Section
Addresses
A
B
C
D
E
F
G
CE#
OE#
WE#
Data
VCC
20h
Data
In
A0h
Data
Out
VPP
Bus Cycle
Command
Function
A
Write
40h
Program
Setup
B
Write
Program
Address,
Program Data
Program
Command
Latch
Address and
Data
C
Time-out
N/A
Program
(10 µs)
D
Write
C0h
(Stops
Program)
Program
Verify
E
Time-out
N/A
F
Read
Compare
Data
11559G-9
G
Standby
N/A
Transition
(6 µs)
Program
Verification
Proceed per
Programming
Algorithm
Figure 4. AC Waveforms for Programming Operations
ANALYSIS OF PROGRAM TIMING
WAVEFORMS
Program Setup/Program
Two-cycle write commands are required for program
operations (section A and B). The first program com-
mand (40h) is a Setup command and does not affect
the array data (section A).The second program com-
mand latches address and data required for program-
ming on the falling and rising edge of WE# respectively
(section B). The rising edge of this WE# pulse (section
B) also initiates the programming pulse. The device is
programmed on a byte by byte basis either sequentially
or randomly.
The program pulse occurs in section C.
Time-Out
A software timing routine (10 µs duration) must be initi-
ated on the rising edge of the WE# pulse of section B.
Note: An integrated stop timer prevents any possibility
of overprogramming by limiting each time-out period of
10 µs.
Program-Verify
Upon completion of the program timing routine, the mi-
croprocessor must write the program-verify command
(C0h). This command terminates the programming op-
eration on the rising edge of the WE# pulse (section D).
The program-verify command also stages the device
for data verification (section F). Another software timing
routine (6 µs duration) must be executed to allow for
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