S-25C010A-H Datasheet, PDF (24/33 Pages) Seiko Instruments Inc – OPERATION SPI SERIAL E2PROM FOR AUTOMOTIVE

105°C OPERATION SPI SERIAL E²PROM FOR AUTOMOTIVE
S-25C010A/020A/040A H Series
Rev.2.3_01_C
 Write Protect Function during the Low Power Supply Voltage
The S-25C010A/020A/040A has a built-in detection circuit which operates with the low power supply voltage. The S-
25C010A/020A/040A cancels the Write operation (WRITE, WRSR) when the power supply voltage drops and power-
on, at the same time, goes in the Write protect status (WRDI) automatically to reset bit WEL. The detection voltage is
1.20 V typ., the release voltage is 1.35 V typ., and its hysteresis is approx. 0.15 V (Refer to Figure 22).
To operate Write, after the power supply voltage dropped once but rose to the voltage level which allows Write again,
be sure to set the Write Enable Latch bit (WEL) before operating Write (WRITE, WRSR).
In the Write operation, data in the address written during the low power supply voltage is not assured.
Power supply voltage
Detection voltage (VDET)
1.20 V Typ.
Hysteresis
approx. 0.15 V
Release voltage (VDET)
1.35 V Typ.
Cancel the Write instruction
Set in Write protect (WRDI) automatically
Figure 22 Operation during Low Power Supply Voltage
 I/O Pin
1. Connection of input pin
All input pins in S-25C010A/020A/040A have the CMOS structure. Do not set these pins in high impedance during
operation when you design. Especially, set the CS input in the non-select status “H” during power-on/off and standby.
The error Write does not occur as long as the CS pin is in the non-select status “H”. Set the CS pin to VCC via a
resistor (the pull-up resistor of 10 kΩ to 100 kΩ).
If the CS pin and the SCK pin change from “L” to “H” simultaneously, data may be input from the SI pin.
To prevent the error for sure, it is recommended to pull down the SCK pin to GND. In addition, it is recommended to
pull up the SI pin, the WP pin and the HOLD pin to VCC, or pull down these pins to GND, respectively. Connecting the
WP pin and the HOLD pin to VCC directly is also possible when these pins are not in use.
2. Equivalent circuit of input and output pin
Figures 23 and 24 show the equivalent circuits of input pins in S-25C010A/020A/040A. A pull-up and pull-down
elements are not included in each input pin, pay attention not to set it in the floating state when you design.
Figure 25 shows the equivalent circuit of the output pin. This pin has the tri-state output of “H” level/“L” level/high
impedance.
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