s-93c46b Seiko Instruments Inc., s-93c46b Datasheet - Page 20

• Manufacturer Part Number: s-93c46b
• Description: Cmos Serial E2prom
• Manufacturer: Seiko Instruments Inc.

20
CMOS SERIAL E
S-93C46B/56B/66B
Write Disable Function when Power Supply Voltage is Low
The S-93C46B/56B/66B 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 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
1.75 V Typ.
2
PROM
Figure 20 Operation when Power Supply Voltage is Low
DET
Write instruction cancelled
Write disable state (EWDS) automatically set
Seiko Instruments Inc.
)
Hysteresis
About 0.3 V
Release voltage ( + V
2.05 V Typ.
DET
Rev.4.3
)
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