pulse width between 45ms and 55ms. Multiple

pulses are not needed but will not cause device

damage. No pins should be left open. A high level

ming. M2716’s may be programmed in parallel in

this mode.

Program Verify Mode. The programming of the

M2716 may be verified either one byte at a time

during the programming (as shown in Figure 6) or

by reading all of the bytes out at the end of the

programming sequence. This can be done with

for all operating modes and can be maintained at

25V for all programming modes.

Program Inhibit Mode. The program inhibit mode

allows several M2716’s to be programmed simul-

taneously with different data for each one by con-

trolling which ones receive the program pulse. All

similar inputs of the M2716 may be paralleled.

gram a unit while inhibiting the program pulse to a

unit will keep it from being programmed and keep-

ERASURE OPERATION

The M2716 is erased by exposure to high intensity

ultraviolet light through the transparent window.

This exposure discharges the floating gate to its

initial state through induced photo current. It is

recommended that the M2716 be kept out of direct

sunlight. The UV content of sunlight may cause

a partial erasure of some bits in a relatively short

period of time.

An ultraviolet source of 2537 Å yielding a total

rating is used. The M2716 to be erased should be

placed 1 inch away from the lamp and no filters

should be used.

An erasure system should be calibrated peri-

odically. The erasure time is increased by the

square of the distance (if the distance is doubled

the erasure time goes up by a factor of 4). Lamps

lose intensity as they age, it is therefore important

to periodically check that the UV system is in good

order.

This will ensure that the EPROMs are being com-

pletely erased. Incomplete erasure will cause

symptoms that can be misleading. Programmers,

components, and system designs have been erro-

neously suspected when incomplete erasure was

the basic problem.

DEVICE OPERATION (cont’d)

Mode

EP

Q0 - Q7

Read

Data Out

Program

Data In

Verify

Data Out

Program Inhibit

Hi-Z

Deselect

X

Hi-Z

Standby

Hi-Z

Table 3. Operating Modes

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M2716