S-93C76A Datasheet, PDF (10/33 Pages) Seiko Instruments Inc – CMOS SERIAL E2PROM

CMOS SERIAL E²PROM
S-93C76A
Rev.3.2_00
2. Writing (WRITE, ERASE, WRAL, ERAL)
Write instructions (WRITE, ERASE, WRAL, and ERAL) are used to start writing data to the non-volatile
memory by making CS “L” after the specified number of clocks has been input.
The write operation is completed within the write time t_PR (10 ms) no matter which write instruction is
used. The typical write time is less than half 10 ms. If the end of the write operation is known,
therefore, the write cycle can be minimized. To ascertain the end of a write operation, make CS “L” to
start the write operation and then make CS “H” again to check the status of the DO output pin. This
series of operations is called a verify operation.
If DO outputs “L” during the verify operation period in which CS is “H”, it indicates that a write operation
is in progress. If DO outputs “H”, it indicates that the write operation is finished. The verify operation
can be executed as many times as required. This operation can be executed in two ways. One is
detecting the positive transition of DO output from “L” to “H” while holding CS at “H”. The other is
detecting the positive transition of DO output from “L” to “H” by making CS “H” once and checking DO
output, and then returning CS to “L”.
During the write period, SK and DI are invalid. Do not input any instructions during this period. Input an
instruction while the DO pin is outputting “H” or is in a high-impedance state. Even while the DO pin is
outputing “H”, DO immediately goes into a high-impedance (Hi-Z) state if “H” of DI (start bit) is input at
the rising edge of SK.
Keep DI “L” during the verify operation period.
2. 1 Writing data (WRITE)
This instruction is used to write 16-bit data to a specified address.
After making CS “H”, input a start bit, the WRITE instruction, an address, and 16-bit data. If data of
more than 16 bits is input, the written data is sequentially shifted at each clock, and the 16 bits input
last are the valid data. The write operation is started when CS is made “L”. It is not necessary to
set data to “1” before it is written.
tCDS
CS
Verify
Stand by
SK
1 2 3 4 5 6 7 8 9 10 11 12 13 14
29
DI
<1> 0 1 X A8 A7 A6 A5 A4 A3 A2 A1 A0 D15
D0
DO
Hi-Z
tSV
tHZ1
Busy Ready _Hi-Z
tPR
Figure 7 Data Write Timing
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