Programming Algorithm allows to pro-
gram the whole array with a guaranted margin, in
a typical time of less than 50 seconds (to be com-
pared with 283 seconds for the Fast algorithm).
This can be achieved with the STMicroelectronics
M27512 due to several design innovations de-
scribed in the next paragraph that improves pro-
gramming efficiency and brings adequate margin
M27512
Figure 8. Fast Programming Flowchart
8/11
CC
= 5V.
YES
NO
FAIL
> 25
++n
CC
CC
= 6V and GV
= 6V and GV
V CC = 6V, V PP = 12.5V
V CC = 5V, V PP = 5V
CHECK ALL BYTES
E = 3ms Pulse by n
NO
E = 1ms Pulse
VERIFY
n = 1
Addr
Last
YES
YES
PP
PP
NO
= V
= 12.5V (byte verifi-
IL
). When the Fast
++ Addr
AI00774B
for reliability. Before starting the programming the
internal MARGIN MODE circuit is set in order to
guarantee that each cell is programmed with
enough margin.
Then a sequence of 500 s program pulses are
applied to each byte until a correct verify occurs.
No overprogram pulses are applied since the verify
in MARGIN MODE provides the necessary margin
to each programmed cell.
Program Inhibit
Programming of multiple M27512s in parallel with
different data is also easily accomplished. Except
for E, all like inputs (including GV
M27512 may be common. A TTL low level pulse
applied to a M27512’s E input, with GV
will program that M27512. A high level E input
inhibits the other M27512s from being pro-
grammed.
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 GV
and E at V
falling edge of E.
Figure 9. PRESTO Programming Flowchart
YES
NO
FAIL
= 25
++n
IL
. Data should be verified t
V CC = 6.25V, V PP = 12.75V
RESET MARGIN MODE
SET MARGIN MODE
V CC = 5V, V PP = 5V
CHECK ALL BYTES
NO
E = 500 s Pulse
VERIFY
n = 0
Addr
Last
YES
YES
NO
PP
++ Addr
) of the parallel
AI00773B
pp
DV
at 12.5V,
after the
pp