EN27C512 Datasheet, PDF (3/12 Pages) List of Unclassifed Manufacturers – 512KBIT EPROM (64K x 8)

FIGURE 4. BLOCK DIAGRAM
EN27C512
FUNCTIONAL DESCRIPTION
THE QUIKRITE^TM PROGRAMMING OF THE EN27C512
When the EN27C512 is delivered, the chip has all 512K bits in the “ONE”, or
HIGH state. “ZEROs” are loaded into the EN27C512 through the procedure of programming.
The programming mode is entered when 12.75 ± 0.25V is applied to the OE /V_PP pin and
CE is at V_IL. For programming, the data to be programmed is applied with 8 bits in parallel to
the data pins.
The QUIKRITE^TM programming flowchart in Figure 5 shows Eon’s interactive programming
algorithm. The interactive algorithm reduces programming time by using 20 µs to 100 µs
programming pulses and giving each address only as many pulses as is necessary in order to
reliably program the data. After each pulse is applied to a given address, the data in that
address is verified. If the data is not verified, additional pulses are given until it is verified or
until the maximum number of pulses is reached. This process is repeated while sequencing
through each address of the EN27C512. This part of the programming algorithm is done at
VCC = 6.25V to assure that each EPROM bit is programmed to a sufficiently high threshold
voltage. This ensures that all bits have sufficient margin. After the final address is completed,
the entire EPROM memory is read at V_CC = 5.25 ± 0.25V to verify the entire memory.
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