7/15
M27W202
Table 9. Programming Mode DC Characteristics
(1)
(T
A
= 25 °C; V
CC
= 6.25V ± 0.25V; V
PP
= 12.75V ± 0.25V)
Note: 1. V
CC
must be applied simultaneously with or before V
PP
and removed simultaneously or after V
PP
.
Table 10. Programming Mode AC Characteristics
(1)
(T
A
= 25 °C; V
CC
= 6.25V ± 0.25V; V
PP
= 12.75V ± 0.25V)
Note: 1. V
CC
must be applied simultaneously with or before V
PP
and removed simultaneously or after V
PP
.
2. Sampled only, not 100% tested.
Symbol Parameter Test Condition Min Max Unit
I
LI
Input Leakage Current
0
V
IN
V
IH
±10 µA
I
CC
Supply Current 50 mA
I
PP
Program Current
E
= V
IL
50 mA
V
IL
Input Low Voltage –0.3 0.8 V
V
IH
Input High Voltage 2
V
CC
+ 0.5
V
V
OL
Output Low Voltage
I
OL
= 2.1mA
0.4 V
V
OH
Output High Voltage TTL
I
OH
= –400µA
2.4 V
V
ID
A9 Voltage 11.5 12.5 V
Symbol Alt Parameter Min Max Unit
t
AVPL
t
AS
Address Valid to Program Low 2 µs
t
QVPL
t
DS
Input Valid to Program Low 2 µs
t
VPHPL
t
VPS
V
PP
High to Program Low
s
t
VCHPL
t
VCS
V
CC
High to Program Low
s
t
ELPL
t
CES
Chip Enable Low to Program Low 2 µs
t
PLPH
t
PW
Program Pulse Width 95 105 µs
t
PHQX
t
DH
Program High to Input Transition 2 µs
t
QXGL
t
OES
Input Transition to Output Enable Low 2 µs
t
GLQV
t
OE
Output Enable Low to Output Valid 100 ns
t
GHQZ
(2)
t
DFP
Output Enable High to Output Hi-Z 0 130 ns
t
GHAX
t
AH
Output Enable High to Address Transition 0 ns
Programming
When delivered, all bits of the M27W202 are in the
1’ state. Data is introduced by selectively pro-
gramming ’0s into the desired bit locations. Al-
though only ’0’s will be programmed, both ’1’s and
0’s can be present in the data word. The
M27W202 is in the programming mode when V
PP
input is at 12.75V, E is at V
IL
and P is pulsed to V
IL
.
The data to be programmed is applied to 16 bits in
parallel, to the data output pins. The levels re-
quired for the address and data inputs are TTL.
V
CC
is specified to be 6.25V ± 0.25V.
M27W202
8/15
Figure 6. Programming and Verify Modes AC Waveforms
tAVPL
VALID
AI00706
A0-A15
Q0-Q15
V
PP
V
CC
P
G
DATA IN DATA OUT
E
tQVPL
tVPHPL
tVCHPL
tPHQX
tPLPH
tGLQV
tQXGL
tELPL
tGHQZ
tGHAX
PROGRAM VERIFY
Figure 7. Programming Flowchart
AI02734
n = 0
Last
Addr
VERIFY
P = 100µs Pulse
++n
= 25
++ Addr
V
CC
= 6.25V, V
PP
= 12.75V
FAIL
CHECK ALL WORDS
1st: V
CC
= 5V
2nd: V
CC
= 2.7V
YES
NO
YES
NO
YES
NO
PRESTO II Programming Algorithm
PRESTO II Programming Algorithm allows pro-
gramming of the whole array with a guaranteed
margin, in a typical time of 13 seconds. Program-
ming with PRESTO II consists of applying a se-
quence of 100 µs program pulses to each word
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 V
CC
much
higher than 3.6V, provides necessary margin to
each programmed cell.
Program Inhibit
Programming of multiple M27W202s in parallel
with different data is also easily accomplished. Ex-
cept for E
, all like inputs including G of the parallel
M27W202 may be common. A TTL low level pulse
applied to a M27W202's P
input, with E low and
V
PP
at 12.75V, will program that M27W202. A high
level E
input inhibits the other M27W202s from be-
ing 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 E
and G at V
IL
, P at V
IH
, V
PP
at 12.75V and V
CC
at
6.25V.
9/15
M27W202
On-Board Programming
The M27W202 can be directly programmed in the
application circuit. See the relevant Application
Note AN620.
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 ± 5°C am-
bient temperature range that is required when pro-
gramming the M27W202. To activate the ES
mode, the programming equipment must force
11.5V to 12.5V on address line A9 of the
M27W202 with V
PP
= V
CC
= 5V. Two identifier
bytes may then be sequenced from the device out-
puts by toggling address line A0 from V
IL
to V
IH
. All
other address lines must be held at V
IL
during
Electronic Signature mode. Byte 0 (A0 = V
IL
) rep-
resents the manufacturer code and byte 1
(A0 = V
IH
) the device identifier code. For the
STMicroelectronics M27W202, these two identifier
bytes are given in Table 4 and can be read-out on
outputs Q7 to Q0.
ERASURE OPERATION (applies to UV EPROM)
The erasure characteristics of the M27W201 are
such that erasure begins when the cells are ex-
posed to light with wavelengths shorter than ap-
proximately 4000 Å. It should be noted that
sunlight and some type of fluorescent lamps have
wavelengths in the 3000-4000 Å range. Data
shows that constant exposure to room level fluo-
rescent lighting could erase a typical M27W201 in
about 3 years, while it would take approximately 1
week to cause erasure when exposed to direct
sunlight. If the M27W201 is to be exposed to these
types of lighting conditions for extended periods of
time, it is suggested that opaque labels be put over
the M27W201 window to prevent unintentional
erasure. The recommended erasure procedure for
the M27W201 is exposure to short wave ultraviolet
light which has wavelength of 2537 Å. The inte-
grated dose (i.e. UV intensity x exposure time) for
erasure should be a minimum of 15 W-sec/cm
2
.
The erasure time with this dosage is approximate-
ly 15 to 20 minutes using an ultraviolet lamp with
12000 µW/cm
2
power rating. The M27W201
should be placed within 2.5 cm (1 inch) of the lamp
tubes during the erasure. Some lamps have a filter
on their tubes which should be removed before
erasure.

M27W202-100K6

Mfr. #:
Manufacturer:
STMicroelectronics
Description:
EPROM LOW VOLTAGE OTP
Lifecycle:
New from this manufacturer.
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