S-93A46BD0A-J8T2U3 Datasheet, PDF (21/39 Pages) Seiko Instruments Inc – Function to protect against write due to erroneous instruction recognition

Rev.1.2_00
FOR AUTOMOTIVE 125°C OPERATION 3-WIRE SERIAL E²PROM
S-93A46B/56B/66B/76B/86B
 Write Protect Function during the Low Power Supply Voltage
This IC provides a built-in detection circuit to detect a low power supply voltage. When the power supply voltage is low or
at power-on, the write instructions (WRITE, ERASE, WRAL, and ERAL) are cancelled, and the write disable (EWDS)
status is automatically set. The detection voltage is 1.55 V typ., the release voltage is 1.85 V typ., and there is a
hysteresis of about 0.3 V (refer to Figure 20). 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)
1.55 V typ.
Hysteresis
about 0.3 V
Release voltage (+V_DET)
1.85 V typ.
Write instructions are cancelled
Write disable status (EWDS) is automatically set
Figure 20 Operation during the Low Power Supply Voltage
21