M27W401-100B6TR STMicroelectronics, M27W401-100B6TR Datasheet - Page 8

• Manufacturer Part Number: M27W401-100B6TR
• Description: 4 Mbit 512Kb x 8 Low Voltage UV EPROM and OTP EPROM
• Manufacturer: STMicroelectronics

M27W401
Figure 6. Programming and Verify Modes AC Waveforms
Figure 7. Programming Flowchart
8/15
YES
NO
= 25
FAIL
++n
V CC
A0-A18
Q0-Q7
V PP
E
G
V CC = 6.25V, V PP = 12.75V
CHECK ALL BYTES
NO
2nd: V CC = 2.7V
E = 100 s Pulse
1st: V CC = 5V
VERIFY
n = 0
Addr
Last
YES
YES
tVPHEL
tVCHEL
NO
tQVEL
tAVPL
tELEH
++ Addr
DATA IN
PROGRAM
AI00760C
VALID
tEHQX
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. Pro-
gramming with PRESTO II consists of applying a
sequence of 100 s program pulses to each byte
until a correct verify occurs (see Figure 7). During
programming and verify operation, a MARGIN
MODE circuit is automatically activated in order to
guarantee that each cell is programmed with
enough margin. No overprogram pulse is applied
since the verify in MARGIN MODE at VCC much
higher than 3.6V, provides the necessary margin
to each programmed cell.
Program Inhibit
Programming of multiple M27W401s in parallel
with different data is also easily accomplished. Ex-
cept for E, all like inputs including G of the parallel
M27W401 may be common. A TTL low level pulse
applied to a M27W401’s E input, with V
12.75V, will program that M27W401. A high level
E input inhibits the other M27W401s 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
AI00725
CC
at 6.25V.
PP
at