M27W256 Ver la hoja de datos (PDF) - STMicroelectronics
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M27W256 Datasheet PDF : 15 Pages
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M27W256
Table 9. Programming Mode DC Characteristics (1)
(TA = 25 °C; VCC = 6.25V ± 0.25V; VPP = 12.75V ± 0.25V)
Symbol
Parameter
Test Condition
Min
ILI
Input Leakage Current
VIL ≤ VIN ≤ VIH
ICC
Supply Current
IPP
Program Current
E = VIL
VIL
Input Low Voltage
VIH
Input High Voltage
–0.3
2
VOL
Output Low Voltage
VOH
Output High Voltage TTL
IOL = 2.1mA
IOH = –1mA
3.6
VID
A9 Voltage
11.5
Note: VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP.
Table 10. Programming Mode AC Characteristics (1)
(TA = 25 °C; VCC = 6.25V ± 0.25V; VPP = 12.75V ± 0.25V
Symbol
Alt
Parameter
Min
tAVEL
tAS Address Valid to Chip Enable Low
2
tQVEL
tDS Input Valid to Chip Enable Low
2
tVPHEL
tVPS VPP High to Chip Enable Low
2
tVCHEL
tVCS VCC High to Chip Enable Low
2
tELEH
tPW Chip Enable Program Pulse Width
95
tEHQX
tDH Chip Enable High to Input Transition
2
tQXGL
tOES Input Transition to Output Enable Low
2
tGLQV
tOE Output Enable Low to Output Valid
tGHQZ
tDFP Output Enable High to Output Hi-Z
0
tGHAX
tAH Output Enable High to Address Transition
0
Note: VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP.
Max
± 10
50
50
0.8
VCC + 0.5
0.4
12.5
Max
105
100
130
Unit
µA
mA
mA
V
V
V
V
V
Unit
µs
µs
µs
µs
µs
µs
µs
ns
ns
ns
Programming
The M27W256 has been designed to be fully com-
patible with the M27C256B and has the same
electronic signature. As a result the M27W256 can
be programmed as the M27C256B on the same
programming equipments applying 12.75V on VPP
and 6.25V on VCC by the use of the same PRES-
TO II algorithm. When delivered (and after each
erasure for UV EPROM), all bits of the M27W256
are in the ’1’ state. Data is introduced by selective-
ly programming ’0’s into the desired bit locations.
Although only ’0’s will be programmed, both ’1’s
and ’0’s can be present in the data word. The only
way to change a ’0’ to a ’1’ is by die exposure to ul-
traviolet light (UV EPROM). The M27W256 is in
the programming mode when VPP input is at
12.75V, G is at VIH and E is pulsed to VIL. The data
to be programmed is applied to 8 bits in parallel to
the data output pins. The levels required for the
address and data inputs are TTL. VCC is specified
to be 6.25 V ± 0.25 V.
7/15
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