S93A46A Datasheet, PDF (18/41 Pages) Seiko Instruments Inc – 125C OPERATION 3-WIRE SERIAL

125°C OPERATION 3-WIRE SERIAL E²PROM FOR AUTOMOTIVE
S-93A46A/56A/66A
Rev.6.1_00
 Write Protect Function during the Low Power Supply Voltage
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, 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 18). 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, 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 18 Operation during Low Power Supply Voltage
18
Seiko Instruments Inc.