S-34C02A Datasheet, PDF (23/34 Pages) Seiko Instruments Inc – 2-WIRE CMOS SERIAL E2PROM FOR DIMM SERIAL PRESENCE DETECT

2-WIRE CMOS SERIAL E2PROM FOR DIMM SERIAL PRESENCE DETECT
Rev.1.2_00
S-34C02A
3. Phase adjustment during S-34C02A access
The S-34C02A does not have a pin to reset (the internal circuit). The users cannot forcibly reset it externally. If the
communication to the S-34C02A interrupted, the users need to handle it as you do for software.
Although the reset signal is input to the master device, the S-34C02A’s internal circuit does not go in reset, but it does
by inputting a stop condition to the S-34C02A. The S-34C02A keeps the same status thus cannot do the next
operation. Especially, this case is correspond 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) the S-34C02A. How to reset is shown below.
[How to reset S-34C02A]
The S-34C02A is able to be reset by a start and stop instructions. When the S-34C02A 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 instruction. Figure 23 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, the S-34C02A interrupts the acknowledgment output operation or data
output, so input a start condition^*1. When a start condition is input, the S-34C02A is reset. To make doubly sure,
input the stop condition to the S-34C02A. The normal operation is then possible.
Start
Condition
SCL
SDA
Dummy Clock
1
2
8
9
Start
Condition
Stop
Condition
Figure 23 Resetting S-34C02A
*1. After 9 clocks (dummy clock), if the SCL clock contuniues to being output without inputting a start condition, S-
34C02A may go in the Write operation when it receives a stop condition. To prevent this, input a start condition
after 9 clock (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.
Seiko Instruments Inc.
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