LS80C52 datasheet(20/23 Pages) INTEL

20 / 23 page

8XC525458

272336 – 21

See Table 4 for proper input on these pins

Figure 10 Programming the EPROM

PROGRAMMING ALGORITHM

Refer to Table 4 and Figures 10 and 11 for address

data and control signals set up To program the

87C5X the following sequence must be exercised

1 Input the valid address on the address lines

2 Input the appropriate data byte on the data

lines

3 Activate the correct combination of control sig-

nals

4 Raise EA VPP from VCC to 1275V g025V

5 Pulse ALEPROG 5 times for the EPROM ar-

ray and 25 times for the encryption table and

the lock bits

Repeat 1 through 5 changing the address and data

for the entire array or until the end of the object file is

reached

PROGRAM VERIFY

Program verify may be done after each byte or block

of bytes is programmed In either case a complete

verify of the programmed array will ensure reliable

programming of the 87C5X

The lock bits cannot be directly verified Verification

of the lock bits is done by observing that their fea-

tures are enabled

272336 – 22

Figure 11 Programming Signal’s Waveforms

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