s-93a86a Seiko Instruments Inc., s-93a86a Datasheet - Page 14

• Manufacturer Part Number: s-93a86a
• Description: Cmos Serial E2prom
• Manufacturer: Seiko Instruments Inc.

14
CMOS SERIAL E
S-93A86A
Function to Protect Against Write due to Erroneous Instruction Recognition
The S-93A86A provides a built-in clock pulse monitoring circuit which is used to prevent an erroneous write
operation by canceling write instructions (WRITE, ERASE, WRAL, and ERAL) recognized erroneously due
to an erroneous clock count caused by the application of noise pulses or double counting of clocks.
Instructions are cancelled if a clock pulse whose count other than the one specified for each write instruction
(WRITE, ERASE, WRAL, or ERAL) is detected.
<Example> Erroneous Recognition of Program Disable Instruction (EWDS) as Erase Instruction
Input EWDS instruction
Erroneous recognition as
ERASE instruction due to
noise pulse
Example of S-93A86A
In products that do not incorporate a clock pulse monitoring circuit, FFFF is
mistakenly written to address 00h. However the S-93A86A detects the over count
and cancels the instruction without performing a write operation.
(ERASE)
Figure 11 Example of Clock Pulse Monitoring Circuit Operation
2
PROM
CS
SK
DI
1
1
1
1
1
0
0
2
Seiko Instruments Inc.
Noise pulse
0
0
3
0
0
4
0
0
0
5
0
0
6
0
0
7
0
0
8
0
0
9
0
0
10 11
0
0
0
0
12 13
0
0
Rev.2.1
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