M27C256B-10B1X STMICROELECTRONICS [STMicroelectronics], M27C256B-10B1X Datasheet - Page 8

• Manufacturer Part Number: M27C256B-10B1X
• Description: 256 Kbit (32Kb x 8) UV EPROM and OTP EPROM
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

M27C256B
Figure 6. Programming and Verify Modes AC Waveforms
Figure 7. Programming Flowchart
8/16
YES
NO
FAIL
= 25
++n
V CC
A0-A14
Q0-Q7
V PP
E
G
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
tVPHEL
tVCHEL
NO
tAVEL
tQVEL
tELEH
DATA IN
++ Addr
PROGRAM
AI00760B
VALID
tEHQX
PRESTO II Programming Algorithm
PRESTO II Programming Algorithm allows to pro-
gram the whole array with a guaranteed margin, in
a typical time of 3.5 seconds. Programming with
PRESTO II involves the application of a sequence
of 100µs program pulses to each byte until a cor-
rect verify occurs (see Figure 7). During program-
ming and verify operation, a MARGIN MODE
circuit is automatically activated in order to guar-
antee that each cell is programmed with enough
margin. No overprogram pulse is applied since the
verify in MARGIN MODE provides necessary mar-
gin to each programmed cell.
Program Inhibit
Programming of multiple M27C256Bs in parallel
with different data is also easily accomplished. Ex-
cept 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 V
at 12.75V, will program that M27C256B. A high
level E input inhibits the other M27C256Bs from
being programmed.
Program Verify
A verify (read) should be performed on the pro-
grammed bits to determine that they were correct-
ly programmed. The verify is accomplished with G
at V
tQXGL
IL
, E at V
VERIFY
tGLQV
DATA OUT
IH
, V
PP
at 12.75V and V
tGHQZ
tGHAX
AI00759
CC
at 6.25V.
PP