AUTOMOTIVE 87C54 87C54-20
PROGRAMMING ALGORITHM
Refer to Table 3 and Figures 11 and 14 for address
data and control signals set up To program the
87C54 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 12 75V g0 25V
5 Pulse ALE PROG 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 programmed array will ensure reliable pro-
gramming of the 87C54
The lock bits cannot be directly verified Verification
of the lock bits is done by observing that their fea-
tures are enabled Refer to the EPROM Program
Lock section in this data sheet
5 Pulses
Figure 14 Programming Signal’s Waveforms
270849 – 25
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