S-93C76A Datasheet, PDF (9/33 Pages) Seiko Instruments Inc – CMOS SERIAL E2PROM

Rev.3.2_00
CMOS SERIAL E²PROM
S-93C76A
„ Operation
All instructions are executed by making CS “H” and then inputting DI at the rising edge of the SK pulse. An
instruction is input in the order of its start bit, instruction, address, and data. The start bit is recognized
when “H” of DI is input at the rising edge of SK after CS has been made “H”. As long as DI remains “L”,
therefore, the start bit is not recognized even if the SK pulse is input after CS has been made “H”. The SK
clock input while DI is “L” before the start bit is input is called a dummy clock. By inserting as many dummy
clocks as required before the start bit, the number of clocks the internal serial interface of the CPU can
send out and the number of clocks necessary for operation of the serial memory IC can be adjusted.
Inputting the instruction is complete when CS is made “L”. CS must be made “L” once during the period of
t_CDS in between instructions.
“L” of CS indicates a standby status. In this status, input of SK and DI is invalid, and no instruction is
accepted.
1. Reading (READ)
The READ instruction is used to read the data at a specified address. When this instruction is
executed, the address A₀ is input at the rising edge of SK and the DO pin, which has been in a high-
impedance (Hi-Z) state, outputs “L”. Subsequently, 16 bits of data are sequentially output at the rising
edge of SK.
If SK is output after the 16-bit data of the specified address has been output, the address is
automatically incremented, and the 16-bit data of the next address is then output. By inputting SK
sequentially with CS kept at “H”, the data of the entire memory space can be read. When the address
is incremented from the last address (A₈ … A₁ A₀ = 1 … 1 1), it returns to the first address (A₈ … A₁ A₀
= 0 … 0 0).
CS
SK
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 26 27 28 29 30 31 32 42 43 44 45 46 47 48
DI
1 1 0 X A₈ A₇ A₆ A₅ A₄ A₃ A₂ A₁ A₀
Hi-Z
DO
Hi-Z
0 D₁₅ D₁₄ D₁₃
D₂ D₁ D₀ D₁₅ D₁₄ D₁₃
D₂ D₁ D₀ D₁₅ D₁₄ D₁₃
A₈A₇A₆A₅A₄A₃A₂A₁A₀+1
Figure 6 Read Timing
A₈A₇A₆A₅A₄A₃A₂A₁A₀+2
Seiko Instruments Inc.
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