M27V256

6/15

Figure 5. Read Mode AC Waveforms

AI00758B

tAXQX

tEHQZ

A0-A14

E

G

Q0-Q7

tAVQV

tGHQZ

tGLQV

tELQV

VALID

Hi-Z

VALID

2. Sampled only, not 100% tested.

Symbol

Alt

Parameter

Test Condition

M27V256

Unit

-120

-150

-200

Min

Max

Min

Max

Min

Max

120

150

200

ns

Chip Enable Low to Output

Valid

120

150

200

ns

Output Enable Low to Output

Valid

45

50

60

ns

(2)

Chip Enable High to Output

Hi-Z

035

0

40

050

ns

(2)

Output Enable High to Output

Hi-Z

035

0

40

050

ns

Address Transition to Output

Transition

E = VIL, G = VIL

0

0

0

ns

Programming

The M27V256 has been designed to be fully com-

patible with the M27C256B and has the same

electronic signature. As a result the M27V256 can

be programmed as the M27C256B on the same

TO II algorithm. When delivered (and after each

erasure for UV EPROM), all bits of the M27V256

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 exposition to

ultraviolet light (UV EPROM). The M27V256 is in

to be programmed is applied to 8 bits in parallel to

the data output pins. The levels required for the

to be 6.25 V

± 0.25 V.