s-8426a Seiko Instruments Inc., s-8426a Datasheet - Page 10

• Manufacturer Part Number: s-8426a
• Description: Battery Backup Switching Ic
• Manufacturer: Seiko Instruments Inc.

10
BATTERY BACKUP SWITCHING IC
S-8426A Series
3. Switch Unit
2. 2 PREEND Voltage Detector
2. 3 RESET Voltage Detector
The switch unit consists of the V
transistor M1 (Refer to Figure 14).
The PREEND voltage detector monitors input voltage (V
selected in the range of 1.7 to 3.4 V in 0.1 V step. By using this function, IC notifies if the backup battery is
scarce. The result of detection is output at the PREEND pin: “Low” for lower voltages than the detection level
and “High” for higher voltages than the release level.
The RESET voltage detector monitors output voltage (V
be selected in the range of 1.7 to 3.4 V in 0.1 V step. The result of detection is output at the RESET pin:
“Low” for lower voltages than the detection level and “High” for higher voltages than the release level. RESET
outputs the normal logic if the VOUT pin voltage is 1.0 V or more.
Caution
The PREEND
Practically, the current is taken from the VBAT side, and consider the I/O voltage difference
(V
dif
) of M1 when M1 is ON.
VIN
and RESET
SW1
REG2
controller
Switch
and V
Seiko Instruments Inc.
SW2
VOUT
voltage detectors use the different pins, respectively.
detectors, a switch controller, voltage regulator 2, and switch
Figure 14
M1
detector
V
SW1
BAT
OUT
) (VBAT pin voltage). The detection voltage can be
) (VOUT pin voltage). The detection voltage can
detector
V
SW2
VBAT
Rev.1.0
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