S-93A46A Datasheet, PDF (17/34 Pages) Seiko Instruments Inc – CMOS SERIAL E2PROM

Rev.2.1_00
CMOS SERIAL E²PROM
S-93A46A/56A/66A
„ Write Disable Function when Power Supply Voltage is Low
The S-93A46A/56A/66A provides a built-in detector to detect a low power supply voltage and disable writing.
When the power supply voltage is low or at power application, the write instructions (WRITE, ERASE,
WRAL, and ERAL) are cancelled, and the write disable state (EWDS) is automatically set. The detection
voltage is 1.75 V typ., the release voltage is 2.05 V typ., and there is a hysteresis of about 0.3 V (Refer to
Figure 16). Therefore, when a write operation is performed after the power supply voltage has dropped and
then risen again up to the level at which writing is possible, a write enable instruction (EWEN) must be sent
before a write instruction (WRITE, ERASE, WRAL, or ERAL) is executed.
When the power supply voltage drops during a write operation, the data being written to an address at that
time is not guaranteed.
Power supply voltage
Detection voltage (−V_DET)
1.75 V Typ.
Hysteresis
About 0.3 V
Release voltage (+V_DET)
2.05 V Typ.
Write instruction cancelled
Write disable state (EWDS) automatically set
Figure 16 Operation when Power Supply Voltage is Low
Seiko Instruments Inc.
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