S-24C02DI-J8T1U5 Datasheet, PDF (22/47 Pages) Seiko Instruments Inc – Write protect function during low power supply voltage

2-WIRE SERIAL E²PROM
S-24C02D/04D/08D16D
Rev.3.0_01_U
3. Phase adjustment of the I²C-bus product
The I²C-bus product does not have a pin to reset (the internal circuit). The users cannot forcibly reset it externally. If
the communication interrupted, the users need to handle it as you do for software.
In this IC, users are able to reset the internal circuit by inputting a start condition and a stop condition.
Although the reset signal is input to the master device, this IC’s internal circuit does not go in reset, but it does by
inputting a stop condition to this IC. This IC keeps the same status thus cannot do the next operation. Especially, this
case corresponds to that only the master device is reset when the power supply voltage drops.
If the power supply voltage restored in this status, input the instruction after resetting (adjusting the phase with the
master device) this IC. How to reset is shown below.
[How to reset this IC]
This IC is able to be reset by a start and stop instructions. When this IC is reading data "0" or is outputting the
acknowledgment signal, outputs "0" to the SDA line. In this status, the master device cannot output an instruction to
the SDA line. In this case, terminate the acknowledgment output operation or the Read operation, and then input a
start condition.
Figure 20 shows this procedure.
First, input a start condition. Then transmit 9 clocks (dummy clock) of SCL. During this time, the master device sets
the SDA line to "H". By this operation, this IC interrupts the acknowledgment output operation or data output, so
input a start condition^*1. When a start condition is input, this IC is reset. To make doubly sure, input the stop
condition to this IC. The normal operation is then possible.
Start
Condition
Dummy Clock
Start
Condition
Stop
Condition
SCL
1
2
8
9
SDA
Figure 20 Resetting Method
*1. After 9 clocks (dummy clock), if the SCL clock continues to being output without inputting a start condition, this
IC may go in the write operation when it receives a stop condition. To prevent this, input a start condition after 9
clocks (dummy clock).
Remark Regarding this reset procedure with dummy clock, it is recommended to perform at the system
initialization after applying the power supply voltage.
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