tAVPL

VALID

AI00779

A0-A12

Q0-Q7

VPP

VCC

P

G

DATA IN

DATA OUT

E

tQVPL

tVPHPL

tVCHPL

tPHQX

tPLPH

tGLQV

tQXGL

tELPL

tGHQZ

tGHAX

PROGRAM

VERIFY

Figure 6. Programming and Verify Modes AC Waveforms

AI01167

n= 1

Last

Addr

VERIFY

P = 1ms Pulse

++n

>25

++ Addr

VCC = 6V, VPP = 12.5V

FAIL

CHECK ALL BYTES

1st: VCC =6V

2nd: VCC = 4.2V

YES

NO

YES

NO

YES

NO

P = 3ms Pulse by n

Figure 7. Programming Flowchart

Programming

When delivered (and after each erasure for UV

EPROM), all bits of the M27C64A are in the “1”

state. Data is introduced by selectively program-

ming ”0s” into the desired bit locations. Although

only “0s” will be programmed, both “1s” and “0s”

can be present in the data word. The only way to

change a “0” to a ”1” is by die exposition to ultra-

violet light (UV EPROM). The M27C64A is in the

E and P are at TTL-low. The data to be programmed

is applied 8 bits in parallel to the data output pins.

The levels required for the address and data inputs

± 0.25V.

High Speed Programming

The high speed programming algorithm, described

in the flowchart, rapidly programs the M27C64A

using an efficient and reliable method, particularly

suited to the production programming environ-

ment. An individual device will take around1 minute

to program.

Program Inhibit

Programming of multiple M27C64A in parallel with

different data is also easily accomplished. Except

for E, all like inputs including G of the parallel

M27C64A may be common. A TTL low level pulse

7/11

M27C64A