M27C256B-45XB7X View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M27C256B-45XB7X

256 Kbit (32Kb x 8) UV EPROM and OTP EPROM

STMicroelectronics 

M27C256B

Table 8B. Read Mode AC Characteristics (1)

(TA = 0 to 70°C, –40 to 85°C, –40 to 105°C or –40 to 125°C; VCC = 5V ± 5% or 5V ± 10%; VPP = VCC)

Symbol Alt

Parameter

Test Condition

-90

M27C256B

-10

-12

-15/-20/-25 Unit

Min Max Min Max Min Max Min Max

tAVQV

tACC

Address Valid to

Output Valid

E = VIL, G = VIL

90

100

120

150 ns

tELQV

tCE

Chip Enable Low to

Output Valid

G = VIL

90

100

120

150 ns

tGLQV

tOE

Output Enable Low to

Output Valid

E = VIL

40

50

60

65 ns

tEHQZ (2)

tDF

Chip Enable High to

Output Hi-Z

G = VIL

0 30 0 30 0 40 0 50 ns

tGHQZ (2)

tDF

Output Enable High

to Output Hi-Z

E = VIL

0 30 0 30 0 40 0 50 ns

tAXQX

tOH

Address Transition to

Output Transition

E = VIL, G = VIL

0

0

0

Notes: 1. VCC must be applied simultaneously with or before VPP and removed simultaneously or after VPP.

2. Sampled only, not 100% tested.

0

ns

Figure 5. Read Mode AC Waveforms

A0-A14

E

G

Q0-Q7

VALID

tAVQV

tGLQV

tELQV

tAXQX

VALID

tEHQZ

tGHQZ

Hi-Z

AI00758B

Programming

When delivered (and after each erasure for UV

EPROM), all bits of the M27C256B are in the ”1”

state. Data is introduced by selectively program-

ming ”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

changea ’0’ to a ’1’ is by die expositionto ultraviolet

light (UV EPROM). The M27C256B is in the pro-

gramming 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 ad-

dress and data inputs are TTL. VCC is specified to

be 6.25 V ± 0.25 V.

6/15

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